Plant Communities and Their Interrelations with Environmental Factors in the Lower Reaches of Tarim River
塔里木河下游植物群落分布格局及其环境解释

The distributive pattern and abundance of desert plant communities were examined in the lower reaches of Tarim river, southern Xinjiang. Eighteen species were collected within 18 sites along a sequence of groundwater tables in six transects. Except for Tamarix ramosissima and Populus euphratica, which were almost distributed across all sites, most of investigated species had low occurrence frequency in quadrats. Corresponce Ordination of a reduced dataset of 18 species revealed a separation of taxa into distinct groups corresponding to the different tables of groundwater. Clearly defined groups of species were strongly associated with three types of groundwater zones: shallow groundwater zones, intermediate groundwater zones and deep groundwater zones, ranging from <3 m, 3-5 m to >m respectively. Four distinctive taxa groups are identified corresponding to the three zones of groundwater table and the several major environmental factors. Canonical Correspondence Analysis (CCA) of the 18 species and seven environmental variables revealed that the most important factors associated with the distribution of species were groundwater table, soil moisture and soil pH value in the lower reaches of Tarim River. From a management standpoint, there is no reason to doubt that the most important factor for restoration of damaged ecosystem in this region is reasonable use of water resources in the whole Tarim river valley, especially in the middle and upper reaches of the river. This study confirms that the planners and managers of nature reserve in this area should take these major environmental factors and species characteristics into account in the process of decision-making.