干旱风沙区不同林龄柠条锦鸡儿水分利用特征研究

Study on Water Use Characteristics of Caragana korshinskii with Different Stand Ages in Arid Sandy Area

【目的】探明干旱风沙区老龄、中龄和幼龄柠条在干旱严苛环境条件下的用水策略,对当地生态环境保护与可持续发展提供理论依据。【方法】采用稳定同位素技术,通过测定柠条可利用的水源和枝条木质部水分的同位素特征比率,应用IsoSource模型对比研究不同林龄人工柠条林主要利用水分来源及各水源的贡献率,并结合土壤水分的补给特征,综合分析人工柠条林对干旱严苛环境的适应机制。【结果】在整个生长季,3种林龄柠条在0~40 cm浅土层土壤含水量较为波动,在160~200 cm深土层柠条土壤含水量较为稳定。不同林龄柠条0~200 cm土层平均土壤含水量为建植20年>建植8年>建植4年。不同林龄柠条各土层水分贡献率均不同,建植20年的柠条主要利用土层80~120 cm的土壤水分,贡献率为49.5%;建植8年的柠条主要利用0~20 cm和80~120 cm土层土壤水分,贡献率分别为59.2%和14.8%;建植4年的柠条主要利用土层0~20 cm的土壤水分,贡献率达85.7%。【结论】不同林龄柠条用水策略与各土层土壤含水量的高低有直接关系。土层土壤含水量高低决定各土层水分贡献率的大小。老龄柠条主要利用深层土壤水分,中龄柠条主要利用浅层和中层土壤水分,幼龄柠条主要利用浅层土壤水分。

【Objective】The water use strategies of old,middle-aged and young Caragana korshinskii under drought and harsh environmental conditions in the arid sandy area were explored,which provided the theoretical basis for the ecological environment protection and sustainable development in local area.【Method】The stable isotope technology was used to determine the available water source of C.korshinskii and the isotope characteristic ratio of xylem water of branches.The IsoSource model was adopted to compare the main water use sources and the contribution rate of each water source at different stand ages of artificial C.korshinskii forest.At the same time,combined with the characteristics of soil water recharge,the adaptation mechanism of artificial C.korshinskii forest to drought and harsh environments was comprehensively analyzed.【Result】During the whole growing season,the soil water content of C.korshinskii at 0-40 cm shallow soil layer fluctuated relatively,while the soil water content at 160-200 cm deep soil layer was relatively stable.The average soil water content of 0-200 cm soil layer of C.korshinskii with different stand ages showed a trend of 20 years>8 years>4 years.The water contribution rate of each soil layer at different stand ages was different.C.korshinskii planted for 20 years mainly used soil moisture at 80-120 cm soil layer,with a contribution rate of 49.5%.C.korshinskii planted for 8 years mainly used soil moisture at 0-20 cm and 80-120 cm soil layers,and the contribution rates were 59.2%and 14.8%,respectively.C.korshinskii planted for 4 years mainly used soil moisture of 0-20 cm soil layer,and the contribution rate reached 85.7%.【Conclusion】The water use strategies of C.korshinskii with different stand ages have a direct relationship with the soil water content in each soil layer.The soil water content in soil layer determines the water contribution rate in each soil layer.The old C.korshinskii mainly uses deep soil moisture,the middle-aged C.korshinskii mainly uses shallow and middle soil moisture,and the young C.korshinskii mainly uses shallow soil moisture.