Increased Interception Induced by Vegetation Restoration Counters Ecosystem Carbon and Water Exchange Efficiency in China

Abstract

Because of the large carbon sequestration potential, vegetation restoration is among the most prominent natural climate solutions (Cerasolia et al., 2021). Earth is greening since the 1980s, with one of the largest contributions from China, which accounted for 25% of the global increase in vegetation (C. Chen et al., 2019). Large-scale vegetation restoration increases the extent of the canopy, which has an impact on evapotranspiration (ET) and on its partitioning (ET is the combination of canopy-intercepted water (Ei), soil evaporation (Eb), and transpiration (Et) from plants; Shao et al., 2019;. ET is one of the most important processes for ecosystem carbon and water exchange, and accurate quantification of ET partitioning is essential for investigating the influences of environment changes on carbon assimilation and water cycle change (Coenders-Gerrits et al., 2014;

Disentangling the Key Drivers of Ecosystem Water-Use Efficiency in China’s Subtropical Forests Using an Improved Remote-Sensing-Driven Analytical Model

“…This assumption may be unsuitable for the humid subtropical region because RH and precipitation are usually uncorrelated, particularly in a humid region such as China's subtropics, where the RH almost exceeds 70% during the year, but not necessarily with precipitation. Therefore, the original equation in the PT-JPL model may significantly overestimate the E i , as reported by previous studies [50,51], especially in subtropical regions of China, by up to three-fold [38,52]. Therefore, in this study, we adopted the modified Gash model [53,54] to replace the original equations in the PT-JPL model and calculate the E i .…”

“…However, the original analytical WUE model, as shown in Equation ( 6), is mainly determined by the five controlling factors, namely the C a , p a , VPD, L, and f Ei , especially the f Ei , calculated based on the published global E i and ET data sets in the original analytical WUE model [6]. Some key drivers, such as precipitation, temperature, net radiation (RN), VPD, and LAI, can also significantly affect E i and ET, thereby influence forest WUE [6,[37][38][39]. Therefore, ignoring these drivers may hinder our understanding of the real mechanisms of WUE changes when using the original analytical WUE model.…”

“…Recently, the analytical WUE model [6] was widely used to simulate and diagnose the driving mechanism of WUE changes [6,37,38]. The analytical WUE model has the advantages of a solid biophysical foundation and a simple model structure.…”

“…It requires few parameters and model inputs (e.g., only a few remote sensing data) [6,37,39]. Moreover, in contrast to the traditional ecosystem WUE model based on the ratio of GPP and ET [1,3,26], the analytical WUE model directly upscales WUE from the leaves to the ecosystem without pre-estimating GPP, thus tremendously reducing the uncertainty [6,38]. Therefore, this method has huge potential to simulate the subtropical forest WUE and investigate its mechanisms.…”

The response of geographical processes to landscape restoration: China’s research progress

“…These responses are experiential, which can be physically or measured, economically valued, subjectively scored, or even evaluated by manual designed indicators. Many physical responses from vegetation change are spatially explicit, for example: the increase in terrestrial carbon sink (Lu et al, 2022); the shrinkage of water yield (Wang et al, 2021b); the change in remote benefits from wind erosion prevention and water erosion prevention (Hu et al, 2022; Thomaz et al, 2022); the change in ecohydrological processes such as water use efficiency (Ding et al, 2021; Shao et al, 2022); the gain of nutrient removal by marsh vegetation near cultivated land (Liu et al, 2022a); and the promotion in microclimatic conditions by the hydrologic cycle from the surrounding landscape (Cheng et al, 2022; Peng et al, 2022a). The livelihood responses to landscape restoration are also spatiotemporally different.…”