Top-down effects of predators on soil food web could buffer carbon losses in a warmer Arctic

Background/Question/Methods

Predator-induced trophic cascades have been shown to impact both community structure and ecosystem processes, yet it is unclear how climate change may exacerbate or dampen predator effects on ecosystems. Understanding the potential of predators to drive ecosystem processes and how this might be altered by climate change is especially relevant in the Arctic, a region which stores more than a third of the world’s terrestrial carbon and is experiencing some of the greatest rates of climatic warming. Through a field experiment manipulating temperature and spider density in the arctic tundra, we examined the influence of the dominant predator, wolf spiders, on the structure of soil microarthropod communities and decomposition rates. 

Results/Conclusions

We find that predator effects on soil microarthropods change in response to warming and that these changes translate into context-specific indirect effects of predators on decomposition. Specifically, while high densities of wolf spiders lead to faster decomposition rates at ambient temperatures, they are associated with slower decomposition rates in experimentally warmed plots. Our results suggest that if warming causes an increase in arctic wolf spider densities as predicted, these spiders may buffer the rate at which the massive pool of stored carbon is lost from the tundra. These findings improve our understanding of how climate change-induced effects on predators can cascade through other trophic levels, altering critical ecosystem functions, and leading to climate feedbacks with important global implications.