Abstract
Abstract. Water use efficiency is known as an important indicator of carbon and water cycle and reflects the transformation capacity of vegetation water and nutrients into biomass. In this study, we presented a new indicator of water use efficiency, soil water use level (SWUL), derived from satellite remote sensing based gross primary production and the Visible and Shortwave Infrared Drought Index (VSDI). SWUL based on MODIS data was calculated for the growing season of 2014 in Northeast China, and the spatial pattern and the variation trend were analyzed. Results showed that the highest SWUL was observed in forestland with the value of 36.65. In cropland and grassland, the average SWUL were 26.18 and 29.29, respectively. SWUL showed an increased trend in the first half period of the growing season and peaked around the 200th day. After the 220th day, SWUL presented a decreasing trend. Compared to the soil water use efficiency (SWUE), SWUL might depict the water use status at finer spatial resolution. The new indicator SWUL can help promote understanding the water use efficiency for regions of higher spatial heterogeneity.
Highlights
Ecosystem water use efficiency, the ratio of carbon assimilation to water loss, plays an important role in carbon and water cycles(Huang et al, 2017; Li et al, 2015)
Another ecosystem water use efficiency, namely, rain use efficiency (RUE), which is defined as the ratio of above net primary production (ANPP) to precipitation, can help us understand the coupling between the carbon and water cycles (Huang et al, 2016; Varnamkhasti et al, 2010)
We propose a new measure of Water use efficiency (WUE), soil water use level (SWUL), computed as the ratio of gross primary productivity (GPP) to Visible and Shortwave Infrared Drought Index (VSDI) and evaluate its application at a regional scale, taking the Northeast China as an example
Summary
The ratio of carbon assimilation to water loss, plays an important role in carbon and water cycles(Huang et al, 2017; Li et al, 2015). Water use efficiency (WUE; GPP/ET) is a significant physiological variable and measures the tradeoff carbon gain and water loss (Kørup et al, 2018; Lu et al, 2010; Xiao et al, 2013). WUE provides the information on the ecological process and hydrological process as well (Kwon et al, 2018; Xue et al, 2015). Another ecosystem water use efficiency, namely, rain use efficiency (RUE), which is defined as the ratio of above net primary production (ANPP) to precipitation, can help us understand the coupling between the carbon and water cycles (Huang et al, 2016; Varnamkhasti et al, 2010). VSDI is regarded as an effective indicator of soil moisture for different surface types (Zhang et al, 2013a; Zhang et al, 2013b)
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