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 Predicting 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? Predicting diversity of large herbivores from moisture and nutrient availability

Outline  Theory and Hypotheses  Model Construction  Model Validation  Predictions on a global scale  Implications  Conclusions Klipspringer ( online.com/image-files/klipspringer_rctb-6638.jpg) Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (1)  Plant productivity and quality change across environmental gradients Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (2) Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (3) Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (4) Predicting diversity of large herbivores from moisture and nutrient availability

Hypotheses  Increasing moisture → larger herbivores Less moisture + increasing nutrient availability → smaller herbivores  Increasing nutrient availability + intermediate moisture → increasing species diversity Predicting diversity of large herbivores from moisture and nutrient availability

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) Predicting diversity of large herbivores from moisture and nutrient availability

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 Predicting diversity of large herbivores from moisture and nutrient availability

Model Construction – Species Richness  Herbivores diversity is higher at sites with intermediate plant-available moisture levels and increases with plant- available nutrients Predicting diversity of large herbivores from moisture and nutrient availability

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 (R 2 =0.63, p=0.003, n=10) Predicting diversity of large herbivores from moisture and nutrient availability

Predictions on a global scale  At global scale predicted regions seem to correspond to areas considered as diverse for this herbivores groups Predicting diversity of large herbivores from moisture and nutrient availability

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  The study of these factors could help in spotting potential areas for the conservation of herbivore species Predicting diversity of large herbivores from moisture and nutrient availability

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 Predicting diversity of large herbivores from moisture and nutrient availability