predicting diversity of large herbivores from moisture and nutrient availability
DESCRIPTION
Predicting diversity of large herbivores from moisture and nutrient availability. b ased on the article of Olff et al. (2002): “Global environmental controls of diversity in large herbivores”. John Garcia and Corina Del Fabbro. 21.09.2014. - PowerPoint PPT PresentationTRANSCRIPT
Predicting diversity of large herbivores from moisture and nutrient availability
based on the article of Olff et al. (2002): “Global environmental controls of diversity in large herbivores”
John Garcia and Corina Del Fabbro
21.04.23 1Predicting diversity of large herbivores from moisture and nutrient availability
Introduction
Large mammalian herbivores are threatened
Large herbivores require great plant abundance whereas small herbivores require high nutrient content
Rainfall, soil fertility and primary productivity influence plant quality and herbivore community biomass
How do rainfall, soil fertility and primary productivity affect herbivore diversity?
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Outline
Theory and Hypotheses
Model Construction
Model Validation
Predictions on a global scale
Implications
ConclusionsKlipspringer (http://www.wildlife-pictures-online.com/image-files/klipspringer_rctb-6638.jpg)
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Model theory (1)
Plant productivity and quality change across environmental gradients
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Model theory (2)
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Model theory (3)
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Model theory (4)
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Hypotheses
Increasing moisture → larger herbivores
Less moisture + increasing nutrient availability → smaller herbivores
Increasing nutrient availability + intermediate moisture → increasing species diversity
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Methods
Compilation of occurrence and richness data of all terrestrial species of herbivores (mass > 2 kg)
33 sites in North America and 85 in sub-Saharan Africa
Elaboration of indices for plant-available Moisture and Nutrients
Species Richness is expressed as a proportion of the total species richness per continent (to standardize differences)
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Model Construction – Species level
Larger species peak at higher moisture levels. Larger species seem to be independent form plant-available
nutrients levels. Smaller species are more frequent at higher quality plants levels.
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Model Construction – Species Richness
Herbivores diversity is higher at sites with intermediate plant-available moisture levels and increases with plant-available nutrients
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Model Validation
Using the multiple regression model, areas with high diversity of large herbivores were predicted for 10 natural areas in Australia.
Results were compared to observed diversity.
Strong correspondence between predicted and observed areas (R2=0.63, p=0.003, n=10).
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Predictions on a global scale
At global scale predicted regions seem to correspond to areas considered as diverse for this herbivores groups.
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Implications
25% of the large herbivore species per continental pool can be hosted in less than 5% of land.
Less than 2% of the prime regions for large herbivore diversity overlap with regions designated as biodiversity hotspots.
Current land-use practices suggest that less than 1.2% of the earth's surface might remain to support uniquely diverse, grazing ecosystems by 2025.
The study of these factors could help in spotting potential areas for the conservation of herbivore species.
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Conclusions
Plant resources (Plant-available moisture and nutrients) constrain the distribution of large herbivores.
Plant-available moisture and nutrients predict patterns of large herbivores diversity
Authors suggest that this approach could be applied to other groups of organisms.
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