以乌兰布和沙漠东北缘唐古特白刺为研究对象,选择沙漠与绿洲过渡的大气干燥区以及绿洲与其东南缘黄河之间、靠近黄河西北岸的大气湿润区作为对比研究区段,分析地下水位在2种不同大气干燥程度下对白刺盖度、高度生长的影响。结果表明: 不同的地下水位和大气干燥程度对白刺的盖度及高度生长都有显著影响。在绿洲外围干燥区段,白刺盖度、高度分别与地下水位表现出指数增长趋势; 根据曲线拟合预测: 盖度、高度生长的最佳地下水位区间均为2 500~9 000 mm。在湿润区段,白刺盖度、高度随地下水位分别表现出高斯变化曲线; 高度生长比盖度表现出更宽的地下水位阈值; 根据曲线拟合预测: 高度生长的最佳地下水位区间为1 000~9 000 mm,盖度的最佳区间为2 000~7 500 mm。
Groundwater is one of the most important factors in desert ecosystem. The objective of this paper was to study impact of groundwater depth on height growth and the coverage of Nitraria tangutorum under the conditions with different atmospheric humidity. The transit dry area from the desert to oasis and the humid area along the yellow river bank between the oasis and the yellow river on the northeast of Ulanbuh desert were selected as site area. After collecting the data by using the contiguous quadrats, the groundwater depth was divided different layers based on 100 mm. The results showed that both the groundwater depth and the atmospheric humidity had effects on the height growth and coverage of N. tangutorum. In the dry area, the coverage and height of N. tangutorum showed an exponential growth with the increase of groundwater depth. Both the best groundwater depth range for N. tangutorum growing in cover and height were 2 500-9 000 mm according to the curve fitting. In the humid area, both the cover and height of N. tangutorum showed a Gaussian graph with the increase of groundwater depth. Moreover, the height growth adapted wider groundwater depth range than the cover. The best groundwater depth range was 1 000-9 000 mm for height growth and 2 000-7 500 mm for cover according to the curve fitting.