Phyto climatic gradient of vegetation and habitat specificity in the high ele...Shujaul Mulk Khan
Phyto-climatic gradient and ecological indicators can be used to understand the requirements, long term management and conservation strategies of natural habitats and species. For this purpose phytosociological attributes were measured using quadrats along transects on different slope aspects across an elevation range of 2450-4400 m. The 198 recorded plant species were placed in five Raunkiaer life form classes among which the Hemicryptophytes (51%) dominate the flora of the study area followed by Phanerophytes and Cryptophytes (Geophytes) with 15 and 13% dominance respectively. Therophytes and Chamaephytes are represented by smaller numbers (12 & 10% each). The phyto-climatic gradient of the vegetation was evaluated using Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA). Phyto-climatic relationships show that Phanerophytes especially tree species are widely distributed on northern aspect slopes whilst shrubs are more dominant on southern aspect slopes. Woody plants are dominant at lower altitudes (2450-2800 m), with a much smaller proportion occurring at middle elevations (2800-3300 m) whilst higher (3300-3900 m) and highest elevations (3900-4400 m) are dominated mainly by hemi-cryptophytes and cryptophytes. Our findings further elucidate that vegetation changes gradually from moist-cool temperate Phanerophytic and Chamaephytic elements to dry-cold subalpine and alpine herbaceous Cryptophytic and Hemi-cryptophytic vegetation in the upper elevations. Assessment of life forms and ecological gradient provide a basis for more extensive conservation studies on biodiversity in mountain ecosystems. Our findings further advocate that the Naran Valley appears to be at a transitional floristic position bridging the contrasting moist and dry temperate zones of the Sino-Japanese and Irano-Turanian floristic regions.
D.B Lindenmayer Future Directions For BiodiversityMyris Silva
This document discusses future directions for biodiversity conservation in managed forests. It addresses the indicator species concept, the design of logging impact studies, and the need for long-term monitoring programs. The indicator species concept could help conservation but requires rigorous testing to validate relationships between indicator and target species. Impact studies must consider stand structure rather than just logging history and require sufficient statistical power and scope to detect cumulative effects. Long-term monitoring is critical to inform sustainable forest management but requires long-term funding commitments.
THE EFFECTS OF CLEARCUT SIZE ON THE BIRD COMMUNITY IN THE SECOND COLLEGE GRANTjoshmooney
Abstract. This study examines the effects of forest opening (clearcut) size on the surrounding forest-bird community with the objective of offering management suggestions for foresters who employ the clearcut method. I hypothesized that large and small clearcuts would have different effects on the forest-bird assemblage associated with each. I used the point-count method to assess bird abundance in clearcuts, on the edges, and 100 m into the forest from the edges of large and small clearcuts. I found that Neotropical migrant birds and forest-interior birds were the most affected by large clearcuts showing significantly lower abundance in forest areas 100 m from large clearcut edges than in forest areas 100 m from small clearcuts. Edge-open birds were more abundant in large clearcut openings and edges than in small clearcut openings and edges. Blue jays (an avian nest predator) were more abundant on the edges of large clearcuts than on the edges of small clearcuts. A recent study found that forest-interior bird abundance levels off after 100 m distance from small (0.4 ha) forest openings. This result combined with my findings suggest that small openings in the Second College Grant represent less of a disturbance to Neotropical migrants and forest-interior birds. Additionally, given higher abundances of an avian nest predator in large clearcuts, reproductive success could be much lower in areas associated with large clearcuts. Some species such as the White-throated Sparrow (Zonotrichia albicollis), however preferred large clearcuts suggesting that there are some benefits to overall bird abundance by including large clearcuts in a managed landscape.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This study aimed to develop allometric equations to predict the aboveground biomass of Agave lechuguilla plants in Mexico. Researchers directly measured the biomass of 533 A. lechuguilla plants across three Mexican states by harvesting representative plants and weighing their biomass. They then developed potential and Schumacher-Hall allometric equations relating biomass to plant height and crown diameter measurements. The Schumacher-Hall equation had the best fit and predictive performance. However, including dummy variables revealed population differences between the three states, suggesting separate equations are needed for each state location. The developed equations can help quantify carbon storage in arid and semi-arid regions of Mexico.
Diversity and species composition of mangroves species in Pilar, Siargao Isla...Innspub Net
Mangroves are considered as the most significant components of the coastal ecosystem and among the most productive and biologically complex ecosystems on the planet. Assessment of mangrove species plays a critical role in the preservation and protection of the mangroves forest. The study aimed to assess the mangrove species in Pilar, Siargao Island. The belt transect was employed with a dimension of modified 10 m x 12 m and was installed per quadrat. Eight mangrove species were identified under four families, and these are B. sexanguela, C. decandra, R. apiculata, R. mucronata, A. alba, A. marina, L. littorea, and X. granatum. One species, C. decandra is categorized by the IUCN as a near-threatened state. Results from the mangroves vegetation structure show that R. apiculata got the highest relative frequency (26.32%), density (35.46%), and dominance (55.08%) therefore; it has the highest importance value (116.85%). This further implies that R. apiculata is the most important and acclimated mangrove species in the study area. The species diversity in Pilar, Siargao Island falls under very low diversity (H’=1.63) which might be attributed to some human-related disturbances. Thus, further consideration in future planning and conservation to increase the resiliency of the mangrove ecosystem is needed.
1st European Congress of Conservation Biology, Hungary 2006Dr. Amalesh Dhar
This document evaluates six management strategies for an endangered population of Taxus baccata (English yew) in Austria using population viability risk management (PVRM) and the analytical hierarchy process (AHP). Strategy IV was found to best maintain viability by enhancing genetic variation, improving light availability, and reducing browsing pressure through fencing. A sensitivity analysis showed strategy IV had the highest priority across different scenarios, making it the overall best compromise solution.
Long-term monitoring of diversity and structure of two stands of an Atlantic ...Écio Diniz
This study monitored the diversity and structure of tree communities in two stands (B and C) of an Atlantic tropical forest in southeast Brazil over several years. Stand B was surveyed in 2000, 2005 and 2011, while stand C was surveyed in 2001, 2006 and 2011. The stands differed in their structure, diversity, and species richness over time. The most abundant and important species for biomass accumulation were trees larger than 20 cm in diameter, indicating an advanced successional stage.
Phyto climatic gradient of vegetation and habitat specificity in the high ele...Shujaul Mulk Khan
Phyto-climatic gradient and ecological indicators can be used to understand the requirements, long term management and conservation strategies of natural habitats and species. For this purpose phytosociological attributes were measured using quadrats along transects on different slope aspects across an elevation range of 2450-4400 m. The 198 recorded plant species were placed in five Raunkiaer life form classes among which the Hemicryptophytes (51%) dominate the flora of the study area followed by Phanerophytes and Cryptophytes (Geophytes) with 15 and 13% dominance respectively. Therophytes and Chamaephytes are represented by smaller numbers (12 & 10% each). The phyto-climatic gradient of the vegetation was evaluated using Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA). Phyto-climatic relationships show that Phanerophytes especially tree species are widely distributed on northern aspect slopes whilst shrubs are more dominant on southern aspect slopes. Woody plants are dominant at lower altitudes (2450-2800 m), with a much smaller proportion occurring at middle elevations (2800-3300 m) whilst higher (3300-3900 m) and highest elevations (3900-4400 m) are dominated mainly by hemi-cryptophytes and cryptophytes. Our findings further elucidate that vegetation changes gradually from moist-cool temperate Phanerophytic and Chamaephytic elements to dry-cold subalpine and alpine herbaceous Cryptophytic and Hemi-cryptophytic vegetation in the upper elevations. Assessment of life forms and ecological gradient provide a basis for more extensive conservation studies on biodiversity in mountain ecosystems. Our findings further advocate that the Naran Valley appears to be at a transitional floristic position bridging the contrasting moist and dry temperate zones of the Sino-Japanese and Irano-Turanian floristic regions.
D.B Lindenmayer Future Directions For BiodiversityMyris Silva
This document discusses future directions for biodiversity conservation in managed forests. It addresses the indicator species concept, the design of logging impact studies, and the need for long-term monitoring programs. The indicator species concept could help conservation but requires rigorous testing to validate relationships between indicator and target species. Impact studies must consider stand structure rather than just logging history and require sufficient statistical power and scope to detect cumulative effects. Long-term monitoring is critical to inform sustainable forest management but requires long-term funding commitments.
THE EFFECTS OF CLEARCUT SIZE ON THE BIRD COMMUNITY IN THE SECOND COLLEGE GRANTjoshmooney
Abstract. This study examines the effects of forest opening (clearcut) size on the surrounding forest-bird community with the objective of offering management suggestions for foresters who employ the clearcut method. I hypothesized that large and small clearcuts would have different effects on the forest-bird assemblage associated with each. I used the point-count method to assess bird abundance in clearcuts, on the edges, and 100 m into the forest from the edges of large and small clearcuts. I found that Neotropical migrant birds and forest-interior birds were the most affected by large clearcuts showing significantly lower abundance in forest areas 100 m from large clearcut edges than in forest areas 100 m from small clearcuts. Edge-open birds were more abundant in large clearcut openings and edges than in small clearcut openings and edges. Blue jays (an avian nest predator) were more abundant on the edges of large clearcuts than on the edges of small clearcuts. A recent study found that forest-interior bird abundance levels off after 100 m distance from small (0.4 ha) forest openings. This result combined with my findings suggest that small openings in the Second College Grant represent less of a disturbance to Neotropical migrants and forest-interior birds. Additionally, given higher abundances of an avian nest predator in large clearcuts, reproductive success could be much lower in areas associated with large clearcuts. Some species such as the White-throated Sparrow (Zonotrichia albicollis), however preferred large clearcuts suggesting that there are some benefits to overall bird abundance by including large clearcuts in a managed landscape.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This study aimed to develop allometric equations to predict the aboveground biomass of Agave lechuguilla plants in Mexico. Researchers directly measured the biomass of 533 A. lechuguilla plants across three Mexican states by harvesting representative plants and weighing their biomass. They then developed potential and Schumacher-Hall allometric equations relating biomass to plant height and crown diameter measurements. The Schumacher-Hall equation had the best fit and predictive performance. However, including dummy variables revealed population differences between the three states, suggesting separate equations are needed for each state location. The developed equations can help quantify carbon storage in arid and semi-arid regions of Mexico.
Diversity and species composition of mangroves species in Pilar, Siargao Isla...Innspub Net
Mangroves are considered as the most significant components of the coastal ecosystem and among the most productive and biologically complex ecosystems on the planet. Assessment of mangrove species plays a critical role in the preservation and protection of the mangroves forest. The study aimed to assess the mangrove species in Pilar, Siargao Island. The belt transect was employed with a dimension of modified 10 m x 12 m and was installed per quadrat. Eight mangrove species were identified under four families, and these are B. sexanguela, C. decandra, R. apiculata, R. mucronata, A. alba, A. marina, L. littorea, and X. granatum. One species, C. decandra is categorized by the IUCN as a near-threatened state. Results from the mangroves vegetation structure show that R. apiculata got the highest relative frequency (26.32%), density (35.46%), and dominance (55.08%) therefore; it has the highest importance value (116.85%). This further implies that R. apiculata is the most important and acclimated mangrove species in the study area. The species diversity in Pilar, Siargao Island falls under very low diversity (H’=1.63) which might be attributed to some human-related disturbances. Thus, further consideration in future planning and conservation to increase the resiliency of the mangrove ecosystem is needed.
1st European Congress of Conservation Biology, Hungary 2006Dr. Amalesh Dhar
This document evaluates six management strategies for an endangered population of Taxus baccata (English yew) in Austria using population viability risk management (PVRM) and the analytical hierarchy process (AHP). Strategy IV was found to best maintain viability by enhancing genetic variation, improving light availability, and reducing browsing pressure through fencing. A sensitivity analysis showed strategy IV had the highest priority across different scenarios, making it the overall best compromise solution.
Long-term monitoring of diversity and structure of two stands of an Atlantic ...Écio Diniz
This study monitored the diversity and structure of tree communities in two stands (B and C) of an Atlantic tropical forest in southeast Brazil over several years. Stand B was surveyed in 2000, 2005 and 2011, while stand C was surveyed in 2001, 2006 and 2011. The stands differed in their structure, diversity, and species richness over time. The most abundant and important species for biomass accumulation were trees larger than 20 cm in diameter, indicating an advanced successional stage.
WE1.L09 - DESDYNI BIODIVERSITY AND HABITAT KEY VARIABLES AND IMPLICATIONS FOR...grssieee
This document discusses the use of lidar and radar data from the proposed DESDynI mission to characterize 3D vegetation structure for assessments of biodiversity and habitat. It identifies key variables like canopy height, height profiles, biomass, and cover that influence habitat suitability and have been correlated with species diversity. Fusion of lidar and radar is highlighted as providing more complete and accurate global maps of these important structural metrics compared to either sensor alone. The document concludes that lidar-radar fusion holds promise for advancing scientific understanding of biodiversity patterns in relation to forest structure and how these may change in response to disturbance events.
Climate and potential habitat suitability for cultivation and in situ conserv...Innspub Net
This study used species distribution modeling and representation gap analysis to assess how current and future climates may impact the potential distribution and habitat suitability of Vitex doniana in Benin, West Africa. The MaxEnt algorithm showed V. doniana distribution is strongly influenced by annual rainfall, temperature diurnal range, and temperature of the driest quarter. Under current climate, about 85% of Benin has suitable habitat for its cultivation. Suitable habitat is projected to increase by 3-12% under future climates. Over 75% of protected areas in Benin provide suitable habitat currently, with increases of 14-23% projected. The findings suggest opportunities for integrating V. doniana in agricultural systems and highlight its potential for ecosystem restoration
This document discusses differing approaches to conservation of the Javan gibbon species. Fieldwork focused on reducing habitat destruction through forest management. However, a population analysis focused on low genetic diversity and proposed captive breeding. The author argues conservation biologists must thoroughly analyze problems before solving them, and involve experts from different fields to balance perspectives for effective solutions. Summarizing two key points of disagreement on approaches to Javan gibbon conservation.
Biodiversity of english yew (Taxus baccata L.) populations in AustriaDr. Amalesh Dhar
The document summarizes the findings of a PhD thesis on the biodiversity of English yew populations in Austria. It discusses the current ecological condition, population structure, and genetic variation of yew populations in different locations in Austria. It assessed regeneration levels, diameter distributions, stand structures, and genetic diversity. It evaluated different conservation management strategies using a population viability risk management framework to develop recommendations to improve the monitoring and conservation of yew populations in Austria.
Climatic variability and spatial distribution of herbaceous fodders in the Su...IJERA Editor
This study focused on future spatial distributions of Andropogon gayanus, Loxodera ledermanii and Alysicarpus
ovalifolius regarding bioclimatic variables in the Sudanian zone of Benin, particularly in the W Biosphere
Reserve (WBR). These species were selected according to their importance for animals feed and the
intensification of exploitation pressure induced change in their natural spatial distribution. Twenty (20)
bioclimatic variables were tested and variables with high auto-correlation values were eliminated. Then, we
retained seven climatic variables for the model. A MaxEnt (Maximum Entropy) method was used to identify all
climatic factors which determined the spatial distribution of the three species. Spatial distribution showed for
Andropogon gayanus, a regression of high area distribution in detriment of low and moderate areas. The same
trend was observed for Loxodera ledermannii spatial distribution. For Alysicarpus ovalifolius, currently area
with moderate and low distribution were the most represented but map showed in 2050 that area with high
distribution increased. We can deduce that without bioclimatic variables, others factors such as: biotic
interactions, dispersion constraints, anthropic pressure, human activities and another historic factor determined
spatial distribution of species. Modeling techniques that require only presence data are therefore extremely
valuable.
