塔里木河下游典型荒漠河岸植物水分来源

通过对塔里木河下游典型荒漠植物河岸胡杨（Populus euphratica，成年和幼龄）、柽柳（Tamarix ramosissima）、甘草（Glycyrrhiza inflata）、骆驼刺（Alhagi sparfolia）木质部水及不同潜在水源的稳定性氧同位素值的测定，并利用多源线性混合模型（IsoSource）和相似性比例指数（PS指数）分别分析了各潜在水源对不同植物的贡献率以及各月份不同植物间的水分利用关系。结果表明：（1）在塔里木河下游，成年胡杨、幼龄胡杨、柽柳几乎都不利用0~50 cm的表层土壤水，而主要利用200 cm以下的深层土壤水和地下水，而甘草、骆驼刺主要吸收50~200 cm的土壤水。（2）在生长季的不同月份里，除个别月份外，胡杨（成年和幼龄）、柽柳之间存在激烈水分竞争；甘草、骆驼刺在生长旺季和末期对各水源都存在较强的竞争关系，而成年或幼龄胡杨、柽柳和甘草、骆驼刺之间水分竞争关系较弱。（3）在塔里木河下游，为了适应极端干旱，无论是乔木胡杨、还是灌木柽柳，水分来源主要是较稳定的深层水源，且对各水源的利用比例在不同月份波动不大。

Water Sources of Typical Desert Riparian Plants in the Lower Reaches of Tarim River

The Lower Reaches of the Tarim River is featured with an extraordinary dry and hot climate.Vegetation here has a harsh environment to survival, and water is the most crucial ecological factor. The research of water sources used by desert plants in the growing season helps to understand the water use strategy of the desert plants, which will be useful to vegetation reconstruction in the Lower Reaches of Tarim River. In this study, the stable oxygen isotope (δ¹⁸O) of stem water of four dominant plant species, groundwater and soil water in the lower reaches of Tarim River were measured in May, July, August and September, 2015. And then we used the Multi-source mixed liner model (IsoSource) to analyze the probable contribution of potential water sources used by these dominant desert plants. In addition, we use the proportional similarity index (PSI) to analyze the water use relationship between different desert plants. The result indicated that: (1) in the Lower Reaches of Tarim River, Populus euphratica oliv (young and mature) and Tamarix ramosissima can hardly use soil water stored at 0-50 cm depth, but mainly uptook deep soil water stored below 200 cm depth and groundwater, Glycyrrhiza inflata and Alhagi spar folia mainly acquired soil water stored at 50-200 cm depth. (2) During growing season, P. euphratica oliv (young and mature) and T. ramosissima had a fierce water competition, except for individual months. lycyrrhiza inflata and Alhagi spar folia also had a strong water competition, however, P. euphratica oliv (young and mature) and T. ramosissima had a weak water competition with G. inflata and A. spar folia. (3) In order to adapt extremely drought environment, P. euphratica oliv (young and mature) and T. ramosissima had a stable water sources, and the feasible proportion of water sources used by different plants had a slight fluctuation in the Lower Reaches of Tarim River.