【摘要】 利用稳定同位素技术,测定共和盆地不同林龄(5、9、25 a)乌柳枝条木质部和土壤各层水分的δD值、δ18O值,分析它们是否随林龄变化而选择性地利用不同深度的土壤水分,并通过测定不同林龄乌柳叶片的δ13C值,分析比较它们的长期水分利用效率。结果表明:5 a乌柳主要利用源自降雨的10～50 cm深处的浅层土壤水分,9 a乌柳主要利用降雨补充的20 cm和地下水补充的30～50、150 cm深处的土壤水分,25 a乌柳主要利用降雨补充的10～20cm和地下水补充的50 cm深处的土壤水分。3个林龄乌柳的水分利用效率差异显著,5 a乌柳的水分利用效率明显高于9 a和25 a乌柳,9 a和25 a乌柳水分利用效率类似。水分利用策略的分析结果表明:9～25 a乌柳处于稳定时期。更多还原

【Abstract】 Salix cheilophila is one of the main shrub species for afforestation in Alpine Sandland of Gonghe Basin,Qinghai Province.Stable isotope technique was used to test the δD and δ18O value of rain,well water,branch xylem and different soil depth of 5-,9-and 25-year-old S.cheilophila plantation,and then the differences of main water source among the three S.cheilophila stands with different ages were analyzed.Also,the δ13C value of leaves was tested to evaluate the water use efficiency(WUE) of the S.cheilophila stands.Comparison of δD and δ18O showed that 5-year-old S.cheilophila used the water in 10-50 cm soil infiltrated from rainwater;9-year-old S.cheilophila consumed relatively deep soil water,including 20 cm infiltrated from rainwater and 30-50,150 cm replenished by ground water;and 25-year-old S.cheilophila used 10-20 cm soil water infiltrated from rainwater and 50 cm soil water replenished by ground water.The difference of leaf δ13C value among 5-,9-and 25-year-old S.cheilophila stands was significant;5-year-old S.cheilophila has exclusively high WUE,whereas that of 9-year-old and 25-year-old stands were similar.The water source and WUE suggest that 9-25 years old S.cheilophila was in steady period.更多还原