Response of Alpine Plants to Nitrogen Addition on the Tibetan Plateau: A Meta-analysis

Abstract

To identify the general effects of nitrogen addition on alpine plants, we used a meta-analysis approach to synthesize 599 observations from 51 studies on the Tibetan Plateau. Nitrogen addition significantly increased plant height by 19.0 %, plant biomass by 29.7 %, graminoid aboveground biomass by 89.8 %, and sedge aboveground biomass by 75.6 % but significantly decreased legume aboveground biomass by 34.5 %, forb aboveground biomass by 23.8 %, and species richness by 11.2 %. The effect of nitrogen addition on aboveground plant biomass and plant height increased with increasing the nitrogen addition rate. The effect of nitrogen addition on plant height increased with increasing mean annual precipitation but decreased with increasing mean annual temperature. Our findings suggested that the effect of nitrogen addition on alpine plants varied with plant functional types and nitrogen addition rate. In addition, climatic warming and precipitation changes may regulate the response of alpine plants to nitrogen addition on the Tibetan Plateau.