Can large herbivores enhance ecosystem carbon persistence?

There is growing interest in aligning the wildlife conservation and restoration agenda with climate change mitigation goals. However, the presence of large herbivores tends to reduce aboveground biomass in some open-canopy ecosystems, leading to the possibility that large herbivore restoration may negatively influence ecosystem carbon storage. Belowground carbon storage is often ignored in these systems, despite the wide recognition of soils as the largest actively-cycling terrestrial carbon pool. Here, we suggest a shift away from a main focus on vegetation carbon stocks, towards inclusion of whole ecosystem carbon persistence, in future assessments of large herbivore effects on long-term carbon storage. Failure to do so may lead to counterproductive biodiversity and climate impacts of land management actions. Grasslands are often overlooked global reservoirs of carbon, with soil carbon stocks large enough to compensate for the lower aboveground biomass carbon compared to forests. Due to a larger fraction of ecosystem carbon stored belowground, particularly in more persistent mineral-associated fractions, grazed grassland carbon stocks may be less vulnerable to perturbations than systems with higher aboveground carbon storage. To optimise restoration efforts to achieve both biodiversity and climate mitigation goals, we need to shift away from focusing only on building immediate carbon stocks to include carbon persistence. Herbivores can increase the persistence of ecosystem carbon through redistributing carbon from aboveground vegetation pools vulnerable to disturbances into persistent soil pools. This is particularly important in ancient fire-prone grasslands, but increasing disturbance frequencies across many ecosystems make herbivore restructuring of carbon pools relevant in a wider range of systems. [ABSTRACT FROM AUTHOR]