Impacts of terrestrial mammalian herbivores on vegetation change in the arctic.

There are increasing concerns about regional ecosystem shifts in the Arctic due to climate change. Notably, warming-induced increases in Arctic vegetation cover can have important consequences for surface energy balance, habitat changes, permafrost, and more. Mammalian herbivory is an important potential force to counteract this effect. In this systematic literature review, we examine the role of terrestrial mammalian herbivory on warming-induced increases in Arctic vegetation. We analyse the effects of terrestrial mammalian herbivory on vegetation cover, abundance, growth, survival, and ecosystem productivity. Our results show that herbivory has an overall significant negative influence on Arctic vegetation, particularly on vegetation biomass, growth, and productivity, as indicated by the Normalised Difference Vegetation Index (NDVI). Importantly, we demonstrated a significant role of herbivores in controlling carbon dioxide exchange and carbon uptake, whilst acknowledging that the relationship between herbivory and ecosystem productivity is highly complex and site-dependent. Our results confirm the important role that herbivory can play in buffering observed and predicted warming-induced Arctic vegetation increases. We also find that this is strongly affected by plant palatability, trampling occurrence, and herbivore density. [ABSTRACT FROM AUTHOR]