This document summarizes a study that analyzed fern species richness along an elevational gradient in central Nepal from 100-4800 meters above sea level. The study found a unimodal relationship between species richness and elevation, with the maximum number of fern species occurring at 2000 meters. Fern species richness was found to have a unimodal response to energy gradients and a linear response to moisture gradients. The peak in fern species coincided with elevations that have higher moisture levels due to more rainy days and presence in the cloud zone.
Identifying plant species and communities across environmental gradients in ...Shujaul Mulk Khan
Phytosociological attributes of plant species and associated environmental factors were measured in order to identify the environmental gradients of major plant communities in the Naran Valley, Himalayas. The valley occupies a distinctive geographical setting on the edge of the Western Himalaya near the Hindukush range and supports a high biodiversity; pastoralism is the main land use. There have been no previous quantitative ecological studies in this region. This study was undertaken to (i) analyze and describe vegetation using classification and ordination techniques, (ii) identify environmental gradients responsible for plant community distributions and (iii) assess the anthropogenic pressures on the vegetation and identify priorities for conservation. Phytosociological characteristics of species were measured alongside environmental variables. A total of 198 species from 68 families were quantified at 144 stations along 24 transects across an elevation range of 2450–4100 m. Correspondence Analysis techniques i.e., Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to determine vegetation–environment relationships. Results show vegetation changes with altitude from moist-cool temperate communities characterized by woody species, to more dry-cold subalpine and alpine herbaceous communities. Plant species diversity is optimal at middle altitudes (2800–3400 m); at lower altitudes (2400–2800 m) it is reduced by anthropogenic impacts and at higher altitudes (3400–4100 m) by shallow soils and high summer grazing pressure. A large number of plant species of conservation concern were identified in the study and an assessment made of the main threats to their survival.
A numerical analysis of understory plant associations in a Pinus wallichiana ...Innspub Net
The present investigation describes the structure and vegetation composition of the forest located in Murree Hills, Punjab, Pakistan. The study area is a part of Himalayans moist temperate forest. The vegetation zone entirely consists of shrubs or medium size trees. The plants give the appearance of a vast flower bed, composed principally of herbaceous species. These species are adapted to withstand the extremes of cold and desiccation. Study area range in altitude from 2100m-2300 m (A.S.L.). A total of 65 species, belonging to 62 genera and 39 families were recorded from 40 stands. Angiosperms contributed a major share while Pteridophytes contributed little to the floristic richness of the area. Data were analyzed by multivariate statistics including Cluster Analysis, Detrended Correspondence Analysis (DCA) and correlation co-efficient to detect the relations between altitudinal and some environmental factors with composition and structure of the plant communities. DCA axis 1 and axis 2 were used to interpret the data. Four vegetation types were delineated by Cluster Analysis which was then plotted on the first two axes a scattered diagram. The outcome of the cluster was confirmed by using DCA. There were significant differences in the flora composition as well as the edaphic factors along the altitudinal gradient. The results of the present investigation suggest a direct altitudinal and soil chemical factors pH, EC, cations and anions on the vegetation variation. Topography predicts species composition of the study area.
Pastoralists’ Perceptions towards Rangeland Degradation and Management in Don...AI Publications
Local land users often have different perceptions on the problems of rangeland degradation, compared to researchers and Government officials. This study was aimed at breaching this gap, by empirically exploring pastoralists’ perceptions regarding rangeland degradation in Donga-mantung. The pastoralists’ perceptions were studied through a descriptive statistics method. Focus group discussions, field observations and structured/semi-structured survey questionnaires, were used for data collection, where 200 pastoralists were targeted. The study covered seven Ardorates based on intensity of rangeland degradation (high, medium and less). The major findings indicate that, the main livestock production constraints were Insufficient and poor pasture (50.5%), cattle diseases (24.5%), Farmer/grazer conflicts (14.5%) and insufficient cattle drinking points (10.5%). Majority of respondents (59.5 %) confirmed that cattle population is declining in the study area. According to 59.5% of the respondents, the study area present range condition has deteriorated and become poor. The major causes for degradation were overgrazing, bush encroachment, soil erosion and limited care and attention paid to rangelands. The major socio-economic impacts of rangeland degradation were poverty (51.0%), food insecurity (35.5%) and conflicts (11.0%). The pastoralists of the study area traditionally practice rangeland management in different ways such as bush burning, bush clearing and herd mobility. A proportion of them (41.5%) have adopted the planting of improved pasture(s). Government and NGOs’ supports proved to be limiting in the study area. Nevertheless, the measures perceived by pastoralists to reduce degradation of their rangeland include; planting of improved pastures (40.5%), clearance of bushes that have encroach on rangelands (28.5%), establishing community awareness and community empowerment on rangeland degradation (17.0%), reducing the number of farmlands (9.5%) and reducing soil erosion (4.5%). This study showed the need for rangeland professionals, researchers, planners and other stakeholders to integrate the communities’ perceptions and existing indigenous ecological knowledge to ensure a sustainable rangeland management.
The document describes a decision analysis conducted to evaluate management strategies for controlling the invasive plant crested wheatgrass in Grasslands National Park, Canada. The analysis compared alternative strategies involving different budgets and priorities (treating large existing patches vs. small new populations). It found that under current funding levels, prioritizing early detection and control of new infestations maximized the reduction of crested wheatgrass cover over 50 years. The analysis incorporated uncertainties about the spread and control of crested wheatgrass to identify robust strategies. It concluded such decision analysis approaches could help land managers faced with uncertainty select optimal invasive species control strategies.
This study examines the relationship between fire history and plant biodiversity in dry tropical forests in western Madagascar. Vegetation plots were established across an area stratified by fire intensity, as measured by a burn ratio derived from satellite imagery. Species richness, diversity, and above-ground biomass were measured and compared to the burn ratio. Statistical analysis found significant negative correlations, suggesting fire contributes to degradation of the forest through reduced biomass and lower biodiversity. However, the data are heterogeneous and relationships are weak, warranting cautious interpretation. The research aims to evaluate fire's impacts on the forest to inform conservation efforts in this biodiversity hotspot.
Tree species composition and above ground tree biomass estimationMrumba E. John
This document reports on a study of the tree species composition and above-ground biomass of the Salenda Bridge mangrove patch in Tanzania. Only one mangrove tree species, Avicinnia marina, was found in the study area. Data on tree diameter, height, and frequency was collected from 12 sample plots and used to calculate the above-ground biomass and carbon stock. The estimated above-ground biomass was 458.3 tons/ha and the carbon stock was 221.67 tons/ha. The study concludes the mangrove forest is well-developed with relatively high conservation but recommends further protection, restoration, and additional research.
This study examined the diversity and abundance of fruit-feeding butterflies across four habitat types in a Costa Rican cloud forest: primary forest, natural secondary regrowth forest, planted secondary regrowth forest, and pastureland. The researchers trapped 174 butterflies of 27 species over six weeks. They found that planted secondary regrowth forest had the highest species richness, diversity, and evenness, indicating reforestation efforts were improving diversity. Climate change may be causing butterflies to move to new elevations.
This research paper examines how plant species richness varies along a subtropical elevation gradient in eastern Nepal. The study analyzes species richness data from 1500 to 100 meters above sea level, divided into 15 100-meter elevation bands. Species were counted in standardized plots and assigned to different life forms, including trees, shrubs, climbers, herbs and ferns. Climate variables like potential evapotranspiration and mean annual rainfall were analyzed to explain variations in species richness of different life forms along the elevation gradient. The results found relationships between climate variables and species richness for woody life forms but not for herbaceous life forms. A water-energy dynamics model was found to explain 63-70% of the variation in species richness for
This document summarizes a study that assessed patterns of oak regeneration and carbon storage in relation to forest management, historical land use, and potential trade-offs between the two goals. The study was conducted in an oak-dominated forest in Illinois that had undergone various restoration-focused management regimes including prescribed fire and thinning over at least 20 years. The results showed that live biomass was increasing across the landscape but was not strongly related to differences in management or land use history. Oak regeneration was rare and also not strongly related to recent management. This indicates that current management has failed to create the open canopy conditions needed for successful oak recruitment. No significant trade-offs were found between biomass accrual and oak regeneration, likely because management has
West Fork Timber Company (WFTC) is a private timber company that manages approximately 54,000 acres on the western slopes of the Cascade Mountains. West Fork's goal was to develop a long-term harvest plan that would improve asset value over time, while simultaneously ensuring that habitat requirements set forth in their Habitat Conservation Plan (HCP) would be realized. The primary constraint set forth in the HCP is the maintenance of a unique Dispersal Landscape Index (DLI) within a narrow (+/- 5%) range of pre-determined levels for the life of the HCP. The DLI is derived by assigning different values to areas within specific distances of existing dispersal habitat (DH) in a complex formula; the dispersal habitat (DH) values are then summed and divided by the total number of acres in the forest to arrive at a DLI value for the ownership. This paper discusses DLI calculation and the challenges involved in modeling this problem, including the types of constraints needed in the strategic model, the spatial allocation of activities associated with existing and future stands in a Model II framework, and the development of a rapid DLI calculator to facilitate the evaluation of alternatives. Overall, West Fork was able to meet objective of higher returns from the forest while simultaneously demonstrating improvement in dispersal habitat over the next four decades.
This document summarizes a study on the invasion of alien grasses in Brazilian savannas, known as cerrados. Two alien African grasses, Melinis minutiflora and Brachiaria decumbens, were found to be highly abundant in the study site, with very high importance values. Light availability was found to be the most important environmental factor related to graminoid distribution, strongly correlated with M. minutiflora abundance. Both alien grasses were negatively associated with most native graminoids, suggesting they exert strong competitive pressure on the native herbaceous community. The introduction and spread of alien species poses a threat to the natural biodiversity of cerrados.
Climatic variability and spatial distribution of herbaceous fodders in the Su...IJERA Editor
This study focused on future spatial distributions of Andropogon gayanus, Loxodera ledermanii and Alysicarpus
ovalifolius regarding bioclimatic variables in the Sudanian zone of Benin, particularly in the W Biosphere
Reserve (WBR). These species were selected according to their importance for animals feed and the
intensification of exploitation pressure induced change in their natural spatial distribution. Twenty (20)
bioclimatic variables were tested and variables with high auto-correlation values were eliminated. Then, we
retained seven climatic variables for the model. A MaxEnt (Maximum Entropy) method was used to identify all
climatic factors which determined the spatial distribution of the three species. Spatial distribution showed for
Andropogon gayanus, a regression of high area distribution in detriment of low and moderate areas. The same
trend was observed for Loxodera ledermannii spatial distribution. For Alysicarpus ovalifolius, currently area
with moderate and low distribution were the most represented but map showed in 2050 that area with high
distribution increased. We can deduce that without bioclimatic variables, others factors such as: biotic
interactions, dispersion constraints, anthropic pressure, human activities and another historic factor determined
spatial distribution of species. Modeling techniques that require only presence data are therefore extremely
valuable.
This study examined the effects of soil water temperature on root hydraulic resistance (Rh) in six species of Iberian pines. Rh increased for all species as temperature decreased from 30°C to 0°C. Mountain pine species showed consistently higher Rh values than coastal pine species at all temperatures tested. Mountain pines also displayed a more pronounced increase in Rh in response to decreasing temperatures, with their Rh response curves exhibiting a sharper inflection point between 20-10°C. These differences in hydraulic behavior between mountain and coastal pine species support their observed spatial segregation patterns along altitudinal gradients in the Iberian Peninsula, and may influence how these species respond to future climate change.
This document summarizes a study that compared landscape permeability models to observed puma occurrence data in the Santa Cruz Mountains of California. The models were based on regression analyses of species detection levels from previous studies in relation to landscape features like distance to roads and housing density. The models estimated permeability on a scale of 0 to 1 across the landscape. When compared to 115,384 puma location points, the models showed pumas readily using moderately disturbed areas but rarely using heavily urbanized areas or steep slopes. While generic permeability models can help identify wildlife movement areas when species data is limited, more detailed studies may be needed for accurate connectivity planning in rural landscapes with moderate development.
1) Approximately 51% of households in Cusuco National Park in Honduras are multidimensionally poor, deprived in nearly 45% of basic indicators like electricity, safe water, and assets. Poverty in the park is comparable to rural Honduras.
2) Perceptions of ecosystem services differ between communities in the park, likely due to differences in enforcement of rules and activities. Water provision and climate regulation are highly valued. Agriculture is also important for livelihoods.
3) Community-based management could help address poverty by targeting deprivations, linking conservation to development goals, and providing alternatives to unsustainable land uses and resources like firewood. However, restrictions may reinforce poverty if sustainable alternatives are not
WE1.L09 - DESDYNI BIODIVERSITY AND HABITAT KEY VARIABLES AND IMPLICATIONS FOR...grssieee
This document discusses the use of lidar and radar data from the proposed DESDynI mission to characterize 3D vegetation structure for assessments of biodiversity and habitat. It identifies key variables like canopy height, height profiles, biomass, and cover that influence habitat suitability and have been correlated with species diversity. Fusion of lidar and radar is highlighted as providing more complete and accurate global maps of these important structural metrics compared to either sensor alone. The document concludes that lidar-radar fusion holds promise for advancing scientific understanding of biodiversity patterns in relation to forest structure and how these may change in response to disturbance events.
Climate and potential habitat suitability for cultivation and in situ conserv...Innspub Net
This study used species distribution modeling and representation gap analysis to assess how current and future climates may impact the potential distribution and habitat suitability of Vitex doniana in Benin, West Africa. The MaxEnt algorithm showed V. doniana distribution is strongly influenced by annual rainfall, temperature diurnal range, and temperature of the driest quarter. Under current climate, about 85% of Benin has suitable habitat for its cultivation. Suitable habitat is projected to increase by 3-12% under future climates. Over 75% of protected areas in Benin provide suitable habitat currently, with increases of 14-23% projected. The findings suggest opportunities for integrating V. doniana in agricultural systems and highlight its potential for ecosystem restoration
This document discusses differing approaches to conservation of the Javan gibbon species. Fieldwork focused on reducing habitat destruction through forest management. However, a population analysis focused on low genetic diversity and proposed captive breeding. The author argues conservation biologists must thoroughly analyze problems before solving them, and involve experts from different fields to balance perspectives for effective solutions. Summarizing two key points of disagreement on approaches to Javan gibbon conservation.
Biodiversity of english yew (Taxus baccata L.) populations in AustriaDr. Amalesh Dhar
The document summarizes the findings of a PhD thesis on the biodiversity of English yew populations in Austria. It discusses the current ecological condition, population structure, and genetic variation of yew populations in different locations in Austria. It assessed regeneration levels, diameter distributions, stand structures, and genetic diversity. It evaluated different conservation management strategies using a population viability risk management framework to develop recommendations to improve the monitoring and conservation of yew populations in Austria.
