Browsing by Subject "water use efficiency"

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    Enhanced coupling of light use efficiency and water use efficiency in arid and semi-arid environments
    (Wiley, 2021) Gao, Dexin; Wang, Shuai; Wang, Lixin; Li, Zidong; Pan, Ning; Liu, Yanxu; Fu, Bojie; Earth Sciences, School of Science
    Both light use efficiency (LUE) and water use efficiency (WUE) play essential roles in ecosystem production. The extent to which ecosystem production is affected by the coupling between LUE and WUE remains unclear. In this study, we used data from flux measurements and weather stations in the Heihe River Basin, China, along a strong climatic gradient to quantify the relationship between LUE and WUE. Variations of LUE explained up to 85% of the variations of WUE. The contribution of LUE to WUE increased with increasing water stress. Pearson’s correlation coefficient between LUE and WUE increased from −0.12 to +0.63 with decreasing LUE. The coordination between LUE and WUE was essential to explaining the insensitive of WUE and GPP with increasing water stress. These results suggest that ecosystems enhance the coordination between light and water use when water stress is high. They enhance our understanding of the drought resilience of ecosystems and reduce uncertainties associated with the carbon cycle in drylands.
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    Water use characteristics of the common tree species in different plantation types in the Loess Plateau of China
    (Elsevier, 2020-07) Wang, Jian; Fu, Bojie; Wang, Lixin; Lu, Nan; Li, Jianye; Earth Sciences, School of Science
    Knowledge concerning the water use characteristics of revegetated species has profound implications for understanding soil–plant interaction mechanisms and guiding ecological restoration strategies in water-limited ecosystems. Although afforestation is an important way to improve ecosystem functions and services in degraded ecosystems, there is limited understanding about the water use characteristics of dominant species within and between different types of plantations. We investigated plant water use characteristics in three representative types of plantations on the Chinese Loess Plateau: mixed plantation consisting of three deciduous tree species Robinia pseudoacacia, Armeniaca sibirica and Ailanthus altissima (Mspa), pure R. pseudoacacia plantation (Pp) and pure A. sibirica plantation (Ps). We measured the leaf δ13C of the dominant species within each plantation type and the δ2H and δ18O of xylem and soil water within 400 cm of the soil surface. The results showed that three main species in the mixed plantation exhibited significant difference (p < 0.05) in proportional contributions of water sources, suggesting that the plants had water source segregation. A. sibirica in the mixed plantation utilized more proportional shallow soil water than that in the pure plantation and correspondingly lessened deep soil water depletion. However, no significant difference was found in the water uptake proportions of R. pseudoacacia between the different plantation types. The leaf δ13C values of the plant species in the mixed plantation were significantly higher than those in the pure plantations. The leaf δ13C values of R. pseudoacacia under different plantation were positively associated with SWCs, but this relationship was not observed in A. sibirica. These results indicate that plantation type affected plant water use characteristics with species-specific responses to plantation type and different water source competition effects between interspecific versus intraspecific competition.