Stable isotopes reveal varying water sources of Caragana

作者：Hai Zhou,WenZhi Zhao,ZhiBin He,Heng Ren

摘要：Understanding the variation in a plant's water sources is critical to understanding hydrological processes in water-limitedenvironments.Here,we measured the stable-isotope ratios(δ18O)of xylem water of Caragana microphylla,precipitation,soil water from different depths,and groundwater to quantitatively analyze the proportion of water sources for the shrub.We found that the water sources of C.microphylla differed with the plant's ages and the seasons.The main water sourcefor young shrubs was upper-soil water,and it showed significant changes with seasonal precipitation inputs.In summer,the proportion contributed by shallow water was significantly increased with increased precipitation inputs.Then,the contributionfrom shallow-soil water decreased with the decline in precipitation input in spring and autumn.However,theadult shrubs resorted to deep-soil layers and groundwater as the main water sources during the whole growing season andshowed much less seasonal variation.We conclude that the main water source of the young shrubs was upper-soil waterand was controlled by precipitation inputs.However,once the shrub gradually grew up and the roots reached sufficientdepth,the main water sources change from the upper-soil layer recharged by precipitation to deep-soil water and groundwater,which were relatively stable and abundant in the desert ecosystem.These results also suggest that desert shrubs maybe able to switch their main water sources to deep and reliable water sources as their age increases,and this adjustment towater availability carries significant importance for their acclimation to the desert habitat.

发文机构：Linze Inland River Basin Research Station Lanzhou Information Center

关键词：WATER-USEpatternoxygenstableISOTOPEwatersourcesCARAGANAmicrophylla

分类号： P[天文地球]