This study found that there is a power curve relationship between the length of leaf obstacles placed on Atta colombica ant trails and the time taken by the ants to remove the obstacles. Leaf obstacles over 5cm in length were cut into pieces using the same techniques the ants use for leaf harvesting. Though there were no significant differences found between forests with different rainfall levels or between morning and afternoon time periods, the small sample size means a larger study could reveal differences based on humidity, temperature, and other microclimate variables. Further research is needed to fully examine the effects of these factors on individual ant obstacle removal rates.
Avian Vocalization Adjustment to Urbanization and Anthropogenic Noise_ A Revi...Maxson Jarecki
This document summarizes research on how birds adjust their vocalizations in urban environments in response to anthropogenic noise. It finds that birds that already have high frequency vocalizations are better able to inhabit cities, as low frequency calls are more easily masked by urban noise. Within urban areas, passerine birds with lower baseline frequencies are more likely to further increase their call frequencies. However, evidence suggests frequency changes may not be a directly adaptive response, but rather a byproduct of increasing call volume amplitudes to compensate for noise. The strength of evidence for frequency changes enhancing communication is debated in the literature.
Obstacle Size and Trail–Clearing Activity in Leaf–Cutter Ants, Atta colombicaMaxson Jarecki
This study found that there is a power curve relationship between the length of leaf obstacles placed on Atta colombica ant trails and the time taken by the ants to remove the obstacles. Leaf obstacles over 5cm in length were cut into pieces using the same techniques the ants use for leaf harvesting. Though there were no significant differences found between forests with different rainfall levels or between morning and afternoon time periods, the small sample size means a larger study could reveal differences based on humidity, temperature, and other microclimate variables. Further research is needed to fully examine the effects of these factors on individual ant obstacle removal rates.
While it was traditionally thought that urbanization would decrease avian biodiversity due to habitat loss and other disturbances, this report investigates the effects of urbanization on bird diversity in southwest England. Bird surveys were conducted in 2013 and 2014 at the rural Penryn campus and more urban Streatham campus of the University of Exeter. The results found little difference in bird diversity between years or locations. However, issues with pseudoreplication and differences between sites limit the conclusions that can be drawn. Future studies could improve methodology to better understand the impacts of varying degrees of urbanization on avian communities.
1) The document discusses species interactions within biological communities, including competition, predation, herbivory, and symbiosis.
2) It describes how community diversity and trophic structure characterize communities, noting that higher diversity increases stability and productivity.
3) Certain species, like keystone species, can have outsized impacts on community structure through their ecological roles.
This study investigated the effect of anthropogenic noise on shoaling cohesion in three-spined sticklebacks. The researcher exposed stickleback shoals to white noise playback and found that during noise exposure, the distance between fish in the shoal decreased significantly compared to silent control trials. This suggests that anthropogenic noise causes sticklebacks to group closer together, mirroring their anti-predatory response when threatened by a predator. The findings demonstrate that anthropogenic noise has the potential to influence anti-predatory behavior and vigilance in shoaling fish.
This document provides an overview of broad patterns of evolution as seen in the fossil record. It discusses how the fossil record shows evidence of macroevolutionary changes over time, including the emergence of terrestrial vertebrates and the impact of mass extinctions. Examples of macroevolutionary changes discussed include the origin of flight in birds. The document also examines how plate tectonics and continental drift have influenced the evolution and distribution of organisms by changing global environments and causing the separation of landmasses.
- Plants and fungi were early colonizers of land, with fungi potentially colonizing before plants. They formed symbiotic partnerships through mycorrhizal relationships that helped plants obtain nutrients.
- Key adaptations like a waxy cuticle, specialized tissues for water transport, and stomata allowed early land plants to survive out of water. Fossil evidence shows simple plant structures existed over 400 million years ago.
- Fungi play an essential role in nutrient cycling and decomposition on land through their mycelial networks and ability to secrete digestive enzymes to absorb nutrients. Mycorrhizal relationships with plant roots are mutually beneficial.
Agriculture, forestry and biodiversity conservationMarco Pautasso
Agriculture and biodiversity conservation, forests, urbanization, habitat fragmentation, agri-environment schemes, land use intensity, climate change, human well-being, standing and downed deadwood, United Kingdom, United States of America, Switzerland, forest view and job satisfaction,
Avian Vocalization Adjustment to Urbanization and Anthropogenic Noise_ A Revi...Maxson Jarecki
This document summarizes research on how birds adjust their vocalizations in urban environments in response to anthropogenic noise. It finds that birds that already have high frequency vocalizations are better able to inhabit cities, as low frequency calls are more easily masked by urban noise. Within urban areas, passerine birds with lower baseline frequencies are more likely to further increase their call frequencies. However, evidence suggests frequency changes may not be a directly adaptive response, but rather a byproduct of increasing call volume amplitudes to compensate for noise. The strength of evidence for frequency changes enhancing communication is debated in the literature.
Obstacle Size and Trail–Clearing Activity in Leaf–Cutter Ants, Atta colombicaMaxson Jarecki
This study found that there is a power curve relationship between the length of leaf obstacles placed on Atta colombica ant trails and the time taken by the ants to remove the obstacles. Leaf obstacles over 5cm in length were cut into pieces using the same techniques the ants use for leaf harvesting. Though there were no significant differences found between forests with different rainfall levels or between morning and afternoon time periods, the small sample size means a larger study could reveal differences based on humidity, temperature, and other microclimate variables. Further research is needed to fully examine the effects of these factors on individual ant obstacle removal rates.
While it was traditionally thought that urbanization would decrease avian biodiversity due to habitat loss and other disturbances, this report investigates the effects of urbanization on bird diversity in southwest England. Bird surveys were conducted in 2013 and 2014 at the rural Penryn campus and more urban Streatham campus of the University of Exeter. The results found little difference in bird diversity between years or locations. However, issues with pseudoreplication and differences between sites limit the conclusions that can be drawn. Future studies could improve methodology to better understand the impacts of varying degrees of urbanization on avian communities.
1) The document discusses species interactions within biological communities, including competition, predation, herbivory, and symbiosis.
2) It describes how community diversity and trophic structure characterize communities, noting that higher diversity increases stability and productivity.
3) Certain species, like keystone species, can have outsized impacts on community structure through their ecological roles.
This study investigated the effect of anthropogenic noise on shoaling cohesion in three-spined sticklebacks. The researcher exposed stickleback shoals to white noise playback and found that during noise exposure, the distance between fish in the shoal decreased significantly compared to silent control trials. This suggests that anthropogenic noise causes sticklebacks to group closer together, mirroring their anti-predatory response when threatened by a predator. The findings demonstrate that anthropogenic noise has the potential to influence anti-predatory behavior and vigilance in shoaling fish.
This document provides an overview of broad patterns of evolution as seen in the fossil record. It discusses how the fossil record shows evidence of macroevolutionary changes over time, including the emergence of terrestrial vertebrates and the impact of mass extinctions. Examples of macroevolutionary changes discussed include the origin of flight in birds. The document also examines how plate tectonics and continental drift have influenced the evolution and distribution of organisms by changing global environments and causing the separation of landmasses.
- Plants and fungi were early colonizers of land, with fungi potentially colonizing before plants. They formed symbiotic partnerships through mycorrhizal relationships that helped plants obtain nutrients.
- Key adaptations like a waxy cuticle, specialized tissues for water transport, and stomata allowed early land plants to survive out of water. Fossil evidence shows simple plant structures existed over 400 million years ago.
- Fungi play an essential role in nutrient cycling and decomposition on land through their mycelial networks and ability to secrete digestive enzymes to absorb nutrients. Mycorrhizal relationships with plant roots are mutually beneficial.
