Response of water use strategies of Tamarix ramosissima to nebkhas accumulation process
Aims Tamarix ramosissima,as the main dominant plant species in arid deserts,has formed Tamarisk nebkhas during its long-term interaction with wind-sand.The study on water sources of T.ramosissima at nebkhas and its ratio to each water source can provide scientific basis for the conservation,restoration of native vegetation in arid desert areas.Methods This study employed"space for time"methodology to clarify the water sources of T.ramosissima at nebkhas,with the ratio of each water source quantified for T.ramosissima at different developmental stages of nebkhas,through field investigation and indoor model analysis.Important findings(1)The soil moisture of T.ramosissima nebkhas varied with the nebkhas accumulation process.The average soil moisture in the 0-500 cm soil depth ranked in the order of:the embryonic stage(4.57％)＞growth stage(4.46％)＞decline stage(3.62％)＞stable stage(3.48％).(2)The soil water content of the dunes increased significantly in the 40-180 cm layer during the embryonic and growth stages,and in the 180-360 and 360-500 cm layers during the stable and decline stages,respectively.(3)The soil water content and stable oxygen isotope ratio(δ18O)in the 0-40 cm layer of the nebkhas at each stage of development fluctuated significantly with seasonal changes,and the δ18O stabilized with increasing depth of the soil layer,indicating that the surface soil was influenced more by the external environment.(4)In spring,T.ramosissima mainly used the soil water in the 360-500 cm layer in the embryonic stage nebkhas,followed by the soil water in the 0-40 cm layer,with proportions of 53.1％ and 21.4％,respectively;in the growth stage nebkhas,T.ramosissima mainly used soil water in 0-40 and 360-500 cm layers,with ratios of 53.1％ and 23.0％,respectively;in the stable stage nebkhas,T.ramosissima mainly used soil water in 0-40 and 180-360 cm layers,with ratios of 49.8％ and 29.3％,respectively;in the decline stage nebkhas,T.ramosissima mainly used soil water in the 360-500 cm layer,with a ratio of 60.9％.In summer,T.ramosissima mainly used soil water in the 360-500 cm layer in the embryonic and growth stage nebkhas,and the ratio was 61.1％ and 42.8％,respectively.Tamarix ramosissima also used soil water in the 40-180 and 180-360 cm layers in the growing stage nebkhas;the use of soil water in each layer by T.ramosissima was uniform in the stable stage nebkhas;T.ramosissima mainly absorbed soil water in 180-360 and 360-500 cm layers in the decline stage nebkhas,with ratios of 29.0％ and 44.1％,respectively.In autumn,the main water source of T.ramosissima on embryonic stage nebkhas was 360-500 cm soil water;soil water in 180-360 cm layer and 360-500 cm layer was the main water source for T.ramosissima in the grow and stable stage nebkhas;in the decline stage nebkhas,T.ramosissima mainly used soil water in 360-500 cm depth,and the ratio was as high as 92.3％,indicating that T.ramosissima showed different water use strategies in different development stages of nebkhas.
NETL
NSTL
万方数据
维普
