Plant cover responses to simulated climate change in alpine plant species

Background/Question/Methods

A future upward migration of subalpine and alpine plant species has been predicted in response to climate change. Previous warming experiments have focused on temperature as the factor limiting plant range shifts. However, water stress on alpine plants in areas where precipitation during growing seasons is low may be a critical factor in determining how species will respond to year-round increases in temperature. Local distribution of plants in alpine systems is largely determined by moisture during the growing season. This study aims to determine if and how climate change will affect alpine plant species within their current restricted range, focusing on changes in cover to predict which species are likely to respond negatively to warming and which are likely to respond positively. As part of the Alpine-Treeline Warming Experiment at the Niwot Ridge LTER in Colorado, research tested the responses of plant species to warming and watering treatments over three growing seasons.  

Results/Conclusions

Interannual variability in total vegetation cover dominated any treatment effect, but species-level responses were observed after only one year of treatment.  The responses were gradual and became more pronounced during the most recent growing season. Continued warming and watering will likely result in changes from a greater number of species, as well as more dramatic responses as community structure shifts. Changes in plant cover of alpine species can be used to help predict which species will likely decline or disappear in response to warming. Changes in community composition may mean rare or drought-susceptible species will have a difficult time adapting to treatments and, as a result, limit energy allocation in producing aboveground biomass.