10 a来民勤县荒漠草地植物群落变化与降雨量的关系

目的]研究甘肃省民勤县荒漠草地植被与降雨量的关系。方法]采用样线法和针刺法,对民勤县3种立地条件下的荒漠草地10a植被变化进行4次定位监测,用Excel软件分析植被生长和降水量变化的关系。结果]民勤县大气降水年际间和年内变幅都很大,这对植物生长十分不利。民勤县荒漠草地植被生长所需水分主要依靠大气降水和地下水。西沙窝沙质荒漠草地和红果子井砾质荒漠草地植被完全依靠大气降水存活和生长,植物生长与降水的关系十分密切,其中一年生草本植物最为明显。但是对地下水位较高的白土井盐渍化荒漠草地植物来说,植物生长主要靠地下水,降水将积聚在表层的盐分淋溶到了根系层,对植物生长不利。结论]民勤县荒漠草地植被生长情况虽然受降雨的影响较大。总体上该县植物生长呈现衰败的趋势,荒漠化也日趋加重。

Relationship Between Change of Plant Community and Precipitation in Desert Grassland of Minqin County in Recent 10 Years

Objective] To better understand how precipitation influences plant growth in Minqin County, Gansu Province.Methods] Line transect method and grid stabbing method were used to monitor vegetation change under three site conditions in Minqin County. It was monitored four times during ten years. The investigation data were analyzed by Excel software.Results] Interannual and annual meteoric water changed greatly, which was harmful to plant growth. Some plant growth depended mainly on precipitation in sandy desert grassland of Xishawo and gravel desert grassland of Hongguozijing in Minqin County, and hence plant growth hasd a close relationship with precipitation, especially the annual herb. The other plant depended mainly on groundwater in salinization desert grassland of Baituing where groundwater level was higher. It was harmful to plant growth that the salinity accumulated on surface soil was leached into root zone by precipitation.Conclusion] The plant growth depends on precipitation or groundwater and is influenced by precipitation greatly. The desert vegetation declines gradually and also desertification is aggravated increa-singly in Minqin County.