Agriculture, forestry and biodiversity conservationMarco Pautasso
Agriculture and biodiversity conservation, forests, urbanization, habitat fragmentation, agri-environment schemes, land use intensity, climate change, human well-being, standing and downed deadwood, United Kingdom, United States of America, Switzerland, forest view and job satisfaction,
This project proposal investigates indirect interactions between two species of leaf-mining moths, Phyllonorycter dubitella and P. salicicolella, that share a parasitoid wasp predator, Achrysocharoides zwoelferi. The researcher hypothesizes that P. dubitella is rare due to apparent competition with the more common P. salicicolella, mediated by their shared predator A. zwoelferi. An experiment will be conducted removing P. salicicolella from some trees to test if P. dubitella populations increase when this competitor is absent, due to a decrease in the shared parasitoid. Fifty willow
Biodiversity conservation and global changeMarco Pautasso
Botanic gardens, human well-being, tree species distribution shifts, invasive species, risk management, sea-level rise, climate according to Walter & Lieth, land use patterns, carbon emissions of conservation biologists, NIMBY, topography
The document investigates the use of nest box schemes as a conservation tool for barn owls. It analyzes 14 years of nest box monitoring data to test two hypotheses: 1) adult barn owl nest box occupancy is positively correlated with the total number of barn owls bred, and 2) adult occupancy is positively correlated with the total offspring produced. The results supported both hypotheses, finding strong positive correlations between occupancy levels and breeding numbers. This suggests that nest boxes are an effective conservation method for barn owls, though their breeding success can still be impacted by environmental factors like weather and prey availability.
66;road mortalities of amphibians hj 22(1)_pp_51-58_ms_11-55[1]Roger Meek
This study monitored amphibian roadkill over six years on low-traffic roads in western France. The common toad and agile frog made up the majority of roadkill at 39% and 25.4% respectively. Roadkill patterns were associated with amphibian migration and habitat near roads. Higher roadkill occurred near woodlands/wetlands and after rainfall, related to migration and foraging behavior. Traffic volume did not correlate with roadkill, but roadkill increased with longer amphibian migration distances.
Seagrass under nutrient load and grazingguestb538ca
The document discusses seagrass systems under the pressures of increasing nutrient loads and grazing. It presents the hypothesis that seagrass meadows can shift between different stable states in response to these pressures. Specifically, it hypothesizes that direct nitrogen toxicity, grazing protection from epiphyte overgrowth, and iron deficiency from organic sediment loading can each trigger positive feedback loops pushing the system towards alternative stable states. The document outlines field and mesocosm experiments designed to test these hypotheses by provoking state shifts through nutrient additions, shade, and the removal of grazers. The results will be used to determine thresholds for state shifts and inform seagrass management and restoration efforts.
Toad Patrols and Toad Body Size BHS Bulletin ArticleRebecca Cattell
This document summarizes a study that compared the body sizes of common toads (Bufo bufo) at two sites in Cambridgeshire, England - one with a long-running toad patrol and one without. The hypothesis was that the patrolled site would have larger average toad sizes since the patrol helps more toads survive to breed multiple times, and toad growth continues throughout life. However, the study found no significant differences in body sizes between the two sites. This suggests that factors other than road mortality, such as high adult mortality from other causes, may be limiting toad population growth and constraining their ultimate body size, regardless of patrols.
Towards an integrated Understanding of Green Space in the European Built Environment
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children
http://scribd.com/doc/239851214
`
Double Food Production from your School Garden with Organic Tech
http://scribd.com/doc/239851079
`
Free School Gardening Art Posters
http://scribd.com/doc/239851159`
`
Increase Food Production with Companion Planting in your School Garden
http://scribd.com/doc/239851159
`
Healthy Foods Dramatically Improves Student Academic Success
http://scribd.com/doc/239851348
`
City Chickens for your Organic School Garden
http://scribd.com/doc/239850440
`
Simple Square Foot Gardening for Schools - Teacher Guide
http://scribd.com/doc/239851110
The passage describes several ecological concepts and methods used to study plant and animal populations and communities, including:
1) Factors that influence species distributions such as temperature, water, light, soil pH, salinity, and nutrients are outlined.
2) Random quadrat sampling and transect methods to study and compare population sizes and distributions are explained.
3) The niche concept including an organism's habitat, feeding activities, and interactions is defined.
4) Examples of species interactions like competition, herbivory, predation, parasitism, and mutualism are given.
5) The principles of competitive exclusion and distinguishing fundamental versus realized niches are explained.
6) Biom
61; road mortalites of reptiles in the vendeeRoger Meek
This document summarizes a study on patterns of reptile roadkill in western France over four years. The study found that two lizard species (Lacerta bilineata and Podarcis muralis) and two snake species (Hierophis viridiflavus and Natrix natrix) that are more active foragers had higher roadkill rates, while two more sedentary snake species (Vipera aspis and Natrix maura) had lower rates. Roadkills occurred throughout the reptiles' active season, with differences in the size classes and monthly frequencies of some species. A positive correlation was found between monthly roadkill counts and live sightings for H. viridiflavus
This article examines how local habitat quality and surrounding landscape affect the development of carabid beetle assemblages on restored landfill sites. The study analyzed carabid species composition, richness, and abundance across 9 restored landfill sites and paired reference sites in the UK. A total of 1014 carabid beetles from 37 species were collected. Seeded landfill sites had higher species richness and diversity than unseeded sites, and more vegetation cover and nearby grasslands also positively impacted carabid assemblages. The restored landfill sites supported generalist beetle species but no rare species. Habitat restoration through seeding and management may improve these sites for carabid conservation.
This study used radio telemetry to track 37 male wood thrush birds over two breeding seasons in coastal Virginia. The researchers then collected data on prey availability and habitat structure within the birds' home ranges. They developed models to examine how prey availability and habitat structure related to the birds' space use patterns within their home ranges. The best model included both prey and habitat variables. Areas of high wood thrush use were associated with greater biomass of spiders and worms, which correlated with higher soil moisture. Bird use also related positively to forest canopy height and snag basal area, and negatively to red oak count and pine basal area. Evaluation of the models found that habitat structure variables explained more variation in bird space use than prey availability alone. This
This study examined the impact of microhabitats on soil invertebrate communities in a 7.7 hectare woodland on the Isle of Wight. Samples from 11 microhabitats including logs, moss, paths, and stumps showed microhabitat-specific species assemblages, with dead wood habitats hosting distinct leaf litter communities. The study also found that samples from the plantation area of the woodland had less diverse invertebrate communities than those from the deciduous area, demonstrating the local impact of land-use change on soil biodiversity. Future work aims to build a global database of studies comparing sites with different land uses to estimate average effects of human impacts on soil communities.
Finlay j.b. ,g.f.esteban & t. fenchel (1998) .protozoan diversity.converging ...chinmeco
The document analyzes two methods used to estimate the global number of free-living ciliated protozoa species: taxonomic analysis and extrapolation from ecological datasets. The methods provide estimates that agree within a factor of two, suggesting around 3,000 total free-living ciliate species globally. This supports the hypothesis that most ciliate species are ubiquitous due to their small size and passive dispersal abilities, rather than having distinct biogeographies. If ciliates are truly ubiquitous, then extrapolating local diversity data from ecological studies to estimate global diversity should match estimates from taxonomic analysis.
This document summarizes a study of riparian bird communities along streams in the Portland, Oregon metropolitan area. The researchers surveyed birds and plants at 54 sites along streams to examine how bird community metrics related to habitat structure and levels of urbanization. They found that total and non-native bird abundance was higher in narrow forested areas, while native bird abundance was greater in narrow forests surrounded by undeveloped land. Native species richness and diversity were positively associated with less developed areas. At smaller spatial scales of 50-100 meters, most relationships between bird communities and canopy cover or road density were strongest. The results suggest that increasing urban forest canopy cover, especially within 450 meters of streams, is the most effective action for conserving native breeding
- The study quantified predation along an urbanization gradient in Denmark using artificial caterpillars that could be identified by marks left by predators.
- In forest habitats, chewing insects exerted the greatest predation pressure (52.1%), while ants and mammals had lower rates. In suburban forests, mammals had the highest rate of predation (22.2%). In urban forests, ants and chewing insects had similar predation rates of 16.4%.
- Predation rates varied seasonally, with chewing insects increasing from spring to autumn in forests, mammals highest in summer in suburban forests, and ants highest in spring in urban forests. Overall, caterpillars were more likely to survive in urban and suburban areas compared
This document provides information on the habitat use and habitat suitability index model for the northern alligator lizard. It describes the species' preferences for grassy, bushy and rocky areas within forested areas. It also outlines variables used in the habitat suitability index model such as average distance to forest edge, percent rock cover, percent shrub canopy cover and percent forest canopy cover. The document indicates the model requires field testing but can help prevent potential habitat degradation and fill knowledge gaps regarding habitat selection for this species.
