Ecosystem Water Use Efficiency in the Three-North Region of China Based on Long-Term Satellite Data

Qi’Ao Zhang,Wei Chen

doi:10.3390/su13147977

Abstract

Water use efficiency (WUE), given by the ratio between organic matter production and water consumption, could be considered as a very important ecological indicator for assessing vegetation system growth conditions by combining organic matter production and water consumption. It is especially important for regional vegetation sustainable management by creating enough organic matter with restricted water supply. Furthermore, proper analysis of WUE is vital for the evaluation and future plans of ecological restoration projects in ecologically fragile regions such as the Three-North region of China. In this study, ecosystem WUE across the Three-North region of China from 2001 to 2017 was obtained, and the variation trends and major influencing factors were also analyzed. The results demonstrated that (1) the average WUE across the Three-North region of China is 0.7376 g∙C∙m−2∙mm−1 with an annual increase of 0.002 g∙C∙m−2∙mm−1∙y−1; (2) the spatiotemporal variation trends of WUE are similar to those of gross primary production (GPP); and (3) in the southeastern parts of the Three-North region, the vegetation conditions are better with sustainable improvements, while in Xinjiang Province, the sustainable degradation areas are widely spread. The results of this research reveal large spatial heterogeneity of WUE, with high WUE mainly in the southeastern region with sufficient precipitation and afforestation programs. For those areas far away from this region, WUE is not satisfactory, suggesting that, for a sustainable vegetation growth, it is important to consider the water supply to maintain suitable vegetation cover. Furthermore, the results of this research are important for future ecological restoration and sustainable management of environment.

Highlights

Vegetation plays an important role in terrestrial ecosystems by absorbing carbon dioxide and consuming water during photosynthesis [1]
We propose in this paper the use of an index based on the ratio of gross primary production (GPP) to evapotranspiration (ET) that could be calculated by remote sensing data and could be useful to characterize the different areas of a region in terms of water use efficiency [8,9,10]
water use efficiency (WUE) is an important ecosystem indicator reflecting the carbon–water cycle of vegetation cover, which is of much potential meaning for both ecological restoration and environmental management

Summary

Introduction

Vegetation plays an important role in terrestrial ecosystems by absorbing carbon dioxide and consuming water during photosynthesis [1]. The net radiation results are usually cooled with spatial diversities [4] Beyond these effects, vegetation can produce organic matter through primary production and affect the carbon balance, regulating regional and global climates [5]. Vegetation may utilize different amounts of water depending on its species composition. This aspect has to be considered with great attention in plans of reforestation. We think that for developing plans of restoration it would be very important to characterize the different areas of interest in terms of water use efficiency (WUE). We propose in this paper the use of an index based on the ratio of gross primary production (GPP) to evapotranspiration (ET) that could be calculated by remote sensing data and could be useful to characterize the different areas of a region in terms of water use efficiency [8,9,10]

Objectives

Methods

Results

Discussion

Conclusion