the risk of land degradation is greatest in the median section of the aridity gradient (mostly the semiarid drylands), where both sensitivity to degradation and population pressure (expressed by population density) are of intermediate values.Para avaliar a eficácia da convenção na área da sustentabilidade, da gestão dos solos e da gestão dos ecossistemas;UN criou um processo de monitorização e avaliação;Adoptou 11 indicadores de impacte em 11 países entre os quais PT
Theoretically, rates of ecosystem processes might increase linearly with species richness if all species contribute substantially and in unique ways to a given process — that is, have complementary niches. However, when different species have similar functions at the ecosystem level this relationship is likely to saturate as niche overlap and ‘redundancy’ increases at higher levels of diversity. enabling to evaluate vegetation response both in the form of species turnover, shifts in abundance and/or morpho-functional traits
These traits relate to resource acquisition and retention, decomposition and stress avoidance/tolerance
Flat biomass , isotopic composition, N and C leaf
Cristina BRANQUINHO "Searching for universal early-warning indicators of desertification: anticipating tipping points at ecosystem level"
“Searching for universal early-warningindicators of desertification: anticipating tipping points at ecosystem level ” Cristina Branquinho1, Pedro Pinho1,2, Alice Nunes1,3, Paula Matos1,3, Melanie Batista1, Adriana Silva1, Andreia Ferreira1 and Lúcio do Rosário41Universidade de Lisboa;2Universidade Técnica de Lisboa;3Universidade de Aveiro; Ciência 20074Instituto de Conservação da Natureza e Florestas; LTER/BIA-BEC/0048/2009 PTDC/AAC-CLI/104913/2008
Drylands • Cover about 41% of Earth’s land surface supporting over 38% of the global human population • Semi-arid areas are the most vulnerable to DLDMillennium Ecosystem Assessment (2005) Ecosystems and Human Well-Being: Desertification Synthesis (World ResourcesInstitute, Washington, DC).
Mechanisms of transitions between ecosystems states and tipping points An ecosystem experiences a shift to a new state, with significant changes to biodiversity and the services to people it underpins, at a regional or global scale. Tipping points also have at least 1 of the following characteristics: ✤ The change becomes self perpetuating (deforestation reduces regional rainfall, which increases fire-risk, which causes forest dieback and further drying). ✤ There is a threshold beyond which an abrupt shift of ecological states occurs. ✤ The changes are long-early warning lasting and hard to reverse. ✤ There is a significant time lag between the pressures and the appearance of impacts.Secretariat of the Convention on Biological Diversity (2010) Global Biodiversity Outlook 3.
Ecosystem functioning is extremely complex and thus monitoring the effects ofenvironmental change factors in ecosystems in an integrative perspective canmake use of ecological indicators.
Hypothesis/Assumptions• It is possible to find early warning indicators of tipping points.• Those indicators are most probably ecological indicators which reflect in overall an integrated response of the ecosystem.• Indicators based on biodiversity changes can be one of those indicators.• Without time we can use gradients in space to give us a clue about possible good indicators.
Does all species have the same value? Ecosystem Processes BiodiversityM. Scherer-Lorenzen, (2005), BIODIVERSITY AND ECOSYSTEM FUNCTIONING: BASIC PRINCIPLES, in Biodiversity: Structure and Function, [Eds. WilhelmBarthlott, K. Eduard Linsenmair, and Stefan Porembski], in Encyclopedia of Life Support Systems (EOLSS),, Oxford ,UK
Functional Diversity – Potentially Universal Functional diversity: groups according to common response to the environment and/or common effects on ecosystem processes/functions • Has been shown to relate with several environmental constraints (e.g. nutrient availability, grazing, fire, etc.) • • Independent from local communities composition - potential to be universalDíaz, S. & Cabido, M. (2001) Trends in Ecology & Evolution 16, 646-655.Lavorel, S. et al. (2007) Plant Functional Types: Are We Getting Any Closer to the Holy Grail? Springer-Verlag, Berlin Heidelberg. pp.149-160.
Study site Portugal susceptibility to DLD Aridity Index sub-humid and humid dry sub-humid semi-arid Mediterranean climate with Montado, an agro-pastoral system dominated by holm-oak (Quercus ilex L.) woodlands Study transition in a spatial aridity gradientSource: Autoridade Florestal Nacional
Selection of the DLD gradient Homogeneous conditions Stratified sampling (precipitation, (Holm-oak open woodlands, grazing temperature, aridity indices, etc.) intensity, lithology, slope, fire occurence, etc.) precipitation soil organic C Aridity Evapotransp. Susceptibility Temperature aRandom selection of sites (≥60)
establishing relation between climate and biological variables 1) Lanscape scale – remote sensing analysis 2) Using plant Functional diversity 3) Using lichen Functional diversitydesertification and land-degradation gradient
vegetation structure1) Landscape - Canopy Cover Dry Frequency Intermediate Wet Canopy Area
2) Using Plant functional diversity Legum. Non legum. • Point-line intercept transect method • A priori functional groups (e.g. life cycle, life form, etc.) and measured traits (e.g. SLW, height, etc.)
2) Using Plant functional diversity 24 sites analyzed Plant functional shifts 80 Functional groups cover 60 Annual graminoids + Plantago sp. (%) 40 Perennial graminoids + 20 Annual N- fixing 0 500 550 600 650 Last 50 Years average precipitation (mm)
2) Using Plant functional traits 14 sites analyzed 40 SLA T. barbata (m2kg-1) 30 20 10 0 Measured only for 2 species 500 525 550 575 600 625 650 Last 50 yr precipitation (mm) 25 Veg. height V. myurus (Q90) 20 15 10 5 0 0.4 0.5 0.6 0.7 0.8 Aridity index Measured for all species
3) Using lichen Functional diversity Standard “European method” L DV (lichen diversity value)Asta, J., et al, 2002. Monitoring with Lichens, Kluwer Academic Publisher.
3) Using lichen Functional diversity lichens functional diversity as early warning of desertification Hygrophytes Xerophytes annual average precipitation (mm)
3) Using lichen Functional diversity Does lichen diversity respond to climate over time? Before: 2002 After: 2003
nal Remarks Functional diversity (plants and Lichens) seems to be a good candidate for early warning since it respond to changes in climate and desertification gradients. Moreover has the potential to be universal. We are contributing to the 3 UN "sister Conventions": on biodiversity-CBD, climate change-UNFCCC and desertification-CDD, that relay in ecological indicators of biodiversity and ecosystem goods and services evaluation. We are willing to test this hypothesis in other countries. Thank You!