近40年玛曲草地暖干化趋势及影响因子分析

The trend and impact factors of dry and wet changes in Maqu county in recent 40 years

通过利用Holdridge可能蒸散率(PER),对玛曲草地1971～2010年的干湿变化特征进行了分析,近40年玛曲草地PER呈明显的上升趋势,上升趋势达0.03/10a,20世纪90年代后,玛曲草地PER持续偏高,并在1993年出现了增大突变,降水量以7.4mm/10a的趋势减少,温度以0.46℃/10a的趋势上升,生物温度以0.25℃/10a的趋势上升,降水量与生物温度呈现出明显反向变化,玛曲草地有从极湿润区向湿润区过渡的趋势,出现了明显的暖干化趋势。主成分分析表明玛曲草地暖干化的主要原因是气温升高,同时日照时数增加、降水量减少、相对湿度下降和风速减小加剧了暖干化的趋势。受气候暖干化和人为因素的影响,玛曲草地出现了明显的退化和沙化,沼泽湿地的面积也呈明显的减少趋势,导致玛曲草地牧草产量下降,涵养水源能力急剧下降和生物多样性锐减。

Through the PER（potential evapotranspiration rate） defined by Holdridge,we analyzed the features of dry and wet changes for nearly 40 years in Maqu grassland.The results indicate that the PER-level showed an obviously increasing trend and the speed rose up to 0.03/10a from 1971 to 2010.Especially after the 1990s,the PER-level increased duratively and appeared dramatically increasing in 1993.Besides,the precipitation and organism temperature presented reverse change visibly.The climate of Maqu grassland had a transition from extremely humid to semi-humid.Under the influence of climate worming-drying and human factors,the grassland appeared obvious degradation and desertification in MaQu.Obviously,the acreage of swamp and wetland was decreasing,leading to a decline in grassland yield in MaQu.The ability of water conservation shew a sharp decline and biodiversity species reduced abruptly.The conclusion is that the worsening trend of warming and drying of Maqu grassland is caused by the temperature rising,also the sunshine duration increasing and precipitation decreasing intensify this trend.