Compensatory responses to loss of warming-sensitive plant species.

Climate warming-induced plant species loss is likely to be nonrandom and based on species-specific susceptibility to changing climate. We examined the ecological consequences of losing shallow-rooted forbs, a group of species we predict to be adversely affected by climate change based on their response to experimental warming. After three years of experimental species removal, tap-rooted forbs and grasses were able to fully compensate for the loss of shallow-rooted forbs with increased biomass production. Moreover, the remaining plant community yielded a larger biomass response to nitrogen addition when shallow-rooted forbs were removed, possibly because removal led to increased soil moisture. We conclude that, although shallow-rooted forbs share a common response to warming, their loss did not affect community-level biomass. However, the loss of shallow-rooted forbs could result in increased sensitivity to perturbations, such as changing nutrient availability. Our results demonstrate that realistic, nonrandom scenarios of species loss do not necessarily follow the general pattern of decreased productivity and dampened response to nitrogen addition with species loss that is predicted by theory and many experimental results. Further examinations of nonrandom species loss in other ecosystems are needed to further improve our understanding of the consequences of human-driven species loss.