Global classification of mammalian herbivores coupled with a mechanistic eco-physiological model for macro ecology and Earth System applications

Background/Question/Methods

Terrestrial mammalian herbivores (TMH) play a key role in ecosystem functioning and biogeochemical cycles. The ecosystemic role of heavy TMH has been widely discussed but much less is known about the role of thousands of lighter-bodied mammalian species. Regardless of body mass, the importance of TMH in the Earth System has likely been underestimated as they are not fully integrated in Earth System Science. We overcome this problem by developing the first global classification of TMH organized in 8 dietary macro-groups and further classified in 24 herbivore functional types. We employed this classification in a novel mechanistic eco-physiological land surface model which we called REMAP (REconstructing MAmmal Populations). By using REMAP we reconstructed present-day global patterns of herbivore biomass for each functional type under natural conditions (no hunting in natural habitat).

Results/Conclusions

Our results provide novel insights on the global patterns of herbivore biomass and its loss due to anthropogenic-driven land cover changes. We show that potential biomass hotspots coincide with areas of intense human activity and density. We also show that light mammals comprise more than 40% of the total herbivore biomass and they are more functionally diverse. These results have implications for mammal conservation, rewilding, and the refocusing of macro ecology to include also light mammals. Our classification of mammalian herbivores coupled with a mechanistic model opens new opportunities for integrating mammals and other animals in Earth System models.