Response of Desert Riparian Forest Vegetation to Groundwater Depth Changes in the Middle and Lower Tarim River
塔里木河中下游荒漠河岸林植被对地下水埋深变化的响应

Based on the data collected from 74 vegetation plots and groundwater depth monitoring wells (2006 to 2007) in the middle and lower reaches of the Tarim River, the groundwater table was divided into six gradients (0-2, 2-4, 4-6, 6-8, 8-10 and >10 m) to compare the influence of groundwater level on coverage, plant diversity and plants appearance frequency. The results showed that plant diversity was the highest at the 2-4 m level, followed by 4-6 m and then 0-2 m. When the groundwater depth dropped to below 6 m species diversity decreased tremendously, and the slope of the Hill's index (diversity ordering) tended to level off. Thus, the optimum groundwater level for major plants growth is 2-4 m and the threshold groundwater depth is about 6 m. To restore vegetation and ecosystem of the lower reaches of the Tarim River, the groundwater depth must be kept at a minimum of 6 m.