Plant community responses to warming modified by soil moisture in the Tibetan Plateau

Abstract

Predicted warming in Tibetan Plateau may have profound effects on plant community structure and function. We used open-top chambers to artificially warm two different plant communities in Tibet from 2012 to 2016. We recorded species richness, vegetation height, and graminoid, forb, legume, and litter cover each year of the experiment and leaf growth and chemical traits of the most dominant species after four years of warming. Our results showed that vegetation height increased under warming in both the alpine meadow and the swamp. Warming also marginally increased legume cover and C:N ratio of all species in the alpine meadow but not in the swamp, suggesting that plant growth rate and nitrogen cycling are higher in the meadow in a warmer future. An observed tradeoff between water use efficiency and nitrogen use efficiency in the alpine meadow, but not in the swamp, also indicated that resource use may be more efficient in plants in the drier meadow under future warming. Overall, our results support predictions that soil moisture may modify plant community responses to climate warming and that changes in carbon and nutrient cycling may be more pronounced in drier alpine meadows than in wetter swamps under climate warming.

Keywords

• open-top chamber
• plant functional traits
• n use efficiency
• water use efficiency
• alpine meadow
• alpine swamp