Plant community responses to five years of simulated climate warming in an alpine fen of the Qinghai-Tibetan Plateau

Background: Alpine and arctic ecosystems at high latitudes have been shown to be particularly vulnerable to climate change, but little has been reported about plant community responses from lower latitudes, such as the vast Qinghai-Tibetan Plateau. Aim: To examine how alpine fen plant community species richness, diversity, cover, above- and below-ground biomass, and how the abundance of two sedges, the dominant Kobresia tibetica and the subordinate Carex moorcroftii, respond to experimental warming. Methods: We used open-top chambers of two heights, with identical open-top area, to simulate two levels of experimental warming at 4700m on the Qinghai-Tibetan Plateau. Results: Five years of experimental warming reduced species richness and diversity, primarily due to a decrease in the diversity of graminoids. Above-ground biomass, vegetation height and cover increased at both levels of warming. Below-ground biomass increased at a depth of 5-20cm, but not at 0-5cm, indicating an allocation of resource to plant roots in deeper soils. Conclusion: The different responses to warming between the two graminoids in the study suggest that further studies on species-specific responses are needed to understand the regional differences observed in response to long-term warming. Our study also documented a decline in species richness and diversity in the control plots during the five-year experimental period which, together with results from other studies in this region, suggests that the alpine fens are already changing in response to the on-going climate warming in this area.