甘肃民勤荒漠区植被演替特征及驱动力研究——以民勤为例

Study on Features of Vegetation Succession and its Driving Force in Gansu Desert Areas—A Case Study at Minqin County

通过对40多年来民勤荒漠植被类型、植被演替特征的分析,发现民勤荒漠区的自然植被类型20世纪50年代大体可分为5个植被型,19个群系,现在只有9个群系;民勤土地旱化现象日趋严重,脆弱的生态系统进行着逆向演替,群落的生物多样性及植被类型减少,生态系统的稳定性减弱且结构趋于简单、功能衰退,荒漠植被进一步取代了草甸植被成为优势种,生态位变宽;同时,通过对地下水位、降水量、植被盖度近20a的定位观测,定量研究植被退化的驱动因子表明:人类的各种经济活动导致地表径流的大幅度减少、超采地下水,使地下水位急剧下降,成为植被退化最直接的根源。

Through analyzing on the over 40 years' data of vegetation types and changes, the natural vegetation in 1950s at Minqin could be divided into 19 formations, 5 vegetation types, and among the 19 formations only 9 formations left nowadays. The water content of the soil is reduced seriously so that the stability of ecosystem losses equilibrium, the succession of vegetation reverses, and the composition, structure and function of ecosystem decreases both on time and space. Desert plants are trend to replace salt plants. The fix-site observation for 20 years to underground water level, precipitation, and vegetation coverage indicated that the main driving force for vegetation degradation is the considerably surface runoff reducing resulted from irrational human being's economic activities, and the underground water table sharply lowering duo to over-pumping.