Climatic variability and spatial distribution of herbaceous fodders in the Su...IJERA Editor
This study focused on future spatial distributions of Andropogon gayanus, Loxodera ledermanii and Alysicarpus
ovalifolius regarding bioclimatic variables in the Sudanian zone of Benin, particularly in the W Biosphere
Reserve (WBR). These species were selected according to their importance for animals feed and the
intensification of exploitation pressure induced change in their natural spatial distribution. Twenty (20)
bioclimatic variables were tested and variables with high auto-correlation values were eliminated. Then, we
retained seven climatic variables for the model. A MaxEnt (Maximum Entropy) method was used to identify all
climatic factors which determined the spatial distribution of the three species. Spatial distribution showed for
Andropogon gayanus, a regression of high area distribution in detriment of low and moderate areas. The same
trend was observed for Loxodera ledermannii spatial distribution. For Alysicarpus ovalifolius, currently area
with moderate and low distribution were the most represented but map showed in 2050 that area with high
distribution increased. We can deduce that without bioclimatic variables, others factors such as: biotic
interactions, dispersion constraints, anthropic pressure, human activities and another historic factor determined
spatial distribution of species. Modeling techniques that require only presence data are therefore extremely
valuable.
This document summarizes a study that analyzed fern species richness along an elevational gradient in central Nepal from 100-4800 meters above sea level. The study found a unimodal relationship between species richness and elevation, with the maximum number of fern species occurring at 2000 meters. Fern species richness was found to have a unimodal response to energy gradients and a linear response to moisture gradients. The peak in fern species coincided with elevations that have higher moisture levels due to more rainy days and presence in the cloud zone.
Identifying plant species and communities across environmental gradients in ...Shujaul Mulk Khan
Phytosociological attributes of plant species and associated environmental factors were measured in order to identify the environmental gradients of major plant communities in the Naran Valley, Himalayas. The valley occupies a distinctive geographical setting on the edge of the Western Himalaya near the Hindukush range and supports a high biodiversity; pastoralism is the main land use. There have been no previous quantitative ecological studies in this region. This study was undertaken to (i) analyze and describe vegetation using classification and ordination techniques, (ii) identify environmental gradients responsible for plant community distributions and (iii) assess the anthropogenic pressures on the vegetation and identify priorities for conservation. Phytosociological characteristics of species were measured alongside environmental variables. A total of 198 species from 68 families were quantified at 144 stations along 24 transects across an elevation range of 2450–4100 m. Correspondence Analysis techniques i.e., Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to determine vegetation–environment relationships. Results show vegetation changes with altitude from moist-cool temperate communities characterized by woody species, to more dry-cold subalpine and alpine herbaceous communities. Plant species diversity is optimal at middle altitudes (2800–3400 m); at lower altitudes (2400–2800 m) it is reduced by anthropogenic impacts and at higher altitudes (3400–4100 m) by shallow soils and high summer grazing pressure. A large number of plant species of conservation concern were identified in the study and an assessment made of the main threats to their survival.
A numerical analysis of understory plant associations in a Pinus wallichiana ...Innspub Net
The present investigation describes the structure and vegetation composition of the forest located in Murree Hills, Punjab, Pakistan. The study area is a part of Himalayans moist temperate forest. The vegetation zone entirely consists of shrubs or medium size trees. The plants give the appearance of a vast flower bed, composed principally of herbaceous species. These species are adapted to withstand the extremes of cold and desiccation. Study area range in altitude from 2100m-2300 m (A.S.L.). A total of 65 species, belonging to 62 genera and 39 families were recorded from 40 stands. Angiosperms contributed a major share while Pteridophytes contributed little to the floristic richness of the area. Data were analyzed by multivariate statistics including Cluster Analysis, Detrended Correspondence Analysis (DCA) and correlation co-efficient to detect the relations between altitudinal and some environmental factors with composition and structure of the plant communities. DCA axis 1 and axis 2 were used to interpret the data. Four vegetation types were delineated by Cluster Analysis which was then plotted on the first two axes a scattered diagram. The outcome of the cluster was confirmed by using DCA. There were significant differences in the flora composition as well as the edaphic factors along the altitudinal gradient. The results of the present investigation suggest a direct altitudinal and soil chemical factors pH, EC, cations and anions on the vegetation variation. Topography predicts species composition of the study area.
Pastoralists’ Perceptions towards Rangeland Degradation and Management in Don...AI Publications
Local land users often have different perceptions on the problems of rangeland degradation, compared to researchers and Government officials. This study was aimed at breaching this gap, by empirically exploring pastoralists’ perceptions regarding rangeland degradation in Donga-mantung. The pastoralists’ perceptions were studied through a descriptive statistics method. Focus group discussions, field observations and structured/semi-structured survey questionnaires, were used for data collection, where 200 pastoralists were targeted. The study covered seven Ardorates based on intensity of rangeland degradation (high, medium and less). The major findings indicate that, the main livestock production constraints were Insufficient and poor pasture (50.5%), cattle diseases (24.5%), Farmer/grazer conflicts (14.5%) and insufficient cattle drinking points (10.5%). Majority of respondents (59.5 %) confirmed that cattle population is declining in the study area. According to 59.5% of the respondents, the study area present range condition has deteriorated and become poor. The major causes for degradation were overgrazing, bush encroachment, soil erosion and limited care and attention paid to rangelands. The major socio-economic impacts of rangeland degradation were poverty (51.0%), food insecurity (35.5%) and conflicts (11.0%). The pastoralists of the study area traditionally practice rangeland management in different ways such as bush burning, bush clearing and herd mobility. A proportion of them (41.5%) have adopted the planting of improved pasture(s). Government and NGOs’ supports proved to be limiting in the study area. Nevertheless, the measures perceived by pastoralists to reduce degradation of their rangeland include; planting of improved pastures (40.5%), clearance of bushes that have encroach on rangelands (28.5%), establishing community awareness and community empowerment on rangeland degradation (17.0%), reducing the number of farmlands (9.5%) and reducing soil erosion (4.5%). This study showed the need for rangeland professionals, researchers, planners and other stakeholders to integrate the communities’ perceptions and existing indigenous ecological knowledge to ensure a sustainable rangeland management.
The document describes a decision analysis conducted to evaluate management strategies for controlling the invasive plant crested wheatgrass in Grasslands National Park, Canada. The analysis compared alternative strategies involving different budgets and priorities (treating large existing patches vs. small new populations). It found that under current funding levels, prioritizing early detection and control of new infestations maximized the reduction of crested wheatgrass cover over 50 years. The analysis incorporated uncertainties about the spread and control of crested wheatgrass to identify robust strategies. It concluded such decision analysis approaches could help land managers faced with uncertainty select optimal invasive species control strategies.
This study examines the relationship between fire history and plant biodiversity in dry tropical forests in western Madagascar. Vegetation plots were established across an area stratified by fire intensity, as measured by a burn ratio derived from satellite imagery. Species richness, diversity, and above-ground biomass were measured and compared to the burn ratio. Statistical analysis found significant negative correlations, suggesting fire contributes to degradation of the forest through reduced biomass and lower biodiversity. However, the data are heterogeneous and relationships are weak, warranting cautious interpretation. The research aims to evaluate fire's impacts on the forest to inform conservation efforts in this biodiversity hotspot.
Tree species composition and above ground tree biomass estimationMrumba E. John
This document reports on a study of the tree species composition and above-ground biomass of the Salenda Bridge mangrove patch in Tanzania. Only one mangrove tree species, Avicinnia marina, was found in the study area. Data on tree diameter, height, and frequency was collected from 12 sample plots and used to calculate the above-ground biomass and carbon stock. The estimated above-ground biomass was 458.3 tons/ha and the carbon stock was 221.67 tons/ha. The study concludes the mangrove forest is well-developed with relatively high conservation but recommends further protection, restoration, and additional research.
This study examined the diversity and abundance of fruit-feeding butterflies across four habitat types in a Costa Rican cloud forest: primary forest, natural secondary regrowth forest, planted secondary regrowth forest, and pastureland. The researchers trapped 174 butterflies of 27 species over six weeks. They found that planted secondary regrowth forest had the highest species richness, diversity, and evenness, indicating reforestation efforts were improving diversity. Climate change may be causing butterflies to move to new elevations.
This research paper examines how plant species richness varies along a subtropical elevation gradient in eastern Nepal. The study analyzes species richness data from 1500 to 100 meters above sea level, divided into 15 100-meter elevation bands. Species were counted in standardized plots and assigned to different life forms, including trees, shrubs, climbers, herbs and ferns. Climate variables like potential evapotranspiration and mean annual rainfall were analyzed to explain variations in species richness of different life forms along the elevation gradient. The results found relationships between climate variables and species richness for woody life forms but not for herbaceous life forms. A water-energy dynamics model was found to explain 63-70% of the variation in species richness for
This document summarizes a study that assessed patterns of oak regeneration and carbon storage in relation to forest management, historical land use, and potential trade-offs between the two goals. The study was conducted in an oak-dominated forest in Illinois that had undergone various restoration-focused management regimes including prescribed fire and thinning over at least 20 years. The results showed that live biomass was increasing across the landscape but was not strongly related to differences in management or land use history. Oak regeneration was rare and also not strongly related to recent management. This indicates that current management has failed to create the open canopy conditions needed for successful oak recruitment. No significant trade-offs were found between biomass accrual and oak regeneration, likely because management has
West Fork Timber Company (WFTC) is a private timber company that manages approximately 54,000 acres on the western slopes of the Cascade Mountains. West Fork's goal was to develop a long-term harvest plan that would improve asset value over time, while simultaneously ensuring that habitat requirements set forth in their Habitat Conservation Plan (HCP) would be realized. The primary constraint set forth in the HCP is the maintenance of a unique Dispersal Landscape Index (DLI) within a narrow (+/- 5%) range of pre-determined levels for the life of the HCP. The DLI is derived by assigning different values to areas within specific distances of existing dispersal habitat (DH) in a complex formula; the dispersal habitat (DH) values are then summed and divided by the total number of acres in the forest to arrive at a DLI value for the ownership. This paper discusses DLI calculation and the challenges involved in modeling this problem, including the types of constraints needed in the strategic model, the spatial allocation of activities associated with existing and future stands in a Model II framework, and the development of a rapid DLI calculator to facilitate the evaluation of alternatives. Overall, West Fork was able to meet objective of higher returns from the forest while simultaneously demonstrating improvement in dispersal habitat over the next four decades.
This document summarizes a study on the invasion of alien grasses in Brazilian savannas, known as cerrados. Two alien African grasses, Melinis minutiflora and Brachiaria decumbens, were found to be highly abundant in the study site, with very high importance values. Light availability was found to be the most important environmental factor related to graminoid distribution, strongly correlated with M. minutiflora abundance. Both alien grasses were negatively associated with most native graminoids, suggesting they exert strong competitive pressure on the native herbaceous community. The introduction and spread of alien species poses a threat to the natural biodiversity of cerrados.
Climatic variability and spatial distribution of herbaceous fodders in the Su...IJERA Editor
This study focused on future spatial distributions of Andropogon gayanus, Loxodera ledermanii and Alysicarpus
ovalifolius regarding bioclimatic variables in the Sudanian zone of Benin, particularly in the W Biosphere
Reserve (WBR). These species were selected according to their importance for animals feed and the
intensification of exploitation pressure induced change in their natural spatial distribution. Twenty (20)
bioclimatic variables were tested and variables with high auto-correlation values were eliminated. Then, we
retained seven climatic variables for the model. A MaxEnt (Maximum Entropy) method was used to identify all
climatic factors which determined the spatial distribution of the three species. Spatial distribution showed for
Andropogon gayanus, a regression of high area distribution in detriment of low and moderate areas. The same
trend was observed for Loxodera ledermannii spatial distribution. For Alysicarpus ovalifolius, currently area
with moderate and low distribution were the most represented but map showed in 2050 that area with high
distribution increased. We can deduce that without bioclimatic variables, others factors such as: biotic
interactions, dispersion constraints, anthropic pressure, human activities and another historic factor determined
spatial distribution of species. Modeling techniques that require only presence data are therefore extremely
valuable.
This study examined the effects of soil water temperature on root hydraulic resistance (Rh) in six species of Iberian pines. Rh increased for all species as temperature decreased from 30°C to 0°C. Mountain pine species showed consistently higher Rh values than coastal pine species at all temperatures tested. Mountain pines also displayed a more pronounced increase in Rh in response to decreasing temperatures, with their Rh response curves exhibiting a sharper inflection point between 20-10°C. These differences in hydraulic behavior between mountain and coastal pine species support their observed spatial segregation patterns along altitudinal gradients in the Iberian Peninsula, and may influence how these species respond to future climate change.
This document summarizes a study that compared landscape permeability models to observed puma occurrence data in the Santa Cruz Mountains of California. The models were based on regression analyses of species detection levels from previous studies in relation to landscape features like distance to roads and housing density. The models estimated permeability on a scale of 0 to 1 across the landscape. When compared to 115,384 puma location points, the models showed pumas readily using moderately disturbed areas but rarely using heavily urbanized areas or steep slopes. While generic permeability models can help identify wildlife movement areas when species data is limited, more detailed studies may be needed for accurate connectivity planning in rural landscapes with moderate development.
1) Approximately 51% of households in Cusuco National Park in Honduras are multidimensionally poor, deprived in nearly 45% of basic indicators like electricity, safe water, and assets. Poverty in the park is comparable to rural Honduras.
2) Perceptions of ecosystem services differ between communities in the park, likely due to differences in enforcement of rules and activities. Water provision and climate regulation are highly valued. Agriculture is also important for livelihoods.
3) Community-based management could help address poverty by targeting deprivations, linking conservation to development goals, and providing alternatives to unsustainable land uses and resources like firewood. However, restrictions may reinforce poverty if sustainable alternatives are not
The current distribution of the endangered Mexican beech [ Fagus grandifolia var. mexicana (Martinez) Little] is restricted to
relict isolated populations in small remnants of montane cloud forest in northeastern Mexico, and little is known about its associated
biota. We sampled bolete diversity in two of these monospecifi c forests in the state of Hidalgo, Mexico. We compared alpha
diversity, including species richness and ensemble structure, and analyzed beta diversity (dissimilarity in species composition)
between forests. We found 26 bolete species, fi ve of which are probably new. Species diversity and evenness were similar between
forests. Beta diversity was low, and the similarities of bolete samples from within and between forests were not signifi cantly different.
These results support the idea that the two forests share a single bolete ensemble with a common history. In contrast,
cumulative species richness differed between the forests, implying that factors other than the mere presence of the host species
have contributed to shaping the biodiversity of ectomycorrhizal fungi in relict Mexican beech forests.
Key words: beta diversity; Boletaceae; community ecology; conservation; Fagaceae; Fagus grandifolia var. mexicana ; Hidalgo;
Mexico; montane cloud forest; species richness.
