Canopy transpiration and stand water balance between two contrasting hydrological years in three typical shrub communities on the semiarid Loess Plateau of China.
Understanding the role of canopy transpiration (Tr) in restoring vegetation's water balance is crucial for sustainable water management in semiarid regions. We examined the influencing factors of Tr and quantified stand water balance of three typical shrub species used for ecological restoration on the Loess Plateau of China in two contrasting hydrological years. This study included two native species, Vitex negundo (VN) and Spiraea pubescens (SP), and one introduced species, Hippophae rhamnoides. The experiment was conducted in two consecutive primary growing seasons in 2015 and 2016, during which the annual precipitation (P) was 41.5% and 102% of the long-term mean. The results showed that meteorological factors influenced the daily Tr primarily, and monthly Tr was mainly correlated with soil water content (SWC) in both the drier and wetter years. However, SWC's effect on Tr was more significant in the drier year. The sums of Tr and soil evaporation were significant in the three communities and accounted for 45.28-99.46% and 17.70-51.36% of the P in the drier year and wetter year, respectively. The changes in net soil water storage (ΔSW, 0-200 cm) were negative in most months in both years, with the greatest ΔSW decrease in VN in July 2015 and the greatest increase in SP in July 2016. Because of its different physiological characteristics, the introduced species maintained a relatively high Tr even in the drier year. Our results indicate that plant Tr and stand water balance should be considered in water-limited areas to promote ecologically sustainable management.