This document discusses various methods for sampling plant communities. It describes transect and quadrat sampling methods. Transects involve recording plant species along a line or measuring their vertical distribution by digging trenches. Quadrats involve placing a grid and counting organisms within each square. The document also discusses measuring density, coverage, frequency, biomass, and diversity of plant species within samples. It provides formulas for calculating these metrics and comparing values between species.
The document summarizes threats to peatlands in the Congo Basin, which were recently discovered to be the largest tropical peatland complex globally. Climate change is identified as a major threat given its potential to destabilize the entire area's large carbon stocks. Socioeconomic development is increasing risks like hydrocarbon exploration, logging, and plantations. While conservation designations cover much of the area, threats could significantly damage the peatland ecosystems. Immediate action is needed to protect the largely intact peatlands and their carbon while improving local livelihoods.
Presentation of the fall and rise and fall again of eastern hemlock, a foundation tree species of eastern North American forests. Testing the hypothesis that it is a foundation species, modeling its future given climate change scenarios, and validating model results with eddy covariance data
How local-scale processes build up the large-scale response of butterflies to...Alison Specht
The presentation of the CESAB group LOLA-BMS at the 2016 french ecology conference in the FRB-CESAB session "Using a treasury of knowledge to tackle complex ecological questions." Presented by Reto Schmucki.
Water-related bird assemblages in an urban pond ‘archipelago’: Winter pattern...Maria Paola Di Santo
This study reports on the patterns of species occurrence, abundance and richness of a wintering water-related bird assemblage in an ‘archipelago’ of 70 small artificial urban ponds (AUPs) embedded in a metropolitan landscape (Rome, central Italy). A total of 20 species in 26 AUPs were sampled. Only the largest AUPs (>0.1 ha) contained all these species, except for Gallinula chloropus. The highest total mean species abundance was observed in the largest ponds, with statistically significant differences evident among size classes. Two significant spatial thresholds in species abundance and richness were observed (between 0.01 and 0.1 ha; between 0.1 and 1 ha in size). The abundance of single species was correlated with their frequency of occurrence. Ponds in urban areas must be larger than 0.1 ha to host a rich winter assemblage of birds, with a further increase in richness noted with a surface area larger than 1 ha. The highest number of species was observed in the larger ponds (>1 ha). The species richness of each AUP is directly correlated to their size (log-transformed species–area relationship: log S = 3.515 + 0.497 log A; R2 = 0.76). Further research should be conducted to confirm these patterns and to implement information useful for planning and management of artificial ponds in urban areas for this purpose.
Diversity of Soil Fauna and Ecosystem Function tariqulmasud12
Soils are natural resources of utmost. Importance for a number of ecosystem and biosphere processes such as plant production, cycling of organic matter and nutrients, storage of C and water, and release of nitrous oxides, CO2 and methane. Soil degradation, through various processes, is a matter of great concern, since their integrity is absolutely critical to increasing food production (FAO, 1995), and regulating atmospheric fluxes of greenhouse gases (Jenkinson, 199 1 ; Wallace, 1994).
This project proposal investigates indirect interactions between two species of leaf-mining moths, Phyllonorycter dubitella and P. salicicolella, that share a parasitoid wasp predator, Achrysocharoides zwoelferi. The researcher hypothesizes that P. dubitella is rare due to apparent competition with the more common P. salicicolella, mediated by their shared predator A. zwoelferi. An experiment will be conducted removing P. salicicolella from some trees to test if P. dubitella populations increase when this competitor is absent, due to a decrease in the shared parasitoid. Fifty willow
Biodiversity conservation and global changeMarco Pautasso
Botanic gardens, human well-being, tree species distribution shifts, invasive species, risk management, sea-level rise, climate according to Walter & Lieth, land use patterns, carbon emissions of conservation biologists, NIMBY, topography
The document investigates the use of nest box schemes as a conservation tool for barn owls. It analyzes 14 years of nest box monitoring data to test two hypotheses: 1) adult barn owl nest box occupancy is positively correlated with the total number of barn owls bred, and 2) adult occupancy is positively correlated with the total offspring produced. The results supported both hypotheses, finding strong positive correlations between occupancy levels and breeding numbers. This suggests that nest boxes are an effective conservation method for barn owls, though their breeding success can still be impacted by environmental factors like weather and prey availability.
66;road mortalities of amphibians hj 22(1)_pp_51-58_ms_11-55[1]Roger Meek
This study monitored amphibian roadkill over six years on low-traffic roads in western France. The common toad and agile frog made up the majority of roadkill at 39% and 25.4% respectively. Roadkill patterns were associated with amphibian migration and habitat near roads. Higher roadkill occurred near woodlands/wetlands and after rainfall, related to migration and foraging behavior. Traffic volume did not correlate with roadkill, but roadkill increased with longer amphibian migration distances.
Seagrass under nutrient load and grazingguestb538ca
The document discusses seagrass systems under the pressures of increasing nutrient loads and grazing. It presents the hypothesis that seagrass meadows can shift between different stable states in response to these pressures. Specifically, it hypothesizes that direct nitrogen toxicity, grazing protection from epiphyte overgrowth, and iron deficiency from organic sediment loading can each trigger positive feedback loops pushing the system towards alternative stable states. The document outlines field and mesocosm experiments designed to test these hypotheses by provoking state shifts through nutrient additions, shade, and the removal of grazers. The results will be used to determine thresholds for state shifts and inform seagrass management and restoration efforts.
Toad Patrols and Toad Body Size BHS Bulletin ArticleRebecca Cattell
This document summarizes a study that compared the body sizes of common toads (Bufo bufo) at two sites in Cambridgeshire, England - one with a long-running toad patrol and one without. The hypothesis was that the patrolled site would have larger average toad sizes since the patrol helps more toads survive to breed multiple times, and toad growth continues throughout life. However, the study found no significant differences in body sizes between the two sites. This suggests that factors other than road mortality, such as high adult mortality from other causes, may be limiting toad population growth and constraining their ultimate body size, regardless of patrols.
Towards an integrated Understanding of Green Space in the European Built Environment
`
For more information, Please see websites below:
`
Organic Edible Schoolyards & Gardening with Children
http://scribd.com/doc/239851214
`
Double Food Production from your School Garden with Organic Tech
http://scribd.com/doc/239851079
`
Free School Gardening Art Posters
http://scribd.com/doc/239851159`
`
Increase Food Production with Companion Planting in your School Garden
http://scribd.com/doc/239851159
`
Healthy Foods Dramatically Improves Student Academic Success
http://scribd.com/doc/239851348
`
City Chickens for your Organic School Garden
http://scribd.com/doc/239850440
`
Simple Square Foot Gardening for Schools - Teacher Guide
http://scribd.com/doc/239851110
The passage describes several ecological concepts and methods used to study plant and animal populations and communities, including:
1) Factors that influence species distributions such as temperature, water, light, soil pH, salinity, and nutrients are outlined.
2) Random quadrat sampling and transect methods to study and compare population sizes and distributions are explained.
3) The niche concept including an organism's habitat, feeding activities, and interactions is defined.
4) Examples of species interactions like competition, herbivory, predation, parasitism, and mutualism are given.
5) The principles of competitive exclusion and distinguishing fundamental versus realized niches are explained.
6) Biom
61; road mortalites of reptiles in the vendeeRoger Meek
This document summarizes a study on patterns of reptile roadkill in western France over four years. The study found that two lizard species (Lacerta bilineata and Podarcis muralis) and two snake species (Hierophis viridiflavus and Natrix natrix) that are more active foragers had higher roadkill rates, while two more sedentary snake species (Vipera aspis and Natrix maura) had lower rates. Roadkills occurred throughout the reptiles' active season, with differences in the size classes and monthly frequencies of some species. A positive correlation was found between monthly roadkill counts and live sightings for H. viridiflavus
This article examines how local habitat quality and surrounding landscape affect the development of carabid beetle assemblages on restored landfill sites. The study analyzed carabid species composition, richness, and abundance across 9 restored landfill sites and paired reference sites in the UK. A total of 1014 carabid beetles from 37 species were collected. Seeded landfill sites had higher species richness and diversity than unseeded sites, and more vegetation cover and nearby grasslands also positively impacted carabid assemblages. The restored landfill sites supported generalist beetle species but no rare species. Habitat restoration through seeding and management may improve these sites for carabid conservation.