The current distribution of the endangered Mexican beech [ Fagus grandifolia var. mexicana (Martinez) Little] is restricted to
relict isolated populations in small remnants of montane cloud forest in northeastern Mexico, and little is known about its associated
biota. We sampled bolete diversity in two of these monospecifi c forests in the state of Hidalgo, Mexico. We compared alpha
diversity, including species richness and ensemble structure, and analyzed beta diversity (dissimilarity in species composition)
between forests. We found 26 bolete species, fi ve of which are probably new. Species diversity and evenness were similar between
forests. Beta diversity was low, and the similarities of bolete samples from within and between forests were not signifi cantly different.
These results support the idea that the two forests share a single bolete ensemble with a common history. In contrast,
cumulative species richness differed between the forests, implying that factors other than the mere presence of the host species
have contributed to shaping the biodiversity of ectomycorrhizal fungi in relict Mexican beech forests.
Key words: beta diversity; Boletaceae; community ecology; conservation; Fagaceae; Fagus grandifolia var. mexicana ; Hidalgo;
Mexico; montane cloud forest; species richness.
We studied the diversity of bolete mushrooms in two isolated, relict forests dominated by the endangered Mexican beech tree in Mexico. We found 26 bolete species total, with similar diversity within each forest but differences in cumulative diversity between forests. This suggests the bolete communities share a common history but local factors also influence diversity. Conserving these rare forests protects not only the trees but also the symbiotic fungi critical to the ecosystem.
ECOLOGY, BEHAVIOR AND BIONOMICSEucalyptus Edge Effect on QEvonCanales257
ECOLOGY, BEHAVIOR AND BIONOMICS
Eucalyptus Edge Effect on Quercus-Herbivore Interactions
in a Neotropical Temperate Forest
C HERNÁNDEZ-SANTIN1, M CUAUTLE1 , M DE LAS N BARRANCO-LEÓN2, J GARCÍA-GUZMÁN1, El BADANO2,
F LUNA-CASTELLANOS1
1Depto de Ciencias Químico Biológicas, Univ de las Américas Puebla, Cholula, Puebla, Mexico
2División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica, San Luis Potosí, Mexico
AbstractKeywords
Quercus , herbivory, edge effect,
Lepidoptera caterpillars
Correspondence
M Cuautle, Depto de Ciencias Químico
Biológicas, Univ de las Américas Puebla,
Cholula, Puebla, Mexico; [email protected]
hotmail.com
Edited by Martin F Pareja – UNICAMP
Received 18 June 2018 and accepted 26
April 2019
* Sociedade Entomológica do Brasil 2019
Fragmentation leads to the formation of edges between habitats, which in
turn changes biotic and abiotic factors that might influence herbivory or
plant-herbivory interactions. The aims of this study were to describe the
herbivory community associated with oak (Quercus) and to determine the
effects of proximity to a Eucalyptus edge and season on insect herbivory.
We selected three forest sites that were subsequently divided into three
quadrants located at different distances from the Eucalyptus edge: edge
(0 m), intermediate (30 m), and oak forest interior (60 m). We randomly
selected 10 oak trees per quadrant and conducted monthly surveys, during
the dry and rainy season (from February to October 2010), where we
quantified leaf area and the percentage of herbivory. These were analyzed
using linear mixed models, with distance and season as fixed factors and
individual and site as random factors. The primary oak herbivores were
Lepidoptera caterpillars. We found that herbivory increased away from
the edge but just during the rainy season, although higher herbivory levels
were found during the dry season. These results seem to be related to a
specialist community of herbivorous associated to the Quercus. This study
emphasizes the importance of considering border effect, especially within
Natural Protected Areas to establish strategies to improve and maintain
native oak forest and the biodiversity of its Lepidoptera herbivorous
community.
Introduction
Landscape modification due to anthropogenic activities (e.g.,
land conversion to agricultural or livestock) has resulted in
habitat fragmentation, one of the major threats for forest
conservation (Buckley 2000, Franklin et al 2002).
Fragmentation is defined as the disruption or breakdown of
large vegetation patches into smaller ones resulting in a dis-
continuity of resource distribution that affects species occu-
pancy, reproduction, and/or survival (Franklin et al 2002).
One of the important features of this phenomenon is an
increase in edge length relative to the forest area, particular-
ly in small habitat fragments (Laurance 1991, Laurance &
Yensen 1991, Murcia 1995, Laurance et al 2007, De
Carvalho ...
Climate Increases Regional Tree Growth Variability In Iberian Pine ForestsHibrids
This study analyzed tree ring width data from 38 pine forest sites across the Iberian Peninsula to examine changes in tree growth patterns and climate response over time. Principal component analysis identified a common macroclimatic signal shared among the tree chronologies. Tree growth variability, the frequency of narrow rings, and interannual growth sensitivity increased markedly in the second half of the 20th century, indicating that climate had a stronger limiting effect on growth. A shift was also detected around the mid-20th century, with growth becoming more strongly correlated with late summer/autumn temperatures of the previous year. This suggests increased water stress may be linked to higher growth synchronization among sites driven by climate changes.
Application of remote sensing in forest ecosystemaliya nasir
Established remote sensing systems provide opportunities to develop and apply new measurements of ecosystem function across landscapes, regions and continents.
New efforts to predict the consequences of ecosystem function change, both natural and human- induced, on the regional and global distributions and abundances of species should be a high research priority
Impacts of fires on the woody stratum of Mbam and Djerem National Park (Camer...AI Publications
In Cameroon, the recurrent and uncontrolled use of bush fires, causing damage to the ecosystem, and constitutes a worrying situation for protected area managers. . The Mbam et Djerem National Park (PNMD) is threatened by bush fires and particularly by uncontrolled late fires which compromise all of its biodiversity and the future of the park. Faced with this increasingly high occurrence of fires and the insufficiency of basic data, it becomes urgent to assess the impacts of fire on the woody and grassy stratum according to the fire regime and at the end of proposing fire management strategies at PNMD level. To do this, experimental plots were installed, the impacts of fire on vegetation according to fire regimes were assessed. The results reveal that: 74% of the trees examined are barked by fire and the proportion of these barked trees varies according to the species of tree, which constitutes entry points for termites and bees in the trees. Adults are significantly more skinned (70%) than young people (30%) (variance = 32.447 df = 1, χ2 = 103.014, p = 0.004). The intensity of the fire is significantly different from one fire regime to another (p = 0.0154). The rate of regrowth is different between treatments (ANOVA, p = 0.005). High (apparent) mortality is observed for class 2 individuals (35%), i.e. juveniles suffering from late fires. Remote sensing therefore appears to be a more valuable tool for monitoring and analyzing space and time for strategic and operational planning and for early warning in the management of bush fires.
Measuring Individual Tree Height and Crown Diameter for Mangrove Trees with A...INFOGAIN PUBLICATION
Mangroves are unique ecosystems that provide valuable coastal area habitats, protection, and services. Access to observing mangrove forests is typically difficult on the ground. Therefore, it is of interest to develop and evaluate remote sensing methods that enable us to obtain accurate information on the structure of mangrove forests and to monitor their condition in time. The main objective of this study was to develop a methodology for processing airborne lidar data for measuring height and crown diameter for mangrove forests in the north-eastern coastal areas of Brazil. Specific objectives were to: (1) evaluate the most appropriate lidar data processing approach, such as area-based or individual tree methods, (2) investigate the most appropriate parameters for lidar-derived data products when estimating height and crown diameter, such as the spatial resolution of canopy height models and ground elevation models; and (3) compare the accuracy of lidar estimates to field measurements of height and crown diameter. The lidar dataset was acquired over mangrove forest of the northeast of Brazil. The crown diameter was calculated as the average of two values measured along two perpendicular directions from the location of each tree top by fitting a fourth-degree polynomial on both profiles. The lidar-derived tree measurements were used with regression models and cross-validation to estimate plot level field-measured crown diameter. Root mean square error, linear regression and the Nash-Sutcliffe coefficient were also used to compare lidar height and field height. The mean of lidar-estimated tree height was 9,48m and the mean of field tree height was 8.44m. The correlation between lidar tree height and field tree height was r= 0.60, E=-0.06 and RMSE= 2.8. The correlation between height and crown diameter needed to parameterized the individual tree identification software obtained for 32 trees was r= 0.83 and determination coefficient was r2 = 0.69. The results of the current study show that lidar data could be used to estimate height and average crown diameter of mangrove trees and to improve estimates of other mangrove forest biophysical parameters of interest by focusing at the individual tree level. The research presented in this study contributes to the overall knowledge of using lidar remote sensing to measure and monitor mangrove forests.
Measuring Individual Tree Height and Crown Diameter for Mangrove Trees with A...INFOGAIN PUBLICATION
Mangroves are unique ecosystems that provide valuable coastal area habitats, protection, and services. Access to observing mangrove forests is typically difficult on the ground. Therefore, it is of interest to develop and evaluate remote sensing methods that enable us to obtain accurate information on the structure of mangrove forests and to monitor their condition in time. The main objective of this study was to develop a methodology for processing airborne lidar data for measuring height and crown diameter for mangrove forests in the north-eastern coastal areas of Brazil. Specific objectives were to: (1) evaluate the most appropriate lidar data processing approach, such as area-based or individual tree methods, (2) investigate the most appropriate parameters for lidar-derived data products when estimating height and crown diameter, such as the spatial resolution of canopy height models and ground elevation models; and (3) compare the accuracy of lidar estimates to field measurements of height and crown diameter. The lidar dataset was acquired over mangrove forest of the northeast of Brazil. The crown diameter was calculated as the average of two values measured along two perpendicular directions from the location of each tree top by fitting a fourth-degree polynomial on both profiles. The lidar-derived tree measurements were used with regression models and cross-validation to estimate plot level field-measured crown diameter. Root mean square error, linear regression and the Nash-Sutcliffe coefficient were also used to compare lidar height and field height. The mean of lidar-estimated tree height was 9,48m and the mean of field tree height was 8.44m. The correlation between lidar tree height and field tree height was r= 0.60, E=-0.06 and RMSE= 2.8. The correlation between height and crown diameter needed to parameterized the individual tree identification software obtained for 32 trees was r= 0.83 and determination coefficient was r2 = 0.69. The results of the current study show that lidar data could be used to estimate height and average crown diameter of mangrove trees and to improve estimates of other mangrove forest biophysical parameters of interest by focusing at the individual tree level. The research presented in this study contributes to the overall knowledge of using lidar remote sensing to measure and monitor mangrove forests.
Measuring Individual Tree Height and Crown Diameter for Mangrove Trees with A...INFOGAIN PUBLICATION
Mangroves are unique ecosystems that provide valuable coastal area habitats, protection, and services. Access to observing mangrove forests is typically difficult on the ground. Therefore, it is of interest to develop and evaluate remote sensing methods that enable us to obtain accurate information on the structure of mangrove forests and to monitor their condition in time. The main objective of this study was to develop a methodology for processing airborne lidar data for measuring height and crown diameter for mangrove forests in the north-eastern coastal areas of Brazil. Specific objectives were to: (1) evaluate the most appropriate lidar data processing approach, such as area-based or individual tree methods, (2) investigate the most appropriate parameters for lidar-derived data products when estimating height and crown diameter, such as the spatial resolution of canopy height models and ground elevation models; and (3) compare the accuracy of lidar estimates to field measurements of height and crown diameter. The lidar dataset was acquired over mangrove forest of the northeast of Brazil. The crown diameter was calculated as the average of two values measured along two perpendicular directions from the location of each tree top by fitting a fourth-degree polynomial on both profiles. The lidar-derived tree measurements were used with regression models and cross-validation to estimate plot level field-measured crown diameter. Root mean square error, linear regression and the Nash-Sutcliffe coefficient were also used to compare lidar height and field height. The mean of lidar-estimated tree height was 9,48m and the mean of field tree height was 8.44m. The correlation between lidar tree height and field tree height was r= 0.60, E=-0.06 and RMSE= 2.8. The correlation between height and crown diameter needed to parameterized the individual tree identification software obtained for 32 trees was r= 0.83 and determination coefficient was r2 = 0.69. The results of the current study show that lidar data could be used to estimate height and average crown diameter of mangrove trees and to improve estimates of other mangrove forest biophysical parameters of interest by focusing at the individual tree level. The research presented in this study contributes to the overall knowledge of using lidar remote sensing to measure and monitor mangrove forests.
1) The study analyzed patterns of beta diversity in dung beetle communities across three spatial scales - local (between sites), intermediate (between areas), and regional (between mainland and island) in the Brazilian Atlantic Forest.
2) Beta diversity was highest at the regional scale between mainland and island, followed by the local scale between sites. Beta diversity was lowest between areas.
3) Environmental heterogeneity had more influence on beta diversity at smaller local scales, while spatial factors were more important drivers at larger intermediate and regional scales likely due to limitations in species dispersal abilities.
The document discusses various wilderness areas around the world and issues relating to their protection. It mentions areas like Antarctica, Clayoquot Sound, and indigenous lifestyles within wilderness regions. There is increasing pressure on wilderness environments from factors like resource exploitation, development, and tourism. Effective strategies are needed to manage these pressures and protect the fragile ecosystems and global importance of wilderness areas.
Article - Vegetation ecology of the Nooitgedacht section of Loskop Dam Nature...Sellina Nkosi
This study classified and mapped the vegetation of the Nooitgedacht section of Loskop Dam Nature Reserve in South Africa. Eleven plant communities were identified through classification of 170 vegetation plots. These communities include wetlands, riverine woodlands, grasslands, and represent both open and closed woodland areas. Species diversity was highest in plant communities 5 and 6. A vegetation map was produced showing the distribution of the plant communities across the study area.
The document analyzes patterns of beta diversity in dung beetle communities across multiple spatial scales in the Brazilian Atlantic Forest. It finds that:
1) Beta diversity is highest at the local scale among sampling sites and regional scale between the mainland and island, driven by environmental heterogeneity and dispersal limitations respectively.
2) Variation in species composition is most influenced by environmental factors at small scales and spatial factors at larger scales.
3) Altitude is a major driver of species distribution, with composition associated with the altitude gradient at all scales.
Exploration of the Ecological Niche of Chacoan Species in Environmental SpaceAlejandro Manuel Ferreiro
This document explores the ecological niches of four species predominantly found in the Chaco region - Bulnesia sarmientoi, Calomys callosus, Leptodactylus bufonius, and Tolypeutes matacus - by modeling their niches in environmental space. It finds that L. bufonius and T. matacus have broader niches while B. sarmientoi and C. callosus have narrower niches. Additionally, all species' niches show some overlap, with an area of environmental space where all four species' niches overlap. Modeling species' niches in environmental space provides new insights into the biogeography of species in the Chaco
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Download the Latest OSHA 10 Answers PDF : oyetrade.comNarendra Jayas
Latest OSHA 10 Test Question and Answers PDF for Construction and General Industry Exam.
Download the full set of 390 MCQ type question and answers - https://www.oyetrade.com/OSHA-10-Answers-2021.php
To Help OSHA 10 trainees to pass their pre-test and post-test we have prepared set of 390 question and answers called OSHA 10 Answers in downloadable PDF format. The OSHA 10 Answers question bank is prepared by our in-house highly experienced safety professionals and trainers. The OSHA 10 Answers document consists of 390 MCQ type question and answers updated for year 2024 exams.
