More portion of precipitation into soil water storage to maintain higher evapotranspiration induced by revegetation on China’s Loess Plateau

Abstract

Revegetation of degraded ecosystems provides opportunities for improving ecosystem production, mitigating climate change, and improving carbon sequestration. Revegetation tends to reduce streamflow (Q) caused by enhanced evapotranspiration (ET) or increase the water yield (W) due to increasing soil water infiltration with the steady state assumption, while under multiple steady states, its effects on the hydrological state remain controversial. Here, the assumptions that ET is calculated from water balance (ETwb) and using evaporation theory (ETc) are independent. Assessment of the hydrological states can be provided following this assumption in a water-limited region, such as the Loess Plateau, China. The results showed that: (i) revegetation dramatically improved the leaf area index (LAI) over the Loess Plateau, and abrupt LAI changes were detected in 2002; (ii) enhanced ET (ETwb and ETc) with revegetation was observed, and the elevated fraction of precipitation (P) partitioned into ETwb led to decreases in W (P-ETc); and (iii) as inferred by our assumption, most catchments tended to be wetter (11 among 17 catchments), which indicates that soil water storage (SWS) also increased combined with increased ET and decreased Q. Our results provide new insight into revegetation playing a new role in partitioning P into ET, Q and SWS. Higher ratios of P tend to be intercepted in SWS to maintain higher ET and even induce a reduction in Q in most regions of the Loess Plateau, China.