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利用稳定同位素技术测定降水、土壤水、植物茎干水的同位素组成,结合多元线性混合模型(IsoSource)确定科尔沁沙地东南部樟子松人工林内樟子松的根系吸水范围以及各水源的水分贡献率。通过连续观测强降水事件前后樟子松水分来源的变化,探究降水对樟子松水分利用的影响。结果表明樟子松茎干水与20cm以下土层的土壤水同位素组成最为接近,樟子松的水分吸收主要集中在这一层(最大取样深度80cm)。IsoSource模拟结果与观测结果一致,土壤水分条件较好时,大约60%以上的水分来自于20-80cm土层;当这一深度土壤含水量降低时,樟子松将会更多地依赖更深层的土壤水分。樟子松根系分布的最大深度远小于地下水位,因此很难利用到地下水。2009年7月13日14.4mm的降水前后,樟子松茎干水同位素组成的变化表明,降水结束后36小时樟子松可以感应到降水对表层20cm土壤水分的补充,这一土层的水分贡献率在接下来的24小时内迅速降低。不同水分条件下水分来源的多样性表明樟子松能较好地适应沙地生境。
The isotope compositions of precipitation, soil water and plant stem-and-stem water were determined by using stable isotope technique. The water absorption range of Pinus sylvestris var. Mongolica in the Pinus sylvestris var. Mongolica plantation in southeastern Horqin sandy land and the water content of the water sources were determined by using the multivariate linear mixed model (IsoSource) rate. By continuously observing the changes of water sources of Pinus sylvestris var. Mongolica before and after heavy rainfall event, the effect of precipitation on water use of Pinus sylvestris var. Mongolica was studied. The results showed that the water content of stem water of Pinus sylvestris was the closest to that of soil below 20cm, and the water absorption of Pinus sylvestris mainly concentrated in this layer (the maximum sampling depth was 80cm). The results of the IsoSource simulation are consistent with the observations. When the soil moisture is good, about 60% of the water comes from the 20-80 cm soil layer. When the depth of soil moisture decreases, Pinus sylvestris will rely more on the deeper layers Soil moisture. Pinus sylvestris distribution depth is much smaller than the groundwater level, it is difficult to use groundwater. The change of isotopic composition of stem water of Pinus sylvestris var. Sylvestris before and after the precipitation of 14.4mm on July 13, 2009 indicates that Pinus sylvestris var. Sylvestris can sense the replenishment of 20 cm of soil moisture on the surface after 36 hours of precipitation. The water content of this layer The contribution rate dropped rapidly over the next 24 hours. The diversity of water sources under different water conditions indicates that Pinus sylvestris can adapt well to sandy habitats.