民勤绿洲边缘地下水埋深对柽柳灌丛生长及物种多样性的影响

采用空间替代时间方法,以柽柳灌丛为研究对象,研究了民勤绿洲边缘地下水深对柽柳灌丛的生长、演变及物种多样性的影响。结果表明:随着地下水位的不断下降,柽柳灌丛逐渐衰退,以白刺、红沙为主的荒漠植物逐步发展为优势种群。柽柳生长的最适生态水位2~3 m,生态警戒水位4 m,死亡临界地下水位10 m。当地下水位10 m,降水和地下水共同作用导致组成柽柳灌丛的物种数最多。当地下水位下降到10 m以下,生长在固定沙丘上的柽柳衰退速度快于半固定沙丘。

Impact of groundwater level on growth and species diversity of Tamarix ramosissima community around oasis fringe in Minqin

The relationship between groundwater level changes and Tamarix ramosissima community was studied in order to offer the scientific evidences for the recover of degraded T.ramosissima community in the oasis fringe in Minqin.The results showed that T.ramosissima community succeeded gradually to Nitraria tangutorum and Reaumuria soongorica communities along with the decrease of groundwater level.The depths of 2 to 3 m,4 m and 10 m of groundwater level were the optimum,warning and death critical levels individually.The species number was the highest while the groundwater depth was around 10 m.The degraded speed of the T.ramosissima community on fixed sand dune was faster than that on semi-fixed sand dune when the groundwater level dropped less than 10 m.