塔里木河下游阿拉干断面胡杨树高的分布和密度

Tree height distribution and density of Populus euphratica forest along the Argan section in the lower reaches of Tarim River

通过小尺度生态监测与遥感数据分析获取塔里木河下游胡杨（Populus euphratica Oliv．）林现状信息，将胡杨个体对输水的响应实测数据和QuickBird影像信息进行对比和分析，“面”上宏观调查与“点”上典型研究相结合，集中对塔里木河下游阿拉干断面设立的100hm2长期监洲样方内的4500棵胡杨树进行了详细的调查。研究表明：胡杨密度随着离河岸距离增加而呈现降低的规律。不同树高的胡杨也呈一定规律分布。树高小于3m的幼树主要分布在距河道50m范围内；树高3-9m之间的胡杨在研究区中占绝对优势；树高大于9m的胡杨在距河道200m内分布比较均匀，200m之外分布稀少。

The Tarim River is about 1 320 km long and thus one of the longest continental inland waterways worldwide. In an undis- turbed state, it is accompanied on both sides by floodplain forests of Euphrat poplars （Popuhls euphratica Oliv.）. The rising watcr consumption in the upper and middle reaches and, in the past decades, massive hydrotechnical interventions during the development of uncultivated land use （cotton growing）, led to the widespread destruction of the natural ecosystems, particularly in the lower reaches of the river where on 320 km the floodplain forests are either highly degraded or dead. Since 2000 the Chinese government has made efforts to restore these ecosystems and conducted ecological water transportation. The study was based on data from ecological monitoring at small-scale and QuickBird image information of the floodplain forests along the lower reaches of the Tarim River. Comparison and analysis of the data was made seeking to determine the response of the P. euphratica to the ecological water transportation. This was combined with the method of macro observation at the ＂surface＂ level and classical rescareh at ＂spot＂ level. The study sample included a total of 4 500 individual trees ofP. euphratica in an area of 100 hectares along the Argan section. The study results showed the following： the density of trees decreases when the distance from the river increases. Groups of the P. euphratica trees with differing heights are also distributed differently. Most of the young trees with a height of less than 3.0 meters grew within 50 meters of the river. Trees with a height of 3.0 - 9.0 meters were dominant in the study area and would grow up to a distance of 200 meters from the river. There were few trees in our sample that grew beyond 200 meters from the river.