Response of carbon- and water-use efficiency to climate change and human activities in China

Abstract

Carbon-use efficiency (CUE) and water-use efficiency (WUE) are critical parameters for evaluating the exchange of carbon and water in ecosystems, influenced by climate change and human activities. Quantifying the relative contributions of climate change and human activity to CUE and WUE is essential in the context of global warming and rapid land use transformation. This study assessed spatiotemporal variations in CUE and WUE and evaluated their interconnections with climate factors through comprehensive trend and partial correlation analyses. Furthermore, it explored the responses of CUE and WUE variations to climate change and human activities across distinct geographical zones in China from 2001 to 2019, employing multiple regression residual trend analysis. Our analysis suggested that annual average CUE was 0.57 and annual average WUE was 1.47 g C kg−1H2O. Spatially, CUE demonstrated an increase in northern China but a decline in the southern regions, while WUE exhibited a contrasting trend. Generally, CUE exhibited a positive correlation with increased precipitation (PRE) and solar radiation (RAD) but displayed a negative association with elevated air temperature (TEM). Conversely, WUE showed an increase with greater PRE and TEM but a decrease with heightened RAD. Notably, it was revealed that human activities exerted a more significant impact on CUE and WUE in China than climate change. However, climate change played an important role in some areas with low populations, such as the Qinghai–Tibet Plateau. The results will improve the understanding of the carbon and water coupled process in terrestrial ecosystems, which is helpful to optimize the allocation of ecological resources and maintain ecosystem balance.

Keywords

• Carbon-use efficiency
• Water-use efficiency
• Climate change
• Human activity
• Land use