黑河下游不同林龄胡杨水分来源的D、^(18)O同位素示踪

Application of D and ^(18)O stable isotopes in analyzing the water sources of different ages of Populus euphratica in the lower reaches of the Hei River

对黑河下游不同林龄胡杨木质部水及其不同潜在水源稳定同位素组成(δD、δ18O)的测定分析,探讨不同潜在水源对胡杨的贡献。结果表明:(1)不同林龄胡杨木质部δ18O差异显著,胡杨幼苗、成熟木、过熟木的δ18O值分别为-5.368 14‰、-6.032 75‰和-6.924 18‰;(2)不同林龄胡杨所利用的水分来源不同,胡杨幼苗主要利用30~50 cm的土壤水,利用率在70%左右,对地下水的利用仅为6%;成熟木主要利用200~220 cm的土壤水及地下水,对地下水的利用最多达85%;胡杨过熟木主要利用100~260 cm的土壤水及地下水,深度范围较幼苗和成熟木都广,对地下水的利用较高,最多达96%,胡杨成熟木和过熟木主要利用的是地下水。

Research on the water sources of different ages of Populus euphratica plays a key role in formulating the conservation strategy of Populus euphratica. This study discusses the contributions of different potential water sou- rces to Populus euphratica, based on the composition of the stable oxygen and hydrogen isotope （ δ ^18O, 8 D） of the xylem in different ages of Populus euphratica and different potential water sources in the lower reaches of the Hei River. The results showed as follows ： （ 1 ） there were significant differences of δ ^18O value in the xylem of different ages of Populuseuphratica. The 8 180 values of the seedlings, mature wood and over-mature wood of Populus euphratica reached -5.368‰, -6.033‰ and -6.924‰, respectively. （2）The water utilization of different ages of Populus euphratica came from different sources. The seedlings of Populus euphratica mainly used the soil water in 30-50 cm layers, with the utilization rate of 70%, while the utilization rate of groundwater only about 6%. The mature wood of Populus euphratica mainly used the soil water in 200-320 cm layers and the groundwater, with the largest utilization rate at 85% of the groundwater. The over-mature wood of Populus euphratica mainly used the soil water in 100-260 cm layers and also the groundwater,with the higher utilization rate （about 96%） of the ground- water. And the depth range of the over-mature wood is wider than that of seedlings and mature wood of Populus euphratica.