民勤绿洲边缘地下水位变化对植物种群生态位的影响

在民勤绿洲边缘,利用空间区域不同地下水位(湖区8～12m,泉山区15～17m,坝区20～23m)和时间序列(1984～1992年)民勤沙井子地区地下水位下降(7.45～11.65m)梯度,研究地下水位下降对荒漠植物种群生态位的影响。结果表明:空间区域地下水位下降,植物种群生态位宽度均减小,种群退化;时间序列地下水位下降,白刺种群在扩展,其它植物种群在退化。白刺种群生态位宽度在民勤绿洲边缘荒漠植物群落中最大,是该区的建群种。由于白刺种群在地下水位7.45～11.65m范围内扩展,民勤绿洲生态环境治理中地下水位达到该范围是一个主要目标。

Effect of water table to niche of plant population at Minqin oasis fringe

At Minqin oasis fringe,effects of descending water table to niche of plant population was studied using spatial difference of water table(8-12 m in Huqu region,15-17 m in Quanshan and 20-23m in Baqu) and the descending grades of water table during 1984 to 1992(7.45-11.65 meter) in Sha-jin-zi.The result reveals:with the descending of underground water in different regions,the breadth of niche of plant population decreases,and the population degenerates;with the descending of water table in time grade,Nitraria tangutorum population extends,while the others decrease.Nitraria tangutorum,with the widest breadth of niche among the desert plant communities at Minqin oasis fringe,is the dominant species in this region.Nitraria tangutorum population generally extends at a water table ranging from 7.45 m to 11.65 m,so the critical water table for improving eco-environment of Minqin oasis should be within this scope.