高寒沙地不同林龄中间锦鸡儿的水分利用策略

中间锦鸡儿是青海共和盆地高寒沙地的主要造林灌木树种之一。文中利用稳定同位素技术,测定共和盆地不同林龄(5a,9a,25a)中间锦鸡儿枝条木质部和土壤各层(10,20,30,50,100,150,200cm)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中间锦鸡儿叶片的δ13C值,分析比较它们的长期水分利用效率。结果表明:5a,9a和25a中间锦鸡儿均主要利用源自降雨的土壤浅层10-50cm的水分。3个林龄中间锦鸡儿的水分利用效率差异显著(P<0.05),5a中间锦鸡儿明显高于9a和25a中间锦鸡儿,9a和25a中间锦鸡儿水分利用效率类似。水分利用策略的分析结果表明,中间锦鸡儿在发育低龄期,采取提高水分利用效率的方法来应对干旱胁迫。25a中间锦鸡儿未发生明显退化。

Water use strategy of different stand ages of Caragana intermedia in Alpine sandland

Caragana intermedia is one of main shrubs for afforestation in Alpine sandland of Gonghe Basin,Qinghai Province.Stable isotope technique was used to test the δD and δ18O value of water in rain,well,branch xylem and different soil depth(10,20,30,50,100,150,200 cm) of 5 years,9 years and 25 years C.intermedia plantation,and then the differences of main water source among three ages of C.intermedia were analyzed.Also,the δ13C value of leaves was tested to evaluate the water use efficiency(WUE) of three ages of C.intermedia.Comparison of δD and δ18O showed that 5 years,9 years and 25 years of C.intermedia stands used the water in 10-50 cm soil which came from rainwater.The differences of leaf δ13C values among 5 years,9 years and 25 years C.intermedia were significant;5 years C.intermedia had exclusively high WUE,whereas that of 9 years and 25 years C.intermedia were similar.The water source and WUE suggest that 5 years C.intermedia adapted to drought stress by increasing WUE.And 25 years C.intermedia was not degenerated obviously.