Carbon fluxes, evapotranspiration, and water use efficiency of terrestrial ecosystems in China
The magnitude, spatial patterns, and controlling factors of the carbon and water fluxes of terrestrial ecosystems in China are not well understood due to the lack of ecosystem-level flux observations. We synthesized flux and micrometeorological observations from 22 eddy covariance flux sites across China,and examined the carbon fluxes, evapotranspiration (ET), and water use efficiency (WUE) of terrestrial ecosystems at the annual scale. Our results show that annual carbon and water fluxes exhibited clear latitudinal patterns across sites. Both annual gross primary productivity (GPP) and ecosystem respiration (ER) declined with increasing latitude, leading to a declining pattern in net ecosystem productivity (NEP) with increasing latitude. Annual ET also generally declined with increasing latitude. The spatial patterns of annual carbon and water fluxes were mainly driven by annual temperature, precipitation, and growing season length. Carbon fluxes, ET, and water use efficiency (WUE) varied with vegetation type. Overall,forest and cropland sites had higher annual fluxes than grassland sites, and the annual fluxes of coastal wetland sites were similar to or slightly higher than those of forest sites. Annual WUE was associated with annual precipitation, GPP, and growing season length. Higher-productivity ecosystems (forests and coastal wetlands) also had higher WUE than lower-productivity ecosystems (grasslands and croplands). The strong relationships between annual GPP and ET demonstrated the coupling of the carbon and water cycles. Our results show that forest plantations had high annual NEP and WUE, and could provide larger carbon sequestration capacity than natural forests. The coastal salt marsh and mangrove ecosystems also had high carbon sequestration capacity. Efforts to strengthen China’s terrestrial carbon sink should focus on ecosystems such as forest plantations in southern China where heat and water are ideal for maintaining high productivity. This strategy is especially important because efforts to increase carbon sequestration in areas of limited water may inadvertently contribute to the ongoing water crisis in northern China.
You can order print copies of our publications through our publication ordering system. Make a note of the publication you wish to request, and visit our Publication Order Site.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unuseable.
- To view this article, download the latest version of Adobe Acrobat Reader.