Temporal changes of vegetation water use efficiency and its influencing factors in Northern China

Abstract

Aims Water use efficiency (WUE) is an important variable for evaluating the growth adaptation of vegetation; it links carbon and water cycles of terrestrial ecosystems. Charactering the spatial and temporal variations in WUE and the driving factors not only can help understand the processes and regulations of ecosystem carbon and water cycles, but also provides scientific basis for formulating sustainable regional development policies and guiding water resources management. This study was conducted to determine the patterns of temporal changes for different vegetation types in northern China. Methods Flux and meteorological data of nine field observation sites in northern China were used to analyze the changes of WUE under different temporal scales, including half-hourly, daily, 8-day intervals, and monthly. The effects of temperature (T a), relative humidity (RH), vapor pressure deficit (VPD) and photosynthetically active radiation (PAR) on WUE under different time scales were also examined. Important findings (1) Diurnal change of WUE displayed an asymmetric "U" shape, with greater values at the sunrise than at the sunset. The seasonality of WUE in the Gobi and desert areas displayed a pattern of "U" shape, while it occurred as a single peak in other regions. The seasonal changes of WUE can be further divided into the

Spatial and temporal variations of vegetation water use efficiency and its response to climate change and human activities in the West Liao River Plain, China

“…The average WUE values of the different vegetation types ranked in the order of forest, cropland, grassland, wetland, shrubland, and bareland, respectively, were in general agreement with the results of previous studies (Feng et al, 2018;Chang et al, 2021). Although the WUE values followed the same order rule, the same land-use type showed different WUE values in different regions, which is consistent with the conclusions of other researchers (Liu et al, 2015;Muhammad et al, 2018).…”

Environmental Factors at Different Canopy Heights Had Significant Effects on Leaf Water-Use Efficiency in Cold-Temperate Larch Forest

“…Our study showed that VPD was the main factor affecting the WUE s of leaves in a larch forest at different canopy heights, which was similar to the results of Zhou et al [56] and Feng et al [57]. This can be explained by the fact that the fewer short-term changes in LAI, the relative stability of the ratio of transpiration (Tr) to ET [46] and changes in VPD directly affect changes in Gs that in turn affect WUE s [23].…”