Field-based observations of regional-scale, temporal variation in net primary production in Tibetan alpine grasslands
- 1Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 5 Yiheyuan Rd., 100871 Beijing, China
- 2Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., 810008 Xining, China
- 3Department of Ecological Sciences, College of Life Sciences, Inner Mongolia University, 010021 Hohhot, China
- 4Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
Abstract. Net primary production (NPP) is a fundamental process of natural ecosystems. Temporal variation of NPP not only reflects how communities respond to environmental fluctuations, but it also has important implications for regional carbon assessment. Unfortunately, studies based on field measurements to directly address this issue in the extreme environment of alpine grasslands are rare. In this study, we measured aboveground NPP (ANPP) and species richness in 40 sites across the Tibetan alpine grasslands from 2006 to 2009 to investigate the regional pattern of temporal variation in ANPP and to quantify the effects of climate fluctuation and biodiversity on this variation. The results showed that, during the 4-year period, the average ANPP varied 1.5-fold, from 83.9 to 125.7 g m−2, with a mean coefficient of variation of temporal variation of 36.6% across the 40 sites. Compared with other studies, alpine grasslands are not more sensitive to climate fluctuations than other grassland types. Aboveground NPP exhibited synchronous temporal variation and consistent spatial patterns over the 4-year period due to the regionally similar climatic fluctuations caused by monsoon-dominated plateau climate. Surprisingly, rainfall fluctuation had a more profound effect on the ANPP dynamics than temperature variation, which suggests that production in the Tibetan alpine grasslands is primarily driven by precipitation. Therefore, ANPP in the Tibetan alpine grasslands are mainly constrained by water availability. Finally, we found a reduction in interannual variation (i.e., CV) in ANPP with increasing species richness of plant communities, suggesting that diversity can stabilize community production in high-altitude grasslands.