Monitor indicators of genetic diversity from space using Earth Observation dataSpatial Genetics
Genetic diversity within and among populations is essential for species persistence. While targets and indicators for genetic diversity are captured in the Kunming-Montreal Global Biodiversity Framework, assessing genetic diversity across many species at national and regional scales remains challenging. Parties to the Convention on Biological Diversity (CBD) need accessible tools for reliable and efficient monitoring at relevant scales. Here, we describe how Earth Observation satellites (EO) make essential contributions to enable, accelerate, and improve genetic diversity monitoring and preservation. Specifically, we introduce a workflow integrating EO into existing genetic diversity monitoring strategies and present a set of examples where EO data is or can be integrated to improve assessment, monitoring, and conservation. We describe how available EO data can be integrated in innovative ways to support calculation of the genetic diversity indicators of the GBF monitoring framework and to inform management and monitoring decisions, especially in areas with limited research infrastructure or access. We also describe novel, integrative approaches to improve the indicators that can be implemented with the coming generation of EO data, and new capabilities that will provide unprecedented detail to characterize the changes to Earth’s surface and their implications for biodiversity, on a global scale.
A Comprehensive Guide on Cable Location Services Detections Method, Tools, an...Aussie Hydro-Vac Services
Explore Aussie Hydrovac's comprehensive cable location services, employing advanced tools like ground-penetrating radar and robotic CCTV crawlers for precise detection. Also offering aerial surveying solutions. Contact for reliable service in Australia.
The modification of an existing product or the formulation of a new product to fill a newly identified market niche or customer need are both examples of product development. This study generally developed and conducted the formulation of aramang baked products enriched with malunggay conducted by the researchers. Specifically, it answered the acceptability level in terms of taste, texture, flavor, odor, and color also the overall acceptability of enriched aramang baked products. The study used the frequency distribution for evaluators to determine the acceptability of enriched aramang baked products enriched with malunggay. As per sensory evaluation conducted by the researchers, it was proven that aramang baked products enriched with malunggay was acceptable in terms of Odor, Taste, Flavor, Color, and Texture. Based on the results of sensory evaluation of enriched aramang baked products proven that three (3) treatments were all highly acceptable in terms of variable Odor, Taste, Flavor, Color and Textures conducted by the researchers.
Emerging Earth Observation methods for monitoring sustainable food productionCIFOR-ICRAF
Presented by Daniela Requena Suarez, Helmholtz GeoResearch Center Potsdam (GFZ) at "Side event 60th sessions of the UNFCCC Subsidiary Bodies - Sustainable Bites: Innovating Low Emission Food Systems One Country at a Time" on 13 June 2024
Exploring low emissions development opportunities in food systemsCIFOR-ICRAF
Presented by Christopher Martius (CIFOR-ICRAF) at "Side event 60th sessions of the UNFCCC Subsidiary Bodies - Sustainable Bites: Innovating Low Emission Food Systems One Country at a Time" on 13 June 2024
Trichogramma spp. is an efficient egg parasitoids that potentially assist to manage the insect-pests from the field condition by parasiting the host eggs. To mass culture this egg parasitoids effectively, we need to culture another stored grain pest- Rice Meal Moth (Corcyra Cephalonica). After rearing this pest, the eggs of Corcyra will carry the potential Trichogramma spp., which is an Hymenopteran Wasp. The detailed Methodologies of rearing both Corcyra Cephalonica and Trichogramma spp. have described on this ppt.
2. Forests 2021, 12, 385 2 of 18
Twelve of the 19 known species of bark beetles are found in Mexico [8,14]. Dendroc-
tonus mexicanus Hopkins is the most widely distributed in the country [14] and the most
destructive. Because of the irreversible damage it causes to coniferous forests, it is consid-
ered the most important species [15]. It is characterized by high polyphagia, colonizing
over 21 species of pine. Pinus leiophylla Schl. Cham., Pinus teocote Schiede ex Schltdl.
and Pinus devoniana Lindley are the preferred species and those of the highest incidence
percentage [14].
To manage the future of a country’s forests, it is necessary to determine the impact
of climate change on species distribution. Niche-based, correlative species distribution
models (hereafter SDMs) have been widely used to predict the potential changes in species
distributions under climate change scenarios [16–18]. Developing an SDM requires previ-
ous knowledge of the conceptual framework [19–21], ecological assumptions on which to
base species distribution [16,22,23], and of the performance of modeling algorithms [24,25].
Modeling requires records (presence/absence) of the species, predictive variables (e.g.,
bioclimatic [26], topographic [27], soils [28], among others), and of course, the algorithm.
In other words, species distribution is determined by three limiting factors: the geographi-
cal region that has been accessible to the species over a given period of time «M», abiotic
conditions «A» and biotic interactions «B», simplified in the «BAM» diagram [29]. Predic-
tive mapping results in a spatially explicit “wall-to-wall” prediction of species distribution
or habitat suitability [24]. If the fit is good, it is possible to identify the species environ-
mental tolerance and transfer the model in time or space [22]. Although there are several
modeling algorithms, it has been demonstrated that Maxent performs better than standard
methods; it is one of the most efficient and, therefore, the most widely used [25].
Climate change has made us reflect on possible species re-distribution. Effort is
required to understand the dynamics of ecological niches of two or more species (e.g.,
niche shifts, niche conservatism and niche similarity). A niche is defined as the set of
environments suitable to a species [30]. The development of ecological niche models
(hereafter ENMs) makes it possible to quantify niche overlap of species, but also shift,
stability, centroid and niche unfilling [20,31]. Some authors [18] have shown that due to the
effects of climate change, especially temperature, D. mexicanus could modify its distribution
towards higher latitudes and altitudes.
Species suitability models have been used to many ends, commonly for conservation
and biodiversity plans. However, for the case of the genus Pinus in Mexico, they are not
of much use if models of climate suitability of the genus Dendroctonus are not considered
since they coexist partially or totally sharing geographical (G) and environmental (E) space.
Although much has been gained by generating species suitability models and niche models,
it is essential to perform statistical tests to interpret the significance of these patterns. Thus,
for the SDM objective in Pinus to be possible, it is necessary to have precise, reliable
predictions for suitable areas of Pinus (SAP), free of suitable areas of Dendroctonus (SAD) in
order to implement management and conservation strategies integrally.
The objectives of this study were: (i) to generate robust ecological niche and species dis-
tribution models for D. mexicanus and three of its most important host species: P. leiophylla,
P. teocote and P. devoniana, and with these determine SAP free of SAD; (ii) to evaluate the
overlap of climate suitability and of the environmental niche of the association Dendroctonus–
Pinus in spaces G and E by means of predictive models and multivariate analysis, and (iii)
to determine their climate tolerances using a detailed bioclimatic profile of these species.
2. Materials and Methods
The conifer species P. leiophylla, P. teocote and P. devoniana were selected because they
have the highest percentual incidence of bark beetle D. mexicanus attack in Mexico and are
the most susceptible species, with 35.6, 13.9 and 9.4%, respectively [14].
3. Forests 2021, 12, 385 3 of 18
2.1. Study Area
The study area differs for each of the species; in general, there are coniferous forests
located in the main mountain systems of Mexico, such as the Sierra Madre Occidental
(SMOc), Sierra Madre Oriental (SMOr), Trans-Mexico Volcanic Belt (TMVB), Sierra Madre
del Sur, Sierra del Norte de Oaxaca, Sierras de Chiapas, and the extremes of Baja California.
In these regions annual mean temperatures oscillate between 10 and 20 ◦C, and annual
precipitation is 600 to 1000 mm [4]; altitudes are from 1600 m to a little more than 3000 m
(Figure 1).
2. Materials and Methods
The conifer species P. leiophylla, P. teocote and P. devoniana were selected because
they have the highest percentual incidence of bark beetle D. mexicanus attack in Mexico
and are the most susceptible species, with 35.6, 13.9 and 9.4%, respectively [14].
2.1. Study Area
The study area differs for each of the species; in general, there are coniferous for-
ests located in the main mountain systems of Mexico, such as the Sierra Madre Occi-
dental (SMOc), Sierra Madre Oriental (SMOr), Trans-Mexico Volcanic Belt (TMVB), Si-
erra Madre del Sur, Sierra del Norte de Oaxaca, Sierras de Chiapas, and the extremes
of Baja California. In these regions annual mean temperatures oscillate between 10 and
20 °C, and annual precipitation is 600 to 1000 mm [4]; altitudes are from 1600 m to a
little more than 3000 m (Figure 1).
Figure 1. Study area that includes temperate forests.
2.2. Bioclimatic Variables and Selection
Because of the scale of the study area (200 km), only bioclimatic variables were
used (Table 1) [23,32]; these proposed by [33] were re-sampled at a resolution of ∼5
km2. Bio 8, Bio 9, Bio 18 and Bio 19 were excluded from the analysis since, by combining
information on precipitation and temperature in the same layer, the resulting predic-
tions were erratic and biased [34].
Table 1. Contribution of the bioclimatic variables determined by principal component analysis for their preselection
and accommodation in different sets to conduct the species climate suitability modeling tests.
Variable Name Description Species
Dendroctonus mexicanus Pinus leiophylla Pinus teocote Pinus devoniana
PC1 (48.7) PC2 (18.9) PC1 (43.9) PC2 (29.5) PC1 (39.6) PC2 (26.0) PC1 (35.0) PC2 (29.1)
Bio 1 Annual Mean Temperature¶ (°C) 11.44 (3) 14.61 (3) 15.13 15.75[3]
Bio 2 Annual Mean Diurnal Range¶ (°C) 3.97 11.24 (1,2,3)
13.50 8.19
Bio 3 Isothermality (%) 7.04 (1) 13.20 (2) 7.70 3.35
Bio 4 Temperature Seasonality (%) 9.99 14.23 13.41(1,2,3) 7.68 (1,2,3)
Bio 5 Max Temperature of Warmest Month¶ (°C) 9.08 7.58 (1) 13.31 12.28
Bio 6 Min Temperature of Coldest Month¶ (°C) 14.87 (2) 9.82 (2) 12.36 (1,2,3)
20.08 (2)
Bio 7 Annual Temperature Range¶ (°C) 8.18 14.33 [1,3] 14.86 (1,2,3) 9.24 (1,2,3)
Bio 10 Mean Temperature of Warmest Quarter¶ (°C) 9.85 (1,2,3)
9.83 (2) 14.42 (1,2) 11.40
Bio 11 Mean Temperature of Coldest Quarter¶ (°C) 16.43 (1) 9.36 (1) 10.31 (1,2,3)
18.83 (1)
Bio 12 Annual Precipitation (mm) 17.59 9.01 (1,2,3) 7.62 (1,2,3) 13.59 (1,2,3)
Bio 13 Precipitation of Wettest Month (mm) 14.70 7.48 4.00 5.88
Bio 14 Precipitation of Driest Month (mm) 6.00 12.70 10.54 10.43
Bio 15 Precipitation Seasonality (CV, %) 9.15 (1,3)
4.53 (1) 4.43 (1) 4.56
Bio 16 Precipitation of Wettest Quarter (mm) 15.04 (1,2,3)
6.56 3.54 5.99
Bio 17 Precipitation of Driest Quarter (mm) 6.68 13.88 11.10 10.80
Note: PC = principal component; in parentheses, the variance explained is indicated in %, (1,2,3) = set number, indicating
the reaccomodation of the bioclimatic variable in the corresponding set. ¶ = values × 10.
Figure 1. Study area that includes temperate forests.
2.2. Bioclimatic Variables and Selection
Because of the scale of the study area (200 km), only bioclimatic variables were used
(Table 1) [23,32]; these proposed by [33] were re-sampled at a resolution of ∼5 km2. Bio 8,
Bio 9, Bio 18 and Bio 19 were excluded from the analysis since, by combining information
on precipitation and temperature in the same layer, the resulting predictions were erratic
and biased [34].
The selection of the bioclimatic variables was based on four criteria: (1) relative contri-
bution of the variable to the bioclimatic profile of the species [35] was obtained through
a principal components analysis (PCA) with the package ‘FactoMiner’ [36], previously
extracting from each species occurrence records the value of the 15 bioclimatic variables,
making the PCA to the standardized variables and selecting those that contributed most,
(2) non-correlated variables (r 0.8) were determined by a parametric correlation anal-
ysis (α = 0.05) of the variables transformed to natural logarithm [25,37,38], (3) variable
frequency distribution using the Sturges [39] rule determined how the bioclimatic variable
was distributed giving selection priority to those close to a normal distribution or a skewed
distribution (left or right) [40], and (4) the predictive capacity of the variable consists of
preliminary modeling with individual variables and transferring the model in time and
space because it has been demonstrated that climate projections of precipitation of the
General Circulation Models (GCMs) are biased at higher latitudes [33], resulting in an
overestimation of climate suitability of a species in the same zones. The variables that least
overestimate climate suitability of a species were selected. These procedures were carried
out in each species.
4. Forests 2021, 12, 385 4 of 18
Table 1. Contribution of the bioclimatic variables determined by principal component analysis for their preselection and
accommodation in different sets to conduct the species climate suitability modeling tests.
Variable
Name
Description Species
Dendroctonus
mexicanus
Pinus leiophylla Pinus teocote Pinus devoniana
PC1
(48.7)
PC2
(18.9)
PC1
(43.9)
PC2
(29.5)
PC1
(39.6)
PC2
(26.0)
PC1
(35.0)
PC2
(29.1)
Bio 1
Annual Mean
Temperature¶ (◦C)
11.44 (3) 14.61 (3) 15.13 15.75 (3)
Bio 2
Annual Mean
Diurnal Range¶
(◦C)
3.97
11.24
(1,2,3) 13.50 8.19
Bio 3 Isothermality (%) 7.04 (1) 13.20 (2) 7.70 3.35
Bio 4
Temperature
Seasonality (%)
9.99 14.23
13.41
(1,2,3) 7.68 (1,2,3)
Bio 5
Max Temperature
of Warmest
Month¶ (◦C)
9.08 7.58 (1) 13.31 12.28
Bio 6
Min Temperature
of Coldest Month¶
(◦C)
14.87 (2) 9.82 (2) 12.36
(1,2,3) 20.08 (2)
Bio 7
Annual
Temperature
Range¶ (◦C)
8.18 14.33 (1,3) 14.86
(1,2,3) 9.24 (1,2,3)
Bio 10
Mean Temperature
of Warmest
Quarter¶ (◦C)
9.85 (1,2,3) 9.83 (2) 14.42 (1,2) 11.40
Bio 11
Mean Temperature
of Coldest
Quarter¶ (◦C)
16.43 (1) 9.36 (1) 10.31
(1,2,3) 18.83 (1)
Bio 12
Annual
Precipitation (mm)
17.59 9.01 (1,2,3) 7.62 (1,2,3) 13.59
(1,2,3)
Bio 13
Precipitation of
Wettest Month
(mm)
14.70 7.48 4.00 5.88
Bio 14
Precipitation of
Driest Month (mm)
6.00 12.70 10.54 10.43
Bio 15
Precipitation
Seasonality (CV, %)
9.15 (1,3) 4.53 (1) 4.43 (1) 4.56
Bio 16
Precipitation of
Wettest Quarter
(mm)
15.04
(1,2,3) 6.56 3.54 5.99
Bio 17
Precipitation of
Driest Quarter
(mm)
6.68 13.88 11.10 10.80
Note: PC = principal component; in parentheses, the variance explained is indicated in %, (1,2,3) = set number, indicating the reaccomodation
of the bioclimatic variable in the corresponding set. ¶ = values × 10.
