Study on the Dynamic Vegetation Degeneration in the Minqin Desert Area

Abstract

Nitraria tangutorum,Artemisia arenaria and Ephedra przewalskii are the main species of natural vegetation in the Minqin desert area,especially Haloxylon ammodendron is a key sand-fixation species in this area.In this study,a positioned investigation on the dynamic vegetation degeneration in Minqin was carried out during the period of 2002-2006.The results reveal that the desert vegetation is continuously degenerated,and the vegetation coverage is closely related to precipitation.There is a significant positive correlation between the soil moisture content and the shrubbery density,herbaceous and dominant species vegetation as well as the total vegetation coverage in late-May.Rainfall during the period from May and July is a key factor affecting the desert vegetation coverage and the plant density in the study area.Viewing from the aspect of plant communities,the coverage of Ephedra przewalskii with deep roots and of Haloxylon ammodendron with high plants is comparatively stable.Viewing from the aspect of landforms,the vegetation on mobile and semi-fixed sand dunes is comparatively stable,whereas the vegetation on the fixed sand dunes is seriously degenerated.It is easy to form sand-surface crust and prevent rainwater to infiltrate downward if sand barriers are constructed,such construction,however,is disadvantageous for receiving the limited rainfall,so it is not an ideal measure to construct the clay sand-barriers for fixing sand.