This study used radio telemetry to track 37 male wood thrush birds over two breeding seasons in coastal Virginia. The researchers then collected data on prey availability and habitat structure within the birds' home ranges. They developed models to examine how prey availability and habitat structure related to the birds' space use patterns within their home ranges. The best model included both prey and habitat variables. Areas of high wood thrush use were associated with greater biomass of spiders and worms, which correlated with higher soil moisture. Bird use also related positively to forest canopy height and snag basal area, and negatively to red oak count and pine basal area. Evaluation of the models found that habitat structure variables explained more variation in bird space use than prey availability alone. This
This study examined the impact of microhabitats on soil invertebrate communities in a 7.7 hectare woodland on the Isle of Wight. Samples from 11 microhabitats including logs, moss, paths, and stumps showed microhabitat-specific species assemblages, with dead wood habitats hosting distinct leaf litter communities. The study also found that samples from the plantation area of the woodland had less diverse invertebrate communities than those from the deciduous area, demonstrating the local impact of land-use change on soil biodiversity. Future work aims to build a global database of studies comparing sites with different land uses to estimate average effects of human impacts on soil communities.
Finlay j.b. ,g.f.esteban & t. fenchel (1998) .protozoan diversity.converging ...chinmeco
The document analyzes two methods used to estimate the global number of free-living ciliated protozoa species: taxonomic analysis and extrapolation from ecological datasets. The methods provide estimates that agree within a factor of two, suggesting around 3,000 total free-living ciliate species globally. This supports the hypothesis that most ciliate species are ubiquitous due to their small size and passive dispersal abilities, rather than having distinct biogeographies. If ciliates are truly ubiquitous, then extrapolating local diversity data from ecological studies to estimate global diversity should match estimates from taxonomic analysis.
This document summarizes a study of riparian bird communities along streams in the Portland, Oregon metropolitan area. The researchers surveyed birds and plants at 54 sites along streams to examine how bird community metrics related to habitat structure and levels of urbanization. They found that total and non-native bird abundance was higher in narrow forested areas, while native bird abundance was greater in narrow forests surrounded by undeveloped land. Native species richness and diversity were positively associated with less developed areas. At smaller spatial scales of 50-100 meters, most relationships between bird communities and canopy cover or road density were strongest. The results suggest that increasing urban forest canopy cover, especially within 450 meters of streams, is the most effective action for conserving native breeding
- The study quantified predation along an urbanization gradient in Denmark using artificial caterpillars that could be identified by marks left by predators.
- In forest habitats, chewing insects exerted the greatest predation pressure (52.1%), while ants and mammals had lower rates. In suburban forests, mammals had the highest rate of predation (22.2%). In urban forests, ants and chewing insects had similar predation rates of 16.4%.
- Predation rates varied seasonally, with chewing insects increasing from spring to autumn in forests, mammals highest in summer in suburban forests, and ants highest in spring in urban forests. Overall, caterpillars were more likely to survive in urban and suburban areas compared
This document provides information on the habitat use and habitat suitability index model for the northern alligator lizard. It describes the species' preferences for grassy, bushy and rocky areas within forested areas. It also outlines variables used in the habitat suitability index model such as average distance to forest edge, percent rock cover, percent shrub canopy cover and percent forest canopy cover. The document indicates the model requires field testing but can help prevent potential habitat degradation and fill knowledge gaps regarding habitat selection for this species.
This document discusses various methods for sampling plant communities. It describes transect and quadrat sampling methods. Transects involve recording plant species along a line or measuring their vertical distribution by digging trenches. Quadrats involve placing a grid and counting organisms within each square. The document also discusses measuring density, coverage, frequency, biomass, and diversity of plant species within samples. It provides formulas for calculating these metrics and comparing values between species.
The document summarizes threats to peatlands in the Congo Basin, which were recently discovered to be the largest tropical peatland complex globally. Climate change is identified as a major threat given its potential to destabilize the entire area's large carbon stocks. Socioeconomic development is increasing risks like hydrocarbon exploration, logging, and plantations. While conservation designations cover much of the area, threats could significantly damage the peatland ecosystems. Immediate action is needed to protect the largely intact peatlands and their carbon while improving local livelihoods.
Presentation of the fall and rise and fall again of eastern hemlock, a foundation tree species of eastern North American forests. Testing the hypothesis that it is a foundation species, modeling its future given climate change scenarios, and validating model results with eddy covariance data
How local-scale processes build up the large-scale response of butterflies to...Alison Specht
The presentation of the CESAB group LOLA-BMS at the 2016 french ecology conference in the FRB-CESAB session "Using a treasury of knowledge to tackle complex ecological questions." Presented by Reto Schmucki.
Water-related bird assemblages in an urban pond ‘archipelago’: Winter pattern...Maria Paola Di Santo
This study reports on the patterns of species occurrence, abundance and richness of a wintering water-related bird assemblage in an ‘archipelago’ of 70 small artificial urban ponds (AUPs) embedded in a metropolitan landscape (Rome, central Italy). A total of 20 species in 26 AUPs were sampled. Only the largest AUPs (>0.1 ha) contained all these species, except for Gallinula chloropus. The highest total mean species abundance was observed in the largest ponds, with statistically significant differences evident among size classes. Two significant spatial thresholds in species abundance and richness were observed (between 0.01 and 0.1 ha; between 0.1 and 1 ha in size). The abundance of single species was correlated with their frequency of occurrence. Ponds in urban areas must be larger than 0.1 ha to host a rich winter assemblage of birds, with a further increase in richness noted with a surface area larger than 1 ha. The highest number of species was observed in the larger ponds (>1 ha). The species richness of each AUP is directly correlated to their size (log-transformed species–area relationship: log S = 3.515 + 0.497 log A; R2 = 0.76). Further research should be conducted to confirm these patterns and to implement information useful for planning and management of artificial ponds in urban areas for this purpose.
Diversity of Soil Fauna and Ecosystem Function tariqulmasud12
Soils are natural resources of utmost. Importance for a number of ecosystem and biosphere processes such as plant production, cycling of organic matter and nutrients, storage of C and water, and release of nitrous oxides, CO2 and methane. Soil degradation, through various processes, is a matter of great concern, since their integrity is absolutely critical to increasing food production (FAO, 1995), and regulating atmospheric fluxes of greenhouse gases (Jenkinson, 199 1 ; Wallace, 1994).
This document summarizes two field studies that evaluated how well different invertebrate taxa performed as environmental or biodiversity indicators compared to plants, vertebrates, and each other. The studies were conducted on restored bauxite and mineral sand mines in Western Australia. At both sites, ant assemblage composition reflected trends in other taxa to a greater degree than plants, vertebrates, or birds. Taking into account data yield per unit effort, ants performed moderately well as environmental indicators and extremely well as biodiversity indicators. Overall, most invertebrate groups provided a better return on effort than vertebrates as bioindicators.
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.
Guerreiro (2014). Biodiversity distribution in the western Sahara-Sahel the r...Ricardo Guerreiro
This document provides background information on a fieldwork internship conducted in North-West Africa to study biodiversity distribution patterns. The internship involved sampling amphibians and reptiles across five ecoregions in Morocco, Mauritania and Mali over 48 days. A total of 47 taxa were found with diversity increasing from north to south. Analyses of niche breadth for 11 taxa showed environmental variation impacts distribution. Distribution of four gecko species was evaluated against environmental factors using GIS, finding preferences for different temperature ranges between closely related species. Overall biodiversity follows a north-south precipitation gradient, and there are apparent ecological niche differences between Tarentola gecko taxa.