2.3. Species Occurrence Records and Cleaning
Species occurrence records of each species were downloaded from the Global Biodi-
versity Information Facility (GBIF) and Red Mundial de Información sobre Biodiversidad
(REMIB). Others were obtained by Inventario Nacional Forestal y de Suelos de México
(INFyS), published articles and our own fieldwork.
Data cleaning of each specie consisted of eliminating records that were: (1) Outside
the geographic range (latitude and longitude), (2) outside the altitudinal range (according
to the descriptor of the species), allowing records between quantile 5 and 95 (and/or
±500 m), depending on the species, (3) not precise (equal to or less than three digits),
5. Forests 2021, 12, 385 5 of 18
(4) duplicates [17], (5) without author of identification, and (6) outside the ellipse at
99% of a PCA conducted with the package ‘FactoMiner’ [36], using 15 environmental
variables and altitude. Spatial autocorrelation between records was then eliminated with
the package ‘spThin’ [41], allowing a single record per pixel (∼5 km). If we did not correct
for this characteristic, we would have incurred in a biased selection of variables or model
coefficients [42].
2.4. Calibration Area
Areas where the species could be observed or that could be explored because of their
biological capacity are denoted as «M» in the «BAM» diagram [29]. This was delimited
preliminarily in ArcMap v.10.5, applying a 70 km buffer radius to each species occurrence
records. In SDM and ENM, the calibration areas should include the complete distribution of
the species [20]. If the extension of this area is smaller than the species range, the response
function cannot have the predicted form, because of the niche theory [22]. The final
delimitation of «M» was achieved with the cleansed records, that is, with those that passed
all the cleaning criteria indicated in the previous section.
2.5. Model Calibration, Creation, and Evaluation
The model calibration, creation, and evaluation were done in ‘kuenm’, an R package
that uses Maxent (maximum entropy) [43] as the modeling algorithm. Maxent has two
main modifiable parameters: (1) “regularization multiplier” (β) and (2) “feature classes”
such as linear (l), quadratic (q), product (p), threshold (t) and hinge (h). The first is a
parameter that adds new constraints; it is a penalty imposed on the model, and the latter
corresponds to a mathematical transformation of the different covariates used in the model
to allow complex relationships to be modeled [37,44]. For each species, 16 regularization
multiplicators were tested (0.1 to 1, 2 to 6, and 10), 29 response types (l, q, p, t, h, lq, lp, lt,
lh, qp, qt, qh, pt, ph, th, lqp, lqt, lqh, lpt, lph, qpt, qph, qth, qth, lqpt, lqph, lqth, lpth and
lqpth), and three different sets of environmental variables (optional), those that satisfied
the selection criteria indicated in Section 2.2.
Modeling was carried out with approximately 70% of the records; with independent
data (∼30%), the predictive capacity of the models was evaluated using cross validation [36].
This percentage depends on the availability of independent records of each species used for
validation. The output format was of logistical type, which can be interpreted as probability
of presence and is recommended if and only if the “regularization multiplier” and “feature
classes” [45] are optimized. The resulting models (maps in raster format) represent species
suitability values (0–1) [46].
The best fit model was selected according to: (1) the statistic partial ROC (Receptor
Operated Curve) [47], (2) the rate of omission 0.05%, (3) the lowest value of the Akaike
Information Criterion (AICc) [19,48,49], (4) species response curves to the environmental
gradients [37], and (5) statistical significance of the model, p-values [19]. Here, the partial
ROC was used instead of the area under the ROC curve (AUC) because the latter is not a
good measure of fit in ENM [47,50]. Statistical significance was determined by a bootstrap
resampling of 50% of testing data.
To reduce bias, the final selected model was represented by the mean of 10 repetitions,
with which prediction uncertainty was obtained. The jackknife tests and the response
curves to bioclimatic variables were implemented in ‘kuenm’ [43] to determine the vari-
able’s contribution to the model. The process for generating the climate suitability model
of the species is shown in Figure 2.
6. Forests 2021, 12, 385 6 of 18
Forests 2021, 12, x FOR PEER REVIEW 6 of 19
Figure 2. General scheme of steps and procedures for ecological niche model generation.
2.6. Model Stratification
The final continuous model of probability (suitability) of each species was classi-
fied in three levels or strata: low, medium and high suitability. To this end, 5000 points
were distributed randomly over the suitability model; from these points their value
was extracted. Later, in R with the package ‘stratifyR’ [51], the thresholds of each stra-
tum were calculated following the method of Khan et al. (2002) [52], Khan et al. (2008)
[53] and Khan et al. (2015) [54]. This method determines the Optimum Strata Bounda-
ries (OSB) and Optimum Sample Sizes (OSS) for the study variable, using the best-fit
frequency distribution of a survey variable. It formulates the problem of determining
the OSB as a mathematical programming problem, which is solved using a dynamic
programming technique, using Neyman Allocation assuring minimum intra-stratum
variance and maximum inter-stratum variance.
2.7. Bark Beetle-Free Areas
The final suitability models of each species were converted into binary maps in
ArcMap v.10.5 to represent climate suitability-non-suitability. This was done by reclas-
sifying the suitability to 1 and 0; the value of one (1) was assigned to suitability com-
prehended between the minimum value of the second stratum (calculated in the pre-
Figure 2. General scheme of steps and procedures for ecological niche model generation.
2.6. Model Stratification
The final continuous model of probability (suitability) of each species was classified
in three levels or strata: low, medium and high suitability. To this end, 5000 points were
distributed randomly over the suitability model; from these points their value was ex-
tracted. Later, in R with the package ‘stratifyR’ [51], the thresholds of each stratum were
calculated following the method of Khan et al. (2002) [52], Khan et al. (2008) [53] and
Khan et al. (2015) [54]. This method determines the Optimum Strata Boundaries (OSB)
and Optimum Sample Sizes (OSS) for the study variable, using the best-fit frequency
distribution of a survey variable. It formulates the problem of determining the OSB as a
mathematical programming problem, which is solved using a dynamic programming tech-
nique, using Neyman Allocation assuring minimum intra-stratum variance and maximum
inter-stratum variance.
2.7. Bark Beetle-Free Areas
The final suitability models of each species were converted into binary maps in Ar-
cMap v.10.5 to represent climate suitability-non-suitability. This was done by reclassifying
the suitability to 1 and 0; the value of one (1) was assigned to suitability comprehended
between the minimum value of the second stratum (calculated in the previous section)
7. Forests 2021, 12, 385 7 of 18
and that of maximum suitability, while the value of zero (0) corresponded to the rest
of the suitability. The binary maps were manipulated using ‘raster algebra’ of each pair
of species (Pinus–D. mexicanus), and SAP free of SAD were calculated. The procedures
based on spatial predictions of climate suitability (also called ENMs), besides estimating
SAP–SAD [49], allow quantifying changes and niche overlap of two or more species in G
space [20].
2.8. Quantifying Niche Similarity
Similarity between the Dendroctonus and Pinus niches was calculated with two indexes
introduced by Warren et al. (2008) [31]: Schoener’s (1968) [55] D and a measure derived
from Hellinger’s distance called I using ordination methods (PCA) and the 15 bioclimatic
variables for each species [20] (Table 1). This method is the most precise [56] and the most
recommended [20,57]. Both similarity measures range from 0, when species predicted envi-
ronmental tolerances do not overlap at all, to 1, when overlap is total. Niche comparisons
were made relative to the entire niche of the species, pooled from the two ranges [20,31],
under the hypothesis of niche conservatism of the genus Pinus; it is known that it was
established ∼145 million years ago in the lower Cretaceous [58], and the bark beetle as an
invasive species. A kernel density function (standard smoothing parameters) was applied
to determine the ‘smoothed’ density of occurrences in each cell in the environmental space
for each dataset; the use of a kernel smoother makes the process of moving from G space to
multivariate E space, independent of both sampling and resolution in environmental space.
The shift of the middle position from centroid of the niche between the species of bark
beetle with the pine species was calculated with the C metric, using Euclidian distance [20].
This analysis was performed with the package ‘ecospat’ [59]. All the packages mentioned
in this study were run in R 3.6.3 [60].
3. Results
3.1. Generalities
A total of 283, 3648, 2209 and 772 species occurrence records were collected for
D. mexicanus, P. leiophylla, P. teocote and P. devoniana, subtracting for the modeling and
validation 86, 900, 736 and 255 (30.39, 24.67, 33.32 and 33.03%); that is, up to 75.33% of the
P. leiophylla records were eliminated, because they did not meet the established cleaning
criteria (Section 2.3).
The PCA performed to select the variables by their contribution, explained 67.63,
73.48, 65.60 and 64.10% for the different species (Table 1). This analysis is statistically valid
when the variables correlate with each other (0.6). The Kaiser–Meyer–Olkin (KMO) index
indicated that the global correlation of the PCA was 0.68, 0.71, 0.72, and 0.65, respectively.
The results show that in the four species, the variables derived from temperature (Bio 1–Bio
11) are those that most contributed; variable 16 (Precipitation of Wettest Quarter, mm) is
that which least contributed (Table 1). There are variables (e.g., Bio 12 and Bio 13, for the
species D. mexicanus) that contribute significantly in the PCA (Table 1). However, they
were not selected because they presented a bimodal distribution.
3.2. Generated Models and Their Statistics
A total of 1392 candidate models were generated for each species (Table 2). It is
notable that not all the models were statistically significant (α = 0.05), registering 99.4%
for D. mexicanus, 53.5% for P. leiophylla, 99.9% for P. teocote and only 9.5% for P. devoniana
(Table 2), using the default parameters in Maxent does not necessarily produce the best
model [61] (see Appendix A). The type of response that prevailed in the selected models
was quadratic (Table 2). No linear response model was selected in any case. The algorithm
implemented in ‘kuenm’ [43] selected the best regulating multiplier in each species varied
from 2 (D. mexicanus and P. devoniana) to 5 (P. leiophylla).
8. Forests 2021, 12, 385 8 of 18
Table 2. Candidate models generated and selected, and their fit and validation statistics.
Criterion/Species D. mexicanus P. leiophylla P. teocote P. devoniana
Calibration and evaluation of candidate models
TCM 1392 1392 1392 1392
SSM 1383 745 1328 132
MCOr 262 0 763 201
MAIC 1 3 1 2
n of SSM and MCOr 254 0 763 201
n of SSM and MAIC 1 3 1 2
n of SSM, MCOr and MAIC 1 0 1 1
Selected model M_2_F_t (2) M_5_q (3) M_3_F_qth (1) M_2_F_qh (1)
Statistics of the selected model
Mean AUC ratio 1.66 1.24 1.49 1.35
Rate of omission 0.05% 0.05 0.77 0.04 0.03
AICc 1683.34 17393.42 13851.28 4900.27
delta AICc 21.6 252.84 251.35 61.26
TCM = total candidate models; SSM = statistically significant models; MCOr = models that satisfy the criterion of omission rate,
MAIC = models that satisfy the AICc; AICc = Aikaike information criterion, (1,2,3) = set number.
Fewer than 20% of the 1392 models generated passed the omission rate (false negative
predictions) established (0.05%); indeed, none satisfied in the species P. leiophylla, having
to increase the established value to 0.07% to select the model. Only one model (0.07% of
the total) passed all the criteria established in Section 2.5 (Table 2) in D. mexicanus and
P. devoniana.
3.3. Species Suitability Areas
In no case did climate suitability reach the maximum value (1), varying from 0.01 (P. teocote)
to 0.82 (P. leiophylla). Suitability takes on different forms, triangular in D. mexicanus and
P. devoniana with parameters a = 0.001 and 0.001; b = 0.732 and 0.795; c = 0.518 and 0.01,
respectively. Gamma distribution in P. leiophylla and P. teocote had values of k = 0.702 and
0.526; λ = 3.082 and 3.728, respectively. The OSBs varied in each species and not in the same
amplitude, showing that variance differs in all the spectrum of species climate suitability.
For this reason, stratification should obey a statistical technique rather than stratify by
proportions, assuring minimum and maximum intra-stratum variance among them.
It is estimated that the area of high suitability in Mexico is 234,649.1, 212,497.4,
177,904.8 and 159,630.4 km2 for D. mexicanus, P. leiophylla, P. teocote and P. devoniana
(Figure 3a–d). Except for P. teocote (Figure 3c), high suitability represents that largest part of
«M», from 39.89% (P. devoniana, Figure 3d) to 47.85% (P. leiophylla, Figure 3b). The predicted
area of suitability for a species is not dependent on the number of registers. Maxent uses
presence records to model climate suitability. During this process, the algorithm generates
“pseudo absences” where the species is not present. This helps to improve the predictions
of the current distribution of the species.
3.4. Bioclimatic Profile
The ‘kuenm’ algorithm selected the set of variables (Table 3) that showed the best
predictive capacity, validated with the set of independent records of the species. The sets
comprised different numbers of variables, from three (P. leiophylla) to seven (P. teocote).
Like the PCA, the jackknife tests showed that the variables derived from temperature
(Bio 1–Bio 11) contribute more than 80% to explain the bioclimatic profile of the species
(Table 3), especially, the representatives of extreme values. In D. mexicanus and P. leiophylla
a single variable contributes significantly to the species bioclimatic profile, 87.8% (Bio 10)
and 93.9% (Bio 1), respectively. The average coefficient of variation of the variables that
most contribute to the bioclimatic profile of each species (Bio 10, Bio 1, Bio 10 and Bio
11, Table 3) is 14.3%, indicating that the predictors selected by both PCA (preselection of
9. Forests 2021, 12, 385 9 of 18
variables) and the ‘kuenm’ algorithm adequately represent the species bioclimatic profile.
Only one variable (Bio 6, in P. teocote) experienced high variability (198.9%) but contributes
to the bioclimatic profile with only 15.6% (Table 3).
Forests 2021, 12, x FOR PEER REVIEW 9 of 19
Figure 3. Climate suitability for: (a) Dendroctonus mexicanus, (b) Pinus leiophylla, (c) Pinus teo-
cote, and (d) Pinus devoniana, stratified in medium, high and low, according to the minimum
and maximum intra-stratum variance among them, solved by using a dynamic programming
technique.
3.4. Bioclimatic Profile
The ‘kuenm’ algorithm selected the set of variables (Table 3) that showed the best
predictive capacity, validated with the set of independent records of the species. The
sets comprised different numbers of variables, from three (P. leiophylla) to seven (P.
teocote). Like the PCA, the jackknife tests showed that the variables derived from tem-
perature (Bio 1–Bio 11) contribute more than 80% to explain the bioclimatic profile of
the species (Table 3), especially, the representatives of extreme values. In D. mexicanus
and P. leiophylla a single variable contributes significantly to the species bioclimatic
profile, 87.8% (Bio 10) and 93.9% (Bio 1), respectively. The average coefficient of varia-
tion of the variables that most contribute to the bioclimatic profile of each species (Bio
10, Bio 1, Bio 10 and Bio 11, Table 3) is 14.3%, indicating that the predictors selected by
both PCA (preselection of variables) and the ‘kuenm’ algorithm adequately represent
the species bioclimatic profile. Only one variable (Bio 6, in P. teocote) experienced high
variability (198.9%) but contributes to the bioclimatic profile with only 15.6% (Table 3).
