Diurnal, seasonal and annual variation in net ecosystem CO2 exchange of an alpine shrubland on Qinghai‐Tibetan plateau

作者：Liang Zhao, Yingnian Li, Shixiao Xu, Huakun Zhou, Song Gu, Guirui Yu, Xinquan Zhao · 发表于：Global Change Biology · 年份：2006 · DOI：10.1111/j.1365-2486.2006.01197.x · 被引用次数：201 · 研究领域：Plant Water Relations and Carbon Dynamics、Climate variability and models、Tree-ring climate responses

Abstract Thus far, grassland ecosystem research has mainly been focused on low‐lying grassland areas, whereas research on high‐altitude grassland areas, especially on the carbon budget of remote areas like the Qinghai‐Tibetan plateau is insufficient. To address this issue, flux of CO2 were measured over an alpine shrubland ecosystem (37°36′N, 101°18′E; 325 above sea level [a. s. l.]) on the Qinghai‐Tibetan Plateau, China, for 2 years (2003 and 2004) with the eddy covariance method. The vegetation is dominated by formation Potentilla fruticosa L. The soil is Mol–Cryic Cambisols. To interpret the biotic and abiotic factors that modulate CO2 flux over the course of a year we decomposed net ecosystem CO2 exchange (NEE) into its constituent components, and ecosystem respiration (Reco). Results showed that seasonal trends of annual total biomass and NEE followed closely the change in leaf area index. Integrated NEE were −58.5 and −75.5 g C m−2, respectively, for the 2003 and 2004 years. Carbon uptake was mainly attributed from June, July, August, and September of the growing season. In July, NEE reached seasonal peaks of similar magnitude (4–5 g C m−2 day−1) each of the 2 years. Also, the integrated night‐time NEE reached comparable peak values (1.5–2 g C m−2 day−1) in the 2 years of study. Despite the large difference in time between carbon uptake and release (carbon uptake time < release time), the alpine shrubland was carbon sink. This is probably because the ecosystem respirati...