This study analyzed spatial and temporal variation in plant community composition and species cover following dune restoration along the Devesa de Albufera in Valencia, Spain from 1988 to 2004. Restoration involved reintroducing native plant populations to different sections of coastline. The current study compared current species composition and cover across the length of the coastline and across dune faces to differences imposed during initial restoration. Non-metric multidimensional scaling detected significant differences both across dune faces, related to ecological gradients, and across coast sections, related to differences in initial restoration protocols, with a trend toward homogenization over time.
This study examined potential mechanisms for fern species coexistence in Catlins forests of New Zealand. The study analyzed differences in environmental traits between sites characterized by different dominant tree types (gymnosperm or angiosperm), and differences in functional traits between common fern species. Results showed soil temperature varied significantly between sites, with higher temperatures under gymnosperm trees. However, other environmental traits did not differ between sites. Significant differences were found for several functional traits (specific leaf area, specific root length, pinnae thickness, water use efficiency) between fern species. This supports the hypothesis that functional trait diversity, rather than environmental heterogeneity, is the prevailing mechanism allowing coexistence of fern species in these forests.
A R T I C L E SCaptivity for Conservation Zoos at a Cross.docxransayo
A R T I C L E S
Captivity for Conservation? Zoos at a Crossroads
Jozef Keulartz
Accepted: 22 February 2015 / Published online: 13 March 2015
� The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract This paper illuminates a variety of issues that speak to the question of
whether ‘captivity for conservation’ can be an ethically acceptable goal of the
modern zoo. Reflecting on both theoretical disagreements (animal protectionists vs.
wildlife conservationists) and practical challenges (the small percentage of endan-
gered species actually exhibited in zoos, disappointing success of reintroduction
programs), the paper explains why the ‘Noah’s Ark’ paradigm is being replaced by
an alternative ‘integrated approach.’ It explores the changes in the zoo’s core tasks
that the new paradigm implies. And it pays special attention to the changes that
would have to be made in zoos’ collection policies: connection with in situ projects,
emphasizing local species and the local biogeographical region, exchange of ani-
mals among zoos and between zoos and wildlife, and a shift towards smaller spe-
cies. Finally the question will be addressed whether the new paradigm will achieve a
morally acceptable balance between animal welfare costs and species conservation
benefits.
Keywords Future zoo � Animal welfare � Species conservation � Metapopulation
management
Introduction
Today, the animal world is under severe attack as a result of two strongly
interconnected global processes. On the one hand, global environmental changes
J. Keulartz (&)
Emeritus Professor of Environmental Philosophy, Radboud University, Nijmegen, The Netherlands
e-mail: [email protected]
J. Keulartz
Wageningen University, Wageningen, The Netherlands
123
J Agric Environ Ethics (2015) 28:335–351
DOI 10.1007/s10806-015-9537-z
such as climate change, land use and land cover change, deforestation and
desertification have a disruptive impact on plant and animal life. Entire populations
are being confronted with the alternative to abandon their original habitat or to go
extinct. On the other hand, globalization causes massive dislocations of entire
populations. As trade, travel, transport and tourism boom, the world is becoming
more and more borderless and, by the same token, it is becoming increasingly
vulnerable to invasive species. Since globalization took off, more plants and animals
have become globetrotters than ever before (Keulartz and Swart 2012).
Because animals are constantly on the move worldwide as a result of these global
processes, traditional in situ (place-based) conservation methods seem no longer
sufficient to save threatened species (Sandler 2012). The magnitude of anthro-
pogenic environmental stress from bioinvasion, habitat fragmentation, nitrogen
deposition, biodiversity loss, and, above all, climate change, makes it unavoidable
to replace the hands-off approach that has guided mainstream species con.
This study used habitat suitability models at multiple spatial scales from 100-4000 meters to understand how 10 bat species in the Western Ghats region of India respond to different land uses, including tea and coffee plantations. The models found that most bat species showed a positive response to coffee plantations with native shade trees and forest fragments, but a negative response to more cleared tea plantations. Small-scale habitat variables like percentage tea plantation cover and distance to water were strongest predictors, likely due to bats' high mobility. While bats responded negatively to tea plantations overall, tea-dominated landscapes containing forest and shade coffee can still support many bat species.
This document analyzes suitable habitat for gopher tortoises at the Jacksonville Arboretum and Gardens. It uses GIS map analysis to survey the Arboretum and determine where suitable tortoise habitat exists based on factors like land cover, soil density, and distance from habitat edges. Three maps were created analyzing these factors and reclassified on a 5-point scale of suitability. The maps were combined through weighted sum analysis into a final suitability map to identify potential restoration sites that could increase tortoise populations at the Arboretum.
This study developed empirical models to predict canopy arthropod biomass in arctic tundra based on measurements of the normalized difference vegetation index (NDVI). Models were created using data across four growing seasons and four distinct tundra vegetation communities in Alaska. The overall model, across all communities, explained 63% of variance in arthropod biomass. Models for individual communities explained 74-87% of variance. This research shows NDVI can quantify spatial and temporal dynamics of arthropod biomass, and lays groundwork for using air and satellite data to assess arthropod communities at larger scales.
This document summarizes a study that compared the habitat structure, invertebrate assemblages, and fish diets associated with patches of the native floating plant pennywort versus the introduced floating plant water hyacinth in the Sacramento-San Joaquin Delta of California. The study found several key differences between the two plants: 1) pennywort patches had higher leaf and insect densities and different insect assemblage compositions than hyacinth patches; 2) hyacinth roots in the water column had significantly more surface area than pennywort roots; and 3) densities and taxonomic compositions of aquatic invertebrates generally differed between the two plant types. The introduction of water hyacinth caused significant ecological alterations to the surrounding community
Status of Bushbuck (Tragelaphus scriptus) and Buffalo (Syncerus caffer) in th...AI Publications
The study titled “Status of Bushbuck (Tragelaphus scriptus) and Buffalo (Syncerus caffer) in the North and South Eastern parts of the Kimbi-Fungom National Park (K-FNP) of the North West Region of Cameroon” was carried out in the rainy season from 1st May to 31st July 2015. The general objective was to contribute to the conservation of bushbuck and Buffalo in the K-FNP through the establishment of status of mammals which will serve as a guide for management decisions. The methodology employed was the “recce-walk”. Twenty seven (27) lines transects of 2 km long each were walked making a total effort of 53km. One hundred and fifty six (156) questionnaires were administered to the local population, twenty one (21) semi-structured interviews to households and seven (7) focus group discussions with local chiefs and notables were used to get local people’s perceptions about wildlife conservation in the NP. Results revealed a total of 13 species of mammals within the NP belonging to 6 families. The Bovidae family had the highest number of species represented by the buffalo (Syncerus caffer), bushbuck (Tragelaphus scriptus), the blue duiker (Cephalophus monticola) and the red duiker (Cephalophus dorsalis). The buffalo and the bushbuck recorded encounter rates of 0.85 and 0.34sign/km respectively. The Buffalo had a higher density in the North East of the South East compartment of the park while the bushbuck had a higher density in the south west of the north east compartment. There was a strong relationship (R2=0.792) between the encounter rate of mammals and anthropogenic activities. Ninety two (92.31%) of respondents recognized the importance of the NP because they depended on it for collection of NTFP’s (34.60%), hunting of Bushmeat (12.80%), fuel wood gathering (7.70%), religious activities (6.40%), agricultural land (5.10%), harvesting of medicinal plants(5.10%), source of clean water (5.10%), traditional rituals (3.80%) and traditional medicine harvesting (2.6%). Ninety seven percent (97.2%) supported wildlife conservation because of its touristic, aesthetic and for sustainability. Thirty four percent (34.60%) of the respondents were aware of community implication in managing the NP. K-FNP is poor in species abundance, species richness and flagship species. Associated benefits from ecotourism are far-fetched coupled with encroachment by grazers. We therefore recommend that the government, councils, NGOs and the local communities should step up conservation efforts.