Table 3. Relative contribution (in percentage) of the suitability model bioclimatic variables of each species determined
by the jackknife test and the detailed bioclimatic profile of the species.
Variable Contrib. Dendroctonus mexicanus
Name (%) Length Mean MeanCI 0.05 0.10 0.25 Median 0.75 0.90 0.95 Range SD CV MAD IQR
Bio 6 4.7 86 53.0 ±7.0 −10.1 6.7 34.0 55.2 74.3 95.6 100.6 153.8 32.5 61.3 31.4 40.3
Bio 10 87.8 86 180.7 ±5.6 140.5 149.6 166.3 178.7 201.3 218.5 221.2 130.7 26.1 14.4 28.1 35.0
Bio 15 3.2 86 89.2 ±2.7 65.9 71.8 79.8 90.7 100.2 103.4 106.4 52.6 12.6 14.1 14.3 20.4
Bio 16 4.3 86 578.2 ±43.7 307.8 325.0 430.5 546.0 708.8 877.0 962.0 834.0 204.0 35.3 201.6 278.3
Pinus leiophylla
Bio 1 93.9 900 138.7 ±1.2 111.9 116.1 126.5 136.4 149.5 164.1 171.4 99.0 17.9 12.9 17.1 23.0
Bio 2 5.6 900 118.9 ±0.7 95.1 103.1 116.8 123.0 125.7 128.1 129.0 62.3 11.0 9.3 4.9 9.0
Bio 7 0.5 900 246.6 ±2.8 169.3 181.2 219.9 253.9 277.4 297.1 305.8 202.2 42.1 17.1 40.5 57.5
Pinus teocote
Bio 4 3.8 735 3363.6 ±79.6 1195.5 1553.3 2962.3 3628.8 3956.4 4698.7 4916.2 533.6 1098.5 32.7 600.7 994.1
Bio 6 15.6 735 18.4 ±2.7 -19.5 -14.6 -6.4 3.5 37.0 78.1 93.9 195.5 36.6 198.9 20.1 43.4
Bio 7 3.3 735 227.9 ±2.8 156.2 164.3 212.2 238.3 251.5 269.1 275.3 200.0 38.0 16.7 23.1 39.3
(a) (b)
(c) (d)
Figure 3. Climate suitability for: (a) Dendroctonus mexicanus, (b) Pinus leiophylla, (c) Pinus teocote,
and (d) Pinus devoniana, stratified in medium, high and low, according to the minimum and maximum
intra-stratum variance among them, solved by using a dynamic programming technique.
Table 3. Relative contribution (in percentage) of the suitability model bioclimatic variables of each species determined by
the jackknife test and the detailed bioclimatic profile of the species.
Variable Contrib. Dendroctonus mexicanus
Name (%) Length Mean MeanCI 0.05 0.10 0.25 Median 0.75 0.90 0.95 Range SD CV MAD IQR
Bio 6 4.7 86 53.0 ±7.0 −10.1 6.7 34.0 55.2 74.3 95.6 100.6 153.8 32.5 61.3 31.4 40.3
Bio 10 87.8 86 180.7 ±5.6 140.5 149.6 166.3 178.7 201.3 218.5 221.2 130.7 26.1 14.4 28.1 35.0
Bio 15 3.2 86 89.2 ±2.7 65.9 71.8 79.8 90.7 100.2 103.4 106.4 52.6 12.6 14.1 14.3 20.4
Bio 16 4.3 86 578.2 ±43.7 307.8 325.0 430.5 546.0 708.8 877.0 962.0 834.0 204.0 35.3 201.6 278.3
Pinus leiophylla
Bio 1 93.9 900 138.7 ±1.2 111.9 116.1 126.5 136.4 149.5 164.1 171.4 99.0 17.9 12.9 17.1 23.0
Bio 2 5.6 900 118.9 ±0.7 95.1 103.1 116.8 123.0 125.7 128.1 129.0 62.3 11.0 9.3 4.9 9.0
Bio 7 0.5 900 246.6 ±2.8 169.3 181.2 219.9 253.9 277.4 297.1 305.8 202.2 42.1 17.1 40.5 57.5
Pinus teocote
Bio 4 3.8 735 3363.6 ±79.6 1195.5 1553.3 2962.3 3628.8 3956.4 4698.7 4916.2 533.6 1098.5 32.7 600.7 994.1
Bio 6 15.6 735 18.4 ±2.7 -19.5 -14.6 -6.4 3.5 37.0 78.1 93.9 195.5 36.6 198.9 20.1 43.4
Bio 7 3.3 735 227.9 ±2.8 156.2 164.3 212.2 238.3 251.5 269.1 275.3 200.0 38.0 16.7 23.1 39.3
Bio 10 63.8 735 178.5 ±1.3 152.6 158.2 166.7 176.0 187.9 201.9 210.9 150.3 18.5 10.4 14.9 21.1
Bio 11 5 735 87.6 ±2.3 51.8 57.3 66.1 76.9 102.8 138.5 153.6 183.4 31.8 36.3 20.6 36.6
Bio 12 6.5 735 901.0 ±18.0 581.7 626.0 723.0 847.0 1045.5 1250.6 1392.9 1424.0 248.5 27.6 225.4 322.5
Bio 15 2.1 735 92.1 ±0.9 71.4 76.5 83.9 92.9 101.1 106.5 110.3 76.0 11.8 12.8 12.9 17.2
Pinus devoniana
Bio 4 28.2 255 1813.2 ±61.3 1072.3 1165.8 1523.7 1780.2 1985.4 2440.0 2745.9 2892.5 497.3 27.4 338.6 461.7
Bio 7 1.3 255 181.9 ±3.2 132.0 139.0 162.7 189.6 199.1 212.2 218.3 115.3 26.1 14.3 23.4 36.4
Bio 11 50.8 255 141.9 ±3.5 99.8 107.2 119.3 139.7 162.0 176.8 188.3 140.5 27.5 19.4 31.7 42.7
Bio 12 19.8 255 1090.0 ±40.5 608.8 712.4 858.5 1043.0 1265.5 1579.4 1770.8 1624.0 328.7 30.2 309.9 407.0
MeanCI = confidence interval of mean, 0.05, 0.95 = quantiles of the bioclimatic variable, SD = standard deviation, CV = coefficient of
variation (%); MAD = median absolute deviation, IQR = interquartile range.
10. Forests 2021, 12, 385 10 of 18
3.5. Climatic Suitability of Pine Species, Free of Bark Beetle Suitability Areas
From the total suitable area predicted for P. leiophylla (444,100.4 km2), P. teocote
(729,358.3 km2), and P. devoniana (400,142.8 km2) (Figure 3b–d) and by obtaining SAP–free
of SAD of each Pinus–Dendroctonus pair (Section 2.7), we found that only 92,995.2, 11,737.4
and 55,964.8 km2, respectively, are free of suitable bark beetle areas. For P. teocote, of the
total of the suitable areas, only 3.02% is left.
Despite the wide distribution of P. leiophylla and P. teocote (Figure 3b–c), SAP–free
of SAD are observed only in a northern part of the SMOc (Figure 4a,b), where there is
a larger number (seven) of bark beetle species [13], in a compact form for the first pine
species P. leiophylla and disperse for the second P. teocote, but inexistent in lower latitudes
of the species distribution. In P. devoniana (Figure 4c), the SAP–free of SAD are observed
discontinuously over the entire area of its distribution. In all cases, these areas are observed
where there is high climatic suitability for the pine species and the bark beetle. Chihuahua
and Sonora have 81.56% of the total SAD–free P. leiophylla suitable areas. Chihuahua and
Durango contain 57.60% of the SAD–free P. teocote suitable areas, while Jalisco contributes
30.39% of the SAD–free P. devoniana suitable areas. It is possible that, in the future, these
areas (SAP–free of SAD) may be susceptible to the bark beetle.
Bio 11 50.8 255 141.9 ±3.5 99.8 107.2 119.3 139.7 162.0 176.8 188.3 140.5 27.5 19.4 31.7 42.7
Bio 12 19.8 255 1090.0 ±40.5 608.8 712.4 858.5 1043.0 1265.5 1579.4 1770.8 1624.0 328.7 30.2 309.9 407.0
MeanCI = confidence interval of mean, 0.05, 0.95 = quantiles of the bioclimatic variable, SD = standard deviation, CV =
coefficient of variation (%); MAD = median absolute deviation, IQR = interquartile range.
3.5. Climatic Suitability of Pine Species, Free of Bark Beetle Suitability Areas
From the total suitable area predicted for P. leiophylla (444,100.4 km2), P. teocote
(729,358.3 km2), and P. devoniana (400,142.8 km2) (Figure 3b–d) and by obtaining SAP–
free of SAD of each Pinus–Dendroctonus pair (Section 2.7), we found that only 92,995.2,
11,737.4 and 55,964.8 km2, respectively, are free of suitable bark beetle areas. For P.
teocote, of the total of the suitable areas, only 3.02% is left.
Despite the wide distribution of P. leiophylla and P. teocote (Figure 3b–c), SAP–free
of SAD are observed only in a northern part of the SMOc (Figure 4a,b), where there is
a larger number (seven) of bark beetle species [13], in a compact form for the first pine
species P. leiophylla and disperse for the second P. teocote, but inexistent in lower lati-
tudes of the species distribution. In P. devoniana (Figure 4c), the SAP–free of SAD are
observed discontinuously over the entire area of its distribution. In all cases, these ar-
eas are observed where there is high climatic suitability for the pine species and the
bark beetle. Chihuahua and Sonora have 81.56% of the total SAD–free P. leiophylla suit-
able areas. Chihuahua and Durango contain 57.60% of the SAD–free P. teocote suitable
areas, while Jalisco contributes 30.39% of the SAD–free P. devoniana suitable areas. It is
possible that, in the future, these areas (SAP–free of SAD) may be susceptible to the
bark beetle.
According to our results, uncertainty is not more than 30% of the coefficient of
variation (Figure 4d–f). The lowest uncertainty (0.15%) occurs in the areas of high
suitability and the highest (97%) in areas of low suitability.
(a) (d)
Forests 2021, 12, x FOR PEER REVIEW 11 of 19
(b) (e)
(c) (f)
Figure 4. Suitable areas free of the bark beetle for: (a) Pinus leiophylla (orange color), (b) Pinus teocote (blue color), and
(c) Pinus devoniana (green color), suitable areas free of the bark beetle Dendroctonus mexicanus. Average uncertainty,
expressed as variation coefficient of the prediction model of each pine species (d–f), respectively. The continuous line
is the bark beetle calibration area; dotted line and shaded area is the pine species calibration area.
3.6. Overlap of Suitability and Ecological Niches
The overlap of suitable areas of the bark beetle with those of P. leiophylla, P. teocote
and P. devoniana in space G is 74.35, 96.98 and 82.44%, respectively (Figure 5a–c). The
environmental space (Figure 5d–f) was built with Bio 5, Bio 6, and Bio 12 for the pur-
Figure 4. Suitable areas free of the bark beetle for: (a) Pinus leiophylla (orange color), (b) Pinus teocote (blue color), and (c)
Pinus devoniana (green color), suitable areas free of the bark beetle Dendroctonus mexicanus. Average uncertainty, expressed
as variation coefficient of the prediction model of each pine species (d–f), respectively. The continuous line is the bark beetle
calibration area; dotted line and shaded area is the pine species calibration area.
11. Forests 2021, 12, 385 11 of 18
According to our results, uncertainty is not more than 30% of the coefficient of variation
(Figure 4d–f). The lowest uncertainty (0.15%) occurs in the areas of high suitability and
the highest (97%) in areas of low suitability.
3.6. Overlap of Suitability and Ecological Niches
The overlap of suitable areas of the bark beetle with those of P. leiophylla, P. teocote
and P. devoniana in space G is 74.35, 96.98 and 82.44%, respectively (Figure 5a–c). The en-
vironmental space (Figure 5d–f) was built with Bio 5, Bio 6, and Bio 12 for the purpose
of comparing the fundamental niche and overlap between bark beetle and pine species.
In Bio 5 (maximum temperature), the four species have the same tolerances, from 1 to 32 ◦C
(Figure 5d–f); in Bio 6 (minimum temperature) the overlap is -2 to 11 ◦C, but D. mexicanus
has broader tolerance (from −1 to 17 ◦C). The lowest occurs in P. leiophylla (from −4 to
11 ◦C). In Bio 12 (annual precipitation), the overlap occurs between 450 and 1755 mm. P.
devoniana, the species of limited distribution, possesses the widest interval, from 429 to
2053 mm (Figure 4f); D. mexicanus tolerates a smaller interval (450 to 1755 mm). The fun-
damental niche of the pine species shows the same disposition in tridimensional space,
but different from that of bark beetle species (Figure 5d–f), but in all niches unavailable
climate (UC) and the existence of a potential niche (PN) are observed (Figure 5d–f).
Forests 2021, 12, x FOR PEER REVIEW 12 of 19
Figure 5. Overlap of climate suitability of Dendroctonus mexicanus with Pinus leiophylla. (a), Pinus
teocote (b) and Pinus devoniana (c) in the geographic space. Overlap of niches in the environmental
space of this same species association (d–f), composed of three bioclimatic dimensions (Bio 5:
Max Temperature of Warmest Month in °C ×10), Bio 6: Min Temperature of Coldest Month in
°C ×10 and Bio 12: Annual Precipitation in mm). Each blue dot corresponds to the environmental
combination represented in one of 50,000 grid cells at 5 × 5 km of spatial resolution, unavailable
climate (UC) and potential niche (PN).
Niche similarity between the ‘invasive’ species (D. mexicanus) and the pine species
resulted in D = 0.48 and I = 0.67; D = 0.39 and I = 0.61; D = 0.53 and I = 0.69, for P.
leiophylla (Figure 6a), P. teocote (Figure 6b) and P. devoniana (Figure 6c). The variance
explained by the first two principal components was 61.76% (P. devoniana) to 71.73%
(P. leiophylla). In all cases, the variables derived from temperature contributed more in
the PCA (PC1) and those of precipitation (PC2) contributed less (Figure 6d–f).
(d)
(e)
(f)
UC
(a)
(b)
(c)
PN
UC PN
UC
PN
Figure 5. Overlap of climate suitability of Dendroctonus mexicanus with Pinus leiophylla. (a), Pinus teocote (b) and Pinus
devoniana (c) in the geographic space. Overlap of niches in the environmental space of this same species association (d–f),
composed of three bioclimatic dimensions (Bio 5: Max Temperature of Warmest Month in ◦C ×10), Bio 6: Min Temperature
of Coldest Month in ◦C ×10 and Bio 12: Annual Precipitation in mm). Each blue dot corresponds to the environmental
combination represented in one of 50,000 grid cells at 5 × 5 km of spatial resolution, unavailable climate (UC) and potential
niche (PN).
