The Influence of the Dam Construction on Plant Types in Shiyang River

Abstract

Shiyang River Basin, as the high extent of exploitation & utilization of its resources and severe ecological & environmental issues, has always received much attention from scholars at home and abroad. The research, with reference to previous scholars’ conclusion and field survey, showed that the dam construction has resulted in the radical changes of water resource distribution as well as water resource utilization mode, which eventually had a strong effect on plant species and community change along the middle and lower reaches of the Shiyang River. The mainly result include: 1) The vegetation area, vegetation cover and biomass all decreased, plant types had changed from wet series to xeric series, Tamarix ramosissima, Kalidium foliatum and Phragmites australis etc community had gradually decreased, the vegetation with more drought tolerance had gradually occupy the dominant position, mainly includes Nitraria tangutorum, Reaumuria soongarica, Lycium ruthenicum etc, especially Nitraria tangutorum had become constructive species in most of the place in the middle and lower reaches of the Shiyang River since 1950's. 2) In the middle and lower reaches of the Shiyang River, The vegetation formed various adaptive way and xeromorphic characteristics in order to adapt the adverse environment such as the serious sand storm, the higher difference of temperature between day and night, the lower precipitation and the higher evaporation etc. The ring gate types gradually became the main types of structure of leaf in the region of relatively severe of human disturbance, the full gate types plants and normal types plants gradually increased in the region of relatively less of human disturbance, the type of structure of leaf changed from the ring gate types and normal types to irregular molding in the region of sharply decreased of groundwater. The dam construction caused reclaiming wasteland for farming on a large scale, disproportionate use of water resource, groundwater overdraft of and deterioration of water quality etc, and this eventually lead to change of areas and types of vegetation.