Status of Bushbuck (Tragelaphus scriptus) and Buffalo (Syncerus caffer) in th...AI Publications
The study titled “Status of Bushbuck (Tragelaphus scriptus) and Buffalo (Syncerus caffer) in the North and South Eastern parts of the Kimbi-Fungom National Park (K-FNP) of the North West Region of Cameroon” was carried out in the rainy season from 1st May to 31st July 2015. The general objective was to contribute to the conservation of bushbuck and Buffalo in the K-FNP through the establishment of status of mammals which will serve as a guide for management decisions. The methodology employed was the “recce-walk”. Twenty seven (27) lines transects of 2 km long each were walked making a total effort of 53km. One hundred and fifty six (156) questionnaires were administered to the local population, twenty one (21) semi-structured interviews to households and seven (7) focus group discussions with local chiefs and notables were used to get local people’s perceptions about wildlife conservation in the NP. Results revealed a total of 13 species of mammals within the NP belonging to 6 families. The Bovidae family had the highest number of species represented by the buffalo (Syncerus caffer), bushbuck (Tragelaphus scriptus), the blue duiker (Cephalophus monticola) and the red duiker (Cephalophus dorsalis). The buffalo and the bushbuck recorded encounter rates of 0.85 and 0.34sign/km respectively. The Buffalo had a higher density in the North East of the South East compartment of the park while the bushbuck had a higher density in the south west of the north east compartment. There was a strong relationship (R2=0.792) between the encounter rate of mammals and anthropogenic activities. Ninety two (92.31%) of respondents recognized the importance of the NP because they depended on it for collection of NTFP’s (34.60%), hunting of Bushmeat (12.80%), fuel wood gathering (7.70%), religious activities (6.40%), agricultural land (5.10%), harvesting of medicinal plants(5.10%), source of clean water (5.10%), traditional rituals (3.80%) and traditional medicine harvesting (2.6%). Ninety seven percent (97.2%) supported wildlife conservation because of its touristic, aesthetic and for sustainability. Thirty four percent (34.60%) of the respondents were aware of community implication in managing the NP. K-FNP is poor in species abundance, species richness and flagship species. Associated benefits from ecotourism are far-fetched coupled with encroachment by grazers. We therefore recommend that the government, councils, NGOs and the local communities should step up conservation efforts.
Rotem et al 2011 The Effect of anthropogenic resources on the space-use patt...Guy Rotem
This study examined how the space-use patterns of golden jackals are affected by proximity to human villages in Israel. The researchers radio-tracked 16 jackals, 8 near villages and 8 further away. They found that jackals near villages had smaller home ranges and core areas than those further away. Jackals near villages also moved less during the day than those in more natural areas. However, nighttime movement did not differ between the two groups, though jackals near villages moved in a less directional manner. The presence of abundant, predictable food sources from human villages compressed jackal space use and altered their movement patterns.
- The document summarizes a study that used environmental DNA (eDNA) analysis to assess the biodiversity of restored bivalve populations at two sites in New York City - Soundview Park and Freshkills Park.
- eDNA was extracted from water and sediment samples to identify eukaryotic organisms without directly observing them. This allows for a more efficient biodiversity analysis compared to traditional methods.
- The study aims to compare biodiversity between restored areas with bivalves and control sites without bivalves to evaluate the impact of restoration efforts. Preliminary results from Soundview Park found over 270 eukaryotic orders present based on eDNA sequencing.
Reproductive phenologies in a diverse temperate ant faunaMelissa Geraghty
This document summarizes a study on the reproductive phenology (timing of reproduction) of ants in the Great Smoky Mountains National Park. The study addressed three questions: 1) Are the reproductive flights of closely related ant species more staggered in time compared to distantly related species? 2) Are the flights of individual ant species synchronous or asynchronous? 3) Does reproductive timing vary with elevation or between years? The study found that closely related species tended to have similar flight times, flights were generally synchronous within species, and flight phenology varied with elevation but not greatly between years. It provides background on ant reproduction and mating systems and describes the methods used to analyze flight data collected from Malaise traps over multiple years.
Trends in Macrophyte Diversity in Anthropogenic Perturbed Lentic Ecosystems w...Premier Publishers
Aquatic macrophytes hold several niches within the ecosystem, including inter alia water purification, carbon sequestration and serve as microhabitats for aquatic insects. These dynamic roles make macrophytes good indicators of current environmental conditions. Hence assessing their abundance in line with wetland ecosystem dynamics and function is essential. Frequency of occurrence and density values were estimated, using twenty (20) 2 m x 2 m quadrats for each macrophyte encountered. The results of the study revealed twenty-one (21) macrophytes belonging to 16 families. These ponds varied markedly in terms of species composition and in numerical strength such that Polygonum lanigerum (1143+175st/ha), Setaria verticillata (337.5+ 32.8st/ha), Azolla pinnata (337.7+ 16.4 st/ha) recorded high density values while Lagenaria breviflora (18.7±2.19), Sida acuta (18.75±5.30), Ludwigia erecta (18.7±0.15) and Milletia aboensis (18.7±0.03) were the least abundant species. Pond A and D with 11 taxa each had the higher Shannon-Wiener (2.192, 2.214) and Simpson (0.8699, 0.8787) diversity indices respectively when compared to the other ponds. On the contrary, pond C with four taxa had the least Shannon-Wiener and Simpson diversity indices (1.253, 0.6782) respectively. Equitability and evenness ranged between 0.914 - 0. 952 and 0.814 - 0.900 respectively. Bray and Curtis cluster analysis showed that pond B was the most dissimilar compared to other ponds in terms of the taxa composition.
Spies - Influence of phorid fly (Family Phoridae) sound on the behavior of le...Nicolas Spies
This study examined how the leaf-cutting ant Atta cephalotes responds behaviorally to the sound of phorid flies, which are parasitoid insects that prey on A. cephalotes. The researcher observed 4 variables in 17 A. cephalotes nests when exposed to 3 stimuli: no sound, the sound of cicadas, and the sound of phorid flies. The variables observed were the number of minor workers entering and exiting nests, the number of minor workers on foraging material, and the speed of foraging material entering nests. While some differences were observed across stimuli for the variables, the only statistically significant difference was in the number of minor workers exiting nests, which increased when
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.
Similar to Obstacle Size and Trail–Clearing Activity in Leaf–Cutter Ants, Atta colombica (20)
Obstacle Size and Trail–Clearing Activity in Leaf–Cutter Ants, Atta colombica
1. Tropical Ecology • February 2015 • Ecology and Evolutionary Biology
Obstacle Size and Trail–Clearing
Activity in Leaf–Cutter Ants, Atta
colombica
Maxson Jarecki
Princeton University
mjarecki@princeton.edu
Abstract
This study on Atta colombica leaf obstacle removal found that there is a power curve relationship
between leaf obstacle length and its removal time. Leaf obstacles over 5cm long were cut using the same
techniques as used in leaf harvesting. This study was conducted across 3 forests of varying rainfall levels
in Panamá. Though there were no significant differences found between forests and time periods (morning
and afternoon), a larger study may reveal differences based on humidity, elevation, temperature, sun
exposure, and microclimate variation due to weather and vegetation. Further research must be conducted
to fully examine the effect these variables have on the individual obstacle removal rates of these forests.
Keywords: Atta colombica; rainfall gradient; Panamá; trail maintenance; obstacle removal.
I. Introduction
A
tta colombica is a species of fungus grow-
ing leaf–cutter ant; its range reaches
throughout the Neotropics (Ghazoul
and Sheil 2010). It is distinguished from its
relative, Atta cephalotes, by a missing tuft of
reddish hair, and by its aboveground refuse
dumps, as cephalotes dump underground. They
are part of the myrmicine tribe Attini, along
with macrotermitine termites and some wood–
boring beetles, members of which are distin-
guished by their unique ability to cultivate and
consume fungi (Wirth et al. 2003). Atta colom-
bica colonies can contain several million ants,
and they can build large nests as deep as 6
meters underground (Ghazoul and Sheil 2010).
Their farmed fungus, Leucoagarius gongylopho-
rus, only exists in the wild within leaf–cutter
ant nests (Ghazoul and Sheil 2010).
Atta colombica antennae, mouthparts, and
legs each contribute to the obstacle removal
process that this study investigates. Dr. M.V.
