Abstract:

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.

Key words: groundwater depth, Nitraria tangutorum, coverage, height, atmospheric humidity