predicting diversity of large herbivores from moisture and nutrient availability

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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 04.07.22 1 Predicting diversity of large herbivores from moisture and nutrient availability

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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 Presentation

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Page 1: Predicting diversity of large herbivores from moisture and nutrient availability

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

Page 2: 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?

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Page 3: Predicting diversity of large herbivores from moisture and nutrient availability

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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Page 4: Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (1)

Plant productivity and quality change across environmental gradients

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Page 5: Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (2)

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Page 6: Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (3)

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Page 7: Predicting diversity of large herbivores from moisture and nutrient availability

Model theory (4)

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Page 8: 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

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Page 9: 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)

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Page 10: 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.

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Page 11: 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

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Page 12: 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 (R2=0.63, p=0.003, n=10).

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Page 13: 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.

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Page 14: 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 2025.

The study of these factors could help in spotting potential areas for the conservation of herbivore species.

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Page 15: 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.

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