Brian provides a good summary of ant phys-
iology in his book, Ants (1977). Their anten-
nae allow Atta to process the size and shapes
of objects in their environment. They can be
moved, and can be spread wide apart to com-
prehend large objects, or brought close together
to sense objects less than a millimeter in diam-
eter. The antennae also detect chemicals and
pheromones laid down by other foragers, in ad-
dition to sensing vibrations in the substratum.
Atta mouths are surrounded and enclosed by
several pairs of articulated appendages, the
most prominent of which are the mandibles
(Brian 1977). These main jaws are hollow, but
are composed of thick walls. They are solidly
attached to the ant head and can be opened
widely, and closed tightly. Finally, Atta legs
each have five main joints. The outermost joint,
however, is finely articulated by further small
joints to make a flexible “foot.” Each leg is ex-
ceptionally maneuverable, and can move over
rough and irregular terrain; even up vertical
and overhanging surfaces. The ant’s hind legs
are the longest, and are long enough to lift
their body clear off the ground (Brian 1977).
These leaf–cutting ants are the most dom-
inant herbivores in the New World tropics
1
2. Tropical Ecology • February 2015 • Ecology and Evolutionary Biology
(Wilson 1986), and as “generalist herbivores,”
Colombica ants have an enormous effect on the
ecosystems they inhabit (Wirth et al. 2003).
Their role as agricultural pests have prompted
leaf–cutting ants like Atta colombica to be
among the most studied tropical insects (We-
ber 1972; Hölldobler and Wilson 1990; Fowler
et al. 1990). Because of their role as pests, most
of the research surrounding these tropical ants
revolves around their control (Vander Meer et
al. 1990). Their yearly neotropical agricultural
damage has been valued to cost thousands of
millions of dollars (Cherrett 1986). However,
there is also much research regarding Atta be-
havior.
Specifically, their foraging strategies have
been a topic of inquiry. The distribution of Atta
foraging over a large area through trails, rather
than simply foraging around the nest, has been
a major subject of study (Cherrett 1986; Fowler
and Styles 1980; Rockwood and Hubbell 1987;
Shepherd 1982). Foraging efforts are arranged
through these trails to promote the discovery
of items in productive areas (Shepherd 1982).
Also, the recruitment pheromone laid down
on these trails can convey information about
location and quality of resources (Hangartner
1969). There is research on the performance of
workers utilizing trails (Lutz 1929; Hubbell et
al. 1980; Rudolph and Loudon 1986, Lighton
et al. 1987, Waller 1989; Shutler and Mullie
1991; Wetterer 1994; Burd 1995). There are
also many studies on the use of trail systems
(Fowler and Robinson 1979; Fowler and Stiles
1980; Shepherd 1982; Rockwood and Hubbell
1987). There is less information, though, on the
origins of these foraging trails: where they are,
how they are constructed, and how they are
maintained (Shepherd 1985; Farji Bener and
Sierra 1993; Howard 2001).
Foraging trails allow Atta ants to locate re-
sources once they have exited the nest (Höll-
dobler 1977; Shepherd 1982; Fowler and Stiles
1980). Trails have also been linked to reduc-
ing aggressive encounters between neighboring
colonies whose resource areas overlap (Vilela
and Howse 1986; Farji Bener and Sierra 1993).
Their trails are broken into two types, “trunk”
trails (like the trunk of a tree), and ephemeral
trails (Howard 2001). These trunk trails are
fairly permanent, persisting from a few months
to several years (Howard 2001). Colombica
colonies manage trail systems that average
267 meters in length, and build an estimated
2.7 kilometers of trail per year (Howard 2001).
Through his calculations, Howard concluded
that the energetic costs of trail clearing are
negligible in the context of the vast number
of available workers and their rate of harvest
(2001). It is interesting to note that these long–
lasting trails persist despite Atta’s foraging on
patchy and ephemeral leaf resources (Rock-
wood 1975; Fowler and Stiles 1980; Shepherd
1985). These trails can be easily identified in
the forest, as they are often clear of debris. This
trail clearing has been shown to facilitate more
effective locomotion (Rockwood and Hubbell
1987). In fact, Rockwood and Hubbell found
that colony investment in trail–making repaid
between four– and ten–fold in reduced travel
cost (1987). Also, the more effective applica-
tion of trail pheromones to the smoother sub-
strate offered by a cleared trail may increase
the strength and persistence of these trunk
trails, which may allow ants to relocate and
exploit resources more effectively (Wirth et al.
2003). Hölldobler and Lumsden developed a
cost–benefit equations to examine the energetic
frictional cost of trail locomotion and trail con-
struction (1982).
Cf = gNtot
Cf is frictional cost, Ntot is the number of
loads carried, and g is a cost–per–ant coeffi-
cient. G is higher in a litter–covered forest floor
and lower in a cleared area (Hölldobler and
Lumsden 1980) (Fig. 1).
Ct = aNmax + bNmaxT
Ct is the cost of clearing and maintaining
a trail. It increases with the area of the trail,
aNmax, and the amount of time the trail is used,
bNmax (Hölldobler and Lumsden 1980) (Fig. 1).
2
3. Tropical Ecology • February 2015 • Ecology and Evolutionary Biology
Figure 1: Visual representation of the costs and benefits
of trail–clearing in Atta colombica.
Atta ants in a colony are divided into dif-
ferent castes, primarily based on head size
(Wirth et al. 2003). Lugo et al. (1973) esti-
mated that up to 75% of ants on trails at a
given time do not carry leaves. They suppose
that these ants are the ones most involved in
trail–clearing. The most frequent head width
among leaf carriers is between 2.0 and 2.2mm
(Wirth et al. 2003). Howard found that larger
workers whose headwidths measure between
2.2 and 2.9mm are most likely to be involved
in trail clearing (2001). His study confirmed
that ants clearing trails are significantly larger
than those carrying leaves. Ants involved in
trail–clearing exhibit high task fidelity; clearers
tend to clear, while foragers forage (Howard
2001). Small litter items are carried off trails,
while larger items are made smaller through
the same leaf–cutting techniques Atta colombica
ants use during foraging.
This investment in altering the obstacle
greatly increases its removal energy cost, but
makes its removal possible (Howard 2001). His
study outlined the time and energy costs of
trail–clearing on a macro scale; those of a
colony. He found that the costs of removing a
kilogram of litter were approximately 3,359 ant–
hours and 4.6 kJ of collective energy (Howard
2001). He then estimated that the total cost
of trail–clearing to a colony averaged 11,000
ant–days of work (2001). The yearly energetic
cost, though, was the equivalent of just 8,000
leaf–loads (Howard 2001). There is a major
discrepancy between the importance of trail–
clearing activity and its cost. Rockwood and
Hubbell (1987) found that there can be a ten–
fold reduction in travel cost when a trail is
properly cleared. However, this instrumental
activity takes only 8,000 leaf–burdens of en-
ergy yearly. This annual cost can be recovered
in less than a day by an average–size colony
(Howard 2001)! If these findings are correct,
then trail–clearing may be one of the most ef-
fective productivity–enhancing behaviors these
social insects perform. While Howard’s study
was a colony–wide investigation into time in-
vestment, my own study involves an in–depth
look at this phenomenon on a micro scale. I in-
vestigated the relationship between leaf length
and obstacle removal time in Atta colombica
colonies during trail–clearing.
II. Methods
I conducted this study through three forests in
Panamá over a rainfall gradient:
Pipeline Road: A lowland wet evergreen for-
est with 2,131 mm rainfall per year at
27m elevation.
Parque Natural Metropolitano: A lowland
semi–deciduous forest with 1,850 mm
rainfall per year at 30m elevation.
San Lorenzo: A lowland wet evergreen forest
with 3,152 mm rainfall per year at 130m
elevation.
Over the course of 9 study days during the
month of February, I located 5 Atta colombica
colonies per forest. I used these sites to test
their leaf obstacle removal speed. I selected per-
manent “trunk” trails and excluded all trails
that were not approximately 75% cleared; trail
3
4. Tropical Ecology • February 2015 • Ecology and Evolutionary Biology
clearance level was determined visually. I laid
leaves of lengths between 1 cm and 24 cm down
in the middle of these trails and timed colonies’
obstacle removal times (ORTs henceforth).
