民勤西沙窝沙区不同演替阶段植被变化特征研究

hrough eco-measurement and research at the Xishawo desert pasture in Minqin for 60 a, it was foundthat desert vegetation flora has experienced four main stages with ground water- table decline, they were thedegraded meadow steppe and Tamarix flora, Tamarix and Nitraria flora, Nitraria and degraded Tamarix flora, andNitraria flora, the plant diversity and coverage dcreased in the processing, eco- degradation and desertificationdeveloped remarkably; with rain-fed area enlargement, desert herbal plants grew when precipitation was higher inthe year, the plant diversity and coverage increased, and vice versa; some desert shrubs were relatively stable, itspopulation growth and development improved when precipitation was over 140 mm, 100-140 mm for basicgrowth, and < 100 mm degraded gradually; most plant species of windbreak and sand- fixation afforestationdegraded under drought conditions, Haloxylon ammodendron had strong eco- adaptability as an introducedspecies, it has developed into the biggest man-made windbreak and sand-fixation forest in Minqin desert areas, itsbig density and drought land were the main reasons for degradation, and sustainability could be increased underlow density afforestation according to local plant carry capacity. Recently, with the integrated programimplementation in the Shiyang River watershed area, eco- water has been increased, groundwater table hasincreased in some surroundings, some micro-wetlands have formed, original desert meadow steppe has reoccured,and their ecosystems are developing positively; however, ground water table still reduces slowly in most desertareas, and desertification has developed.