Regulation of community and ecosystem dynamics by large tropical forest herbivores

Abstract

Large mammalian herbivores play a critical role in structuring ecosystems and regulating key ecosystem functions. Yet, whilst for grassland ecosystems this role is well established, for tropical forest species much of this role remains obscure. Here we propose to experimentally test how large tropical herbivores regulate nutrient cycling, soil fertility and the dynamics of plant communities. We will draw from data on soil nutrients and soil structure, nitrogen cycling and a plant seedling dataset with >8000 records collected at one of the largest long-term large herbivore exclusion experiment in the Neotropics, which has been running for more than 10 years in the Atlantic Forest of Brazil - BIOTA FAPESP Project 2014/0196-0. We will statistically test how nitrogen cycling, soil fertility and the dynamics of plant communities are affected by experimental defaunation. In doing so, we will address how large herbivore regulation of such processes changes across environmental gradients and availability of key resources, so as to disentangle the main axes of spatial variation in the dynamics of the system. We will take this empirical evidence further and build theoretical meta-ecosystem models to synthesise the influence of defaunation on the dynamics of critical ecosystem functions. (AU)