Leaves were selected from the Swietenia
macrophylla, the big–leaf mahogany tree. Macro-
phylla is an endemic tree species that offers a
wide range of leaf lengths in a standard shape.
I gathered a large batch of macrophylla leaves
of various sizes and stored them flat in plas-
tic bags, creating a vacuum by sucking the air
from each bag, and storing them in the dark.
This was to minimize day–by–day variations in
moisture content.
I also performed an in–lab analysis on Swi-
etenia macrophylla leaf length, width, mass, and
surface area correlations (Fig. 1). This work
verified that there was a consistent linear rela-
tionship between these variables. Leaf lengths
and widths were determined with a ruler, and
leaf mass was determined with a scale. Fi-
nally, surface area calculated using computer–
analyzed photos of each leaf, through the pro-
gram ImageJ R
.
Finding complete macrophylla leaves less
than 4 cm long proved impossible, so I cre-
ated leaf fragments by cutting larger leaves
into the correct shape. I selected removal sites
at least 10 feet apart from one another to min-
imize the effect obstacles may have on each
others’ ORT. Leaves were laid down horizon-
tally across the trail to maximize blockage; each
leaf was placed upside–down to create a small
hill, increasing each obstacle’s effect on forager
movement.
I began ORT timing from the moment the
first unladen ant touched the leaf, and ended
when 95% of ants involved left the site. I also
noted the occurrence of leaf–cutting behavior
on the obstacle, as some obstacles were cut and
some were not.
Figure 2: Length and width, mass, and surface area have
linear relationships (N = 60). Linear regres-
sion in JMP 11 found significance of r2 = 0.79,
r2 = 0.91, and r2 = 0.90, respectively. Each
regression revealed a P < .0001.
I analyzed my leaf length and ORT mea-
surements using CurveExpert Professional Ver-
sion 1.2.2 (2011), a comprehensive data analysis
software by D.G. Hyams.
4
5. Tropical Ecology • February 2015 • Ecology and Evolutionary Biology
III. Results
All data gathered during the study reflects a
power curve relationship between leaf length
and obstacle removal time (n = 104, r2 = 0.619)
(Fig. 1a). The power curve equation is:
y = axb
Each location and time period indepen-
dently had power curve relationships between
leaf length and obstacle removal time (Fig. 1b–
1f).
Figure 3: Figures 1a—-1f, left to right. Each curve
follows the power equation y = axb. The
outer shaded area represents “b” standard er-
ror, while the inner represents that of “a".
The variables a and b for each data set’s
y = axb equation are located in Table 1. Their
standard errors are included in italics.
Table 1: Regression values for each data set, to be input
to the power equation y = axb.
I projected average ORTs for for 3 leaf
lengths in Table 2 using the above data. By
checking the ranges of these values according
to their standard error I discovered that there
is no significant difference between these lo-
cations and time periods. However, a larger
sample size may reveal significance.
Table 2: ORT estimations for 3 different leaf sizes. These
times were calculated from regressions of y =
axb from each site and time period.
Leaf length and presence or absence of cut-
ting were highly correlated (Kruskall–Wallis
non–parametric t–test: Z = –7.21, p<0.001) (Fig.
2). Leaves above 12 cm in length were always
cut. The two outlying data points above 12
cm in the “no” column were the only ones
placed on a severe incline, which allowed ants
to remove them quickly and without cutting.
Leaves between 12 cm and 5 cm varied, pos-
sibly due to factors outlined in the discussion.
Leaves below 5cm were never cut.
Figure 4: Leaf length and presence or absence of cutting.
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6. Tropical Ecology • February 2015 • Ecology and Evolutionary Biology
IV. Discussion
The most significant finding of this study is the
power curve relationship found between leaf
length and ORT. One would assume that this
trail-clearing phenomena would increase lin-
early: a 5 cm object taking 5 minutes, and a 25
cm object taking 25. Instead, this exponential
increase causes a drastic difference between
objects of of different sizes; a 5 cm leaf takes 5
minutes, but a 25 cm leaf actually takes 82 (Ta-
ble 2). If there is such a significant presence of
obstacle-removing ants patrolling these trunk
trails (Lugo et al. 1973) then why is there such
a time discrepancy between the removal and
small and large leaves?
Ants can carry up to 10x their own weight
(Brian 1977); this implies that their combined
efforts should be extremely effective in moving
large objects. However, the random movement
of individual ants involved in trail-clearing
renders this strength futile, as they are often
pulling against each other. Ants communicate
by sight and smell (Shutler 1991), and have no
effective method of communication with which
to coordinate their trail-clearing efforts. Their
solution to this disharmony is to break the ob-
stacle into smaller pieces, at which point their
random movements can effectively cart off the
objects.
Atta colombica ants were consistently cutting
leaf over 12 cm long (Fig. 4). In addition to
reducing the weight of the obstacle, this action
also pared down the leaf shape to make the
load less cumbersome. Ants have difficulty
balancing carried loads properly (Wirth et al.
2003) so this cutting may help sculpt the obsta-
cle into an easier-to-balance shape. I did not
record the presence of “spine-breaking” behav-
ior in my notes, but this phenomenon was a
major component of large object removal strat-
egy. “Spine-breaking” is the cutting of leaf
obstacles all the way through the leaf midrib,
cutting the leaf in two. In addition to lessening
the weight of the load and shaping the obstacle
to be better balanced, spine-breaking also re-
duces the distance between ants involved in the
object’s removal. This increased proximity may
allow the trail-clearers to visually identify each
other, and may even allow them to coordinate
the direction they pull. This spine-breaking
was only present in extremely large leaves (18-
24cm), but happened consistently through this
obstacle group.
It is certainly possible, though, that this
spine-breaking doesn’t allow for increased ant
communication. Instead, it may facilitate large
obstacle removal simply by reducing the num-
ber of ants needed to pull on each sub-object.
Fewer ants making random removal direction
choices would increase the likelihood that they
drag in the same direction.
My sample size (N= 104) in this study did
not show any significant difference in rates
between forests, or between the morning and
afternoon time periods (Table 1). However, a
more comprehensive analysis may reveal dif-
ferences. Pipeline Road, Parque Metropolitano,
and San Lorenzo forests had differing levels
of rainfall, elevation, and temperatures. A dis-
crepancy in rates could be attributed to this
rainfall gradient. Ants are highly susceptible
to desiccation (Wirth et al. 2003) and therefore
are attuned to water loss, which can be sub-
stantial even in humid rainforest conditions
(Brian 1977).
Foraging is affected by seasonal and diur-
nal variations in sunshine, temperature, hu-
midity, wind, and rainfall, in addition to mi-
croclimate variation due to weather and lo-
cal vegetation (Brian 1977). If studied more
closely, any of these factors may play a role
in controlling the rate of obstacle removal in
Atta colombica. Though the morning and af-
ternoon data sets showed no significant differ-
ence (Table 1), further study may reveal a dis-
crepancy. Forager slackness in the afternoon
has been seen in many species of ant (Brian
1977). Air temperature also affects ant move-
ment rates; Formica aqiulonia move 2.5 times
faster for every 10C rise (Brian 1969). Finally,
the moisture content and age of of leaves may
vary between forests and time periods. It takes
approximately 4x as long for foragers to cut
and harvest older leaves (Nichols-Orians and
Schultz 1989), which would also affect obstacle
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7. Tropical Ecology • February 2015 • Ecology and Evolutionary Biology
removal.
Further study will be necessary to test the
significance of these variables on any differ-
ence in removal rate between forests and time
periods. It would also be insightful to collect
data on spine-breaking behavior during these
future studies, as it may actually shed light on
ant communication strategies and group effort.
Trail-clearing and maintenance is an extremely
effective productivity-enhancing behavior in
Atta colombica, and may be responsible for their
success in the Neotropics. Maximizing removal
time is essential for maximizing obstacle re-
moval effort, but also may even limit predation
and parasitism on these colonies (Wirth et al.
2003).
V. Acknowledgments
I would like to thank Yves Basset, Ioanna
Chiver, and Paula Gomez for their invaluable
guidance during this amazing course, in ad-
dition to my research partners Jen Zhou and
Rachel Updike. I would also like to thank the
ants.
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