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Predicting diversity of large herbivores from moisture and nutrient availability

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.

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Predicting diversity of large herbivores from moisture and nutrient availability

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  1. 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 21.09.2014 Predicting diversity of large herbivores from moisture and nutrient availability 1

  2. 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

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

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

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

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

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

  8. Hypotheses • Increasingmoisture→ larger herbivores Lessmoisture + increasingnutrientavailability→ smallerherbivores • Increasingnutrientavailability + intermediate moisture→ increasingspeciesdiversity Predicting diversity of large herbivores from moisture and nutrient availability

  9. 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) 21.09.2014 Predicting diversity of large herbivores from moisture and nutrient availability 9

  10. 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 21.09.2014 10

  11. Model Construction – Species Richness Herbivores diversity is higher at sites with intermediate plant-available moisture levels and increases with plant-available nutrients 21.09.2014 Predicting diversity of large herbivores from moisture and nutrient availability 11

  12. 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). 21.09.2014 Predicting diversity of large herbivores from moisture and nutrient availability 12

  13. Predictions on a global scale At global scale predicted regions seem to correspond to areas considered as diverse for this herbivores groups. 21.09.2014 Predicting diversity of large herbivores from moisture and nutrient availability 13

  14. 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. 21.09.2014 Predicting diversity of large herbivores from moisture and nutrient availability 14

  15. 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. 21.09.2014 Predicting diversity of large herbivores from moisture and nutrient availability 15

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