12. Forests 2021, 12, 385 12 of 18
Niche similarity between the ‘invasive’ species (D. mexicanus) and the pine species
resulted in D = 0.48 and I = 0.67; D = 0.39 and I = 0.61; D = 0.53 and I = 0.69, for P. leiophylla
(Figure 6a), P. teocote (Figure 6b) and P. devoniana (Figure 6c). The variance explained by the
first two principal components was 61.76% (P. devoniana) to 71.73% (P. leiophylla). In all
cases, the variables derived from temperature contributed more in the PCA (PC1) and
those of precipitation (PC2) contributed less (Figure 6d–f).
Forests 2021, 12, x FOR PEER REVIEW 13 of 19
99.15, and 95.37%, respectively. The shift from niche centroid (C) of the ‘invasive’ spe-
cies was more significant with P. leiophylla and P. teocote (Figure 6a–b), but in different
directions, and almost the same centroid as observed with P. devoniana (Figure 6c). In
the three cases, the shift moved over the temperature gradient. Under the similarity
hypothesis of ecological niches of the species in niche conservatism (Pinus) and ‘inva-
sive’ species (Dendroctonus), it is observed that both measures of niche similarity are
significantly higher than what was expected of this null distribution, with p 0.05 (Fig-
ure 6g–i). Therefore, this hypothesis is rejected, except in the case of D. mexicanus with
P. devoniana (Figure 6g–i) where p 0.05.
Figure 6. Niche of the species along the two first axes of the PCA (a–c) of the native species and ‘invasive’ species.
Green (Pinus) and blue (Dendroctonus mexicanus) (D), shading shows the density of the occurrences of the species by
cell. The solid and dashed contour lines illustrate, respectively, 100% and 95% of the available (background) environ-
ment, E represents niche expansion and Up the non-overlapping niche between pine species and the ‘invasive’ species.
The arrows represent the change of the niche centroid of the ‘invasive’ species, relative to the ‘native’ species. The
contribution of the climatic variables on the two axes of the PCA and the percentage of inertia explained by the two
axes (d–f). Histograms show the observed niche similarity I between the two ranges (lines with a diamond) and simu-
lated niche similarity (grey bars). Pinus leiophylla (a,d,g), Pinus teocote (b,e,h) and Pinus devoniana (c,f,i).
Figure 6. Niche of the species along the two first axes of the PCA (a–c) of the native species and ‘invasive’ species. Green
(Pinus) and blue (Dendroctonus mexicanus) (D), shading shows the density of the occurrences of the species by cell. The solid
and dashed contour lines illustrate, respectively, 100% and 95% of the available (background) environment, E represents
niche expansion and Up the non-overlapping niche between pine species and the ‘invasive’ species. The arrows represent
the change of the niche centroid of the ‘invasive’ species, relative to the ‘native’ species. The contribution of the climatic
variables on the two axes of the PCA and the percentage of inertia explained by the two axes (d–f). Histograms show the
observed niche similarity I between the two ranges (lines with a diamond) and simulated niche similarity (grey bars). Pinus
leiophylla (a,d,g), Pinus teocote (b,e,h) and Pinus devoniana (c,f,i).
The proportion of the native niche (P. leiophylla, P. teocote and P. devoniana) non–
overlapping with the ‘invasive’ niche (D. mexicanus), denoted as Up (Unfilling) is 31.57,
19.44, and 21.15%; niche expansion E is 1.31, 0.84, and 4.62, while niche stability is 98.68,
99.15, and 95.37%, respectively. The shift from niche centroid (C) of the ‘invasive’ species
was more significant with P. leiophylla and P. teocote (Figure 6a–b), but in different directions,
and almost the same centroid as observed with P. devoniana (Figure 6c). In the three
13. Forests 2021, 12, 385 13 of 18
cases, the shift moved over the temperature gradient. Under the similarity hypothesis
of ecological niches of the species in niche conservatism (Pinus) and ‘invasive’ species
(Dendroctonus), it is observed that both measures of niche similarity are significantly higher
than what was expected of this null distribution, with p 0.05 (Figure 6g–i). Therefore, this
hypothesis is rejected, except in the case of D. mexicanus with P. devoniana (Figure 6g–i)
where p 0.05.
4. Discussion
4.1. Species Occurrence Records in ENM
The used of reliable records is fundamental in ENM to avoid bias in prediction, mainly
because the primary source of data is an opportunist sampling [22]. In general, 70% of the
records were eliminated. The use of altitudinal limits of species distribution in records
cleansing has not been documented. Here, it can be observed that altitude (included in
the PCA with the Bios) was crucial to identifying atypical and erroneous records of the
species, especially within «M». Much has been discussed over the number of species
occurrence records to use in ENM; some show that 30 should be a minimum [25], while
others indicate that 50 is sufficient [62]. Modeling D. mexicanus in this study was carried out
with 86 records. Modeling the pine species surpassed 250 records. Actually, the number of
observations is less important than adequately representing species prevalence distributed
in the entire geographic and environmental space it occupies [22], for which it is of utmost
importance that in SDM and ENM the records comprehend the complete distribution of the
species (as was done here). Otherwise, the response of the variables would be wrong [20],
as would be the ecological niche. It has been demonstrated that systematic sampling
produces greater precision in species distribution models [22]. Some records used here
(INFyS) come from this type of sampling, assuring more robust predictions. Moreover, this
requirement was corrected by removing spatial autocorrelation.
4.2. Variable Importance in ENM
After Busby (1986) [26] defined bioclimatic variables from precipitation and tempera-
ture, a number of different predictors have been generated, but used indistinctly in ENM,
despite the fact that some authors [22,29,32] have suggested their use depending on the
study scale. Modeling the species of this study was carried out only with bioclimatic
variables, [22,29,32]. The rigorous selection of predictors and the best configuration of
the algorithm made it possible to choose a robust model to predict the climatic suitability
of each species. Other researchers [19] demonstrated that if this process is appropriate
the model will show minimum spatial correlation in their residuals. The use of dynamic
(bioclimatic) variables for modeling allows determining the vulnerability of a species, in an
unstable environment which does not occur with static variables (soil, slope, exposure
and altitude) [63]. In 2017, Fourcade and other researchers surprised the scientific com-
munity when they demonstrated that pseudo–predictors derived from paints (‘classical
paintings’) downloaded from Google Image®, predicted species distribution even better
than bioclimatic variables. Undoubtedly, such pseudo–predictors will not satisfy the crite-
ria established in this study (Section 2.2), and so it is crucial to select the environmental
predictors in ENM. To generate our models, besides considering these criteria, the ‘kuenm’
algorithm selected the best set of variables based on the validation of 1392 candidate
models, using the set of independent records.
It has been demonstrated that using multiple variables brings problems of bias and
uncertainty in the predictions [38,42] and a decrease in statistical power; complex models
with a large number of parameters tend to overestimate the predictions [38,64] but this
depends on the combination of the adjustment parameters of the “regularization multiplier”
and “feature classes” [43]. However, this occur especially when the number of records
is small [38,64]. Our models included no more than seven predictors avoiding these
problems. Other authors argue that a large number of predictors resulted in problems
of collinearity [25,35,38], which tend to inflate the variance of response variables and
14. Forests 2021, 12, 385 14 of 18
parameters [42], and an erroneous representation of species distribution [16,40], moreover,
biological interpretation of the model is complex or null.
Austin (2002) [65] argues that species responses are often nonlinear; likewise, ecologi-
cal theory suggests response curves are often unimodal [66], and hence, quadratic features
may be appropriate. None of our generated models for the studied species was linear;
most were quadratic (Table 2), in accord with theory these authors, which demonstrates
the correct selection of predictors, quality of records and modeling. Studies reveal that
pine species show non–linear responses to climate suitability [67], like what occurs in bark
beetle species [18].
Our findings indicate that regardless of the genus and species, the variables of tem-
perature are those that most contributed to the bioclimatic profile, especially seasonal
temperature means and extremes (e.g., Bio 10 and Bio 11, Table 3), as occurs in most
studies of ENM [67–69], even when topographic [28], soil and vegetation [67] variables are
included in modeling. For bark beetles, the variables that best predict climatic suitability
are temperature [12,70]; e.g., Bio 1 in Dendroctonus rizophagus Thomas Bright [35]; Bio 5 in
Dendroctonus valens Le Conte [71] and Bio 10 in D. mexicanus [18], and in this last species
Bio 7, Bio 8, and Bio 10 [28]. It has been found that D. mexicanus possesses a more ample
bioclimatic profile than that of several other bark beetle species [18], making it possible to
occupy larger geographic areas and probably adapt to new host pine species.
It is surprising that a single variable, e.g., Bio 1 in P. leiophylla and Bio 10 in D. mexi-
canus, contributes more than 90 and 87%, respectively (Table 3). Like what we found here,
it has been demonstrated [71,72] that a single variable predicts plant species distribution
very well. In contrast, other authors [23] report models of up to 38 predictors. The number
of variables that make up a model (as long as they have been correctly selected) possess a
fundamental interpretation. Our analysis shows that this could determine species vulnera-
bility. When the contribution of a single variable is high, there is a risk that if it changes
(increases/decreases) and varies over time, it will have important effects on predictions of
climate suitability, making the species vulnerable in the same proportions. In contrast, if the
model is composed of multiple variables, their contribution would be shared, increasing
the possibility that not all are being modified at the same rhythm, even if they do not.
Specifically, in the study area, Bio 1 has increased significantly in recent years [7],
a fact that we have verified through climate projections of the GCM’s [33], with an expected
increase of 2 to 3.5 ◦C by the year 2050, making P. leiophylla and D. mexicanus highly
vulnerable to climate change. The latter is even more vulnerable because of its high
dependence and sensitivity to temperature [10], while P. teocote and P. devoniana are less
vulnerable. Previous studies on ecological niche models [42] demonstrate that P. leiophylla
is highly vulnerable to climate change, as found here.
4.3. Climate Suitability and Niche Overlap
The stratification of species climate suitability can determine priority areas for con-
servation or management, especially those of high suitability. The areas of low suitability
represent areas that in the past were of medium of high suitability, but nothing can be done
to remedy this condition. Low suitability for D. mexicanus (Figure 3a) and P. devoniana
(Figure 3d) is observed only at higher latitudes and almost never at lower latitudes, chal-
lenging distributional ecology where maximum suitability of the species occurs toward
the center of spaces E and G [24]. Analogously, it has been found [13] that greater suitabil-
ity of D. mexicanus is registered in small portions of the TMVB and the SMOc at higher
altitudes and where Pinus–Dendroctonus host diversity is high but discontinuous [14,49].
For Pinus, suitability also occurs at higher altitudes [42], possibly following regimes of
higher moisture and lower temperatures.
Superimposing climate suitability (Dendroctonus–Pinus) resulted in very few discon-
tinuous SAP free of SAD (between 30.03 and 25.65%), fortunately, where suitability for
pine species is high, in contrast with [49], where less than 1% of all the Pinus host species
is D. rhizophagus–free, these differences are explained by the cutoff threshold selected to
15. Forests 2021, 12, 385 15 of 18
obtain the overlap. It has been demonstrated that the analysis of suitability overlap in G is
problematic because it will depend on the extension and distribution of the environmental
gradients in the study area [56]. Despite the importance of identifying SAP–free of SAD,
only the study of Smith et al. (2013) [49] is known.
The overlap (D) of the ‘invasive’ species niche with the ‘conservationism’ species
with the highest percentage of incidence (P. leiophylla) is almost 50%, but a change in
niche of D. mexicanus, relative to the three pine species has been observed (Figure 6a–c).
The niche overlap in similar taxonomic groups of pine species is not very high, on average
D = 0.20 [67]. Studies reveal that one of the two species (with high plant prevalence) shows
a niche shift [20]; this number is quite high, especially in exotic species, it is possible that
the studies reported a shift when there was actually none. Less than 1% of the studies
show niche conservationism. Some authors [73] suggest that dramatic niche changes found
should be carefully interpreted since they are dependent on the methods and data used.
The kernel density method in ecological niche studies (used here) is one of the most robust
and produces the best results [56,57].
5. Conclusions
Not all the models generated in Maxent were statistically significant (α = 0.05).
In ‘kuenm’ it is possible to generate n candidate models and to select a robust model
rather than a random model. The statistical procedure (PCA) was a crucial tool for prese-
lecting climate predictors. By including altitude in the analysis (PCA), it was possible to
identify atypical and erroneous records within the calibration area, which is not possible
through bivariate environmental space. The variables representing extreme temperatures
play an important role in defining species climate suitability; they are also indicators of
climate change and thus evidence that this will affect species distribution, proportional to
their rate of change. The areas of overlapping climate suitability in geographic space and
of niches in environmental space average 84.59 and 46.66%, which indicates small areas of
Pinus species free of the bark beetle that are isolated in the distribution area. The ordination
methods show that pine species have a broader ecological niche, but P. leiophylla and D.
mexicanus were identified as highly vulnerable to climate change. In addition, expansion
of the bark beetle toward new climates is observed and, consequently, toward new ge-
ographic areas following its climate preferences. The areas of high suitability for Pinus,
especially those areas free of suitability areas for D. mexicanus, should be prioritized for
conservation. The redistribution of the bark beetle species is highly probable in the coming
years, consequently, fewer suitable areas for the pine species, free of bark beetle. It is
proposed that, when generating ecological niche models, robust methodologies be used,
considering the association Dendroctonus–Pinus. This study enriches previous knowledge of
the species, improving the delineation of geographic distribution of their ecological niches
and specific climate tolerances, contributing tools for the timely implementation of actions
and strategies for managing the country’s forests for species conservation and preservation.
Author Contributions: F.M.M.-E. performed analysis of the results and writing original draft prepa-
ration of the manuscript. J.M.-G. writing review and editing. R.M.-O., J.Ó.M.L.-D. and J.A.N.-L.
assisted in review. All authors have read and agreed to the published version of the manuscript.
Funding: This research was funded by the Forestry National Commission (CONAFOR) and CONA-
CYT, through project number: 2014, C01-234547.
Acknowledgments: To the National Council of Science and Technology (CONACYT) for the scholar-
ship awarded to the first author for postgraduate studies.
Conflicts of Interest: The authors declare no conflict of interest.
16. Forests 2021, 12, 385 16 of 18
Appendix A
Predictive Species Models
Of the thousands of models generated here, it was revealed that not all were sta-
tistically significant (10 n 99 %), and very few ( 20%) surpassed the omission rate
of 5%, demonstrating that using the default parameters in Maxent does not necessarily
produce the best model. This has already been demonstrated by several researchers [61,62].
Indeed, some authors indicate that the apparent ‘simplicity’ of Maxent (console Maxent)
has caused an exponential increment of modeling studies and that it has only been used
as a ‘black box’, while in the ‘kuenm’ software, it is possible to ‘fine tune’ some of the
model parameters [43], select sets of variables, and validate the predictive capacity of all
the models developed.
Traditionally, the AUC of the ROC has been used as the measure of model fit. However,
this statistic has been criticized [47], especially because of its use of back-ground data
instead of true absences [46]. Moreover, it is highly sensitive to the study scale, resulting
frequently in high AUC values, becoming confused with a good model fit. For this reason,
here, we opted for partial ROC, suggested for ENM [46]; we found values between 1.24
(P. leiophylla) and 1.66 (D. mexicanus), where values close to 1 indicate that what was
observed coincides with random results, while values above 1 is better than random; that
is, model yield is better.
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