Study On Temporal And Spatial Variation Of Soil Seed Bank About Semi Fixed Sand Under Different Micro-landform In Desert Steppe

Soil seed bank is an important part of the ecological system in desert steppe. It plays a very important role in the community succession、update and ecological restoration. In the same climate zone, the change process of land-form formed by different topography has a direct impact on ground vegetation and soil seed bank. Changing of vegetation pattern have a vital link with the undulating terrain. Study on the vegetation characteristics、temporal and spatial variation pattern of soil seed bank、 the relationship of soil seed bank and above-ground vegetation on semi fixed sand of different micro topography in Yanchi. In order to provide a theoretical basis for the ecological restoration on vegetation in Desert Steppe.This study used the field investigation and indoor cultivation combined research methods of ecology, and selected two semi fixed sand dune with the similar terrain features then divided into 5 types of micro land-form(Crest slope,Upper side slope, Middle side slope,Lower side slope,Bottom slope). Field sampling and indoor germination were conducted in June, September, December of 2013 and in March of 2014. At the same time, invested the ground vegetation at the end of June、July and at the early of August of 2013 to study the vegetation characteristics、temporal and spatial variation pattern of soil seed bank、the relationship of soil seed bank and above-ground vegetation on semi fixed sand of different micro topography in Yanchi.The result showed that:1.There were 35 species in soil seed bank and above-ground vegetation in semi fixed sand of different micro topographic in Yanchi, there were 31 kinds of species in soil seed bank and 19 kinds of species in ground vegetation. There were found 15 species both in soil seed bank and ground vegetation, 4 species appeared only in ground vegetation and 16 species appeared only in soil seed bank;2.From CS to BS the number of species on ground vegetation、individual coverage and frequency of species、all the above-ground biomass and total biomass and soil seed bank reserves are all showed an increasing trend.Meanwhile, with the increased of depth about the soil, soil seed bank reserves has shown a decreasing trend,the lower slope of ecological environment factors is more suitable for the ground vegetation growth and seed survival;3.The ground vegetation of Different micro land-form in semi fixed sand, annual herbs were the largest proportion(47.37%～66.67%), followed by perennial herbs(22.22%～42.11%), shrubs was minimum(7.69%～11.11%). Meanwhile, in soil seed bank of four different seasons, annual herbs were the largest proportion(60.00%～64.71%), followed by perennial herbs(23.53%～33.33%), shrubs was minimum(6.67%～11.76%).4.The total number of species of soil seed bank was maximum in March, followed by December, September was minimum. With the increase of sampling depth, the soil seed bank species richness was decreased, but from CS to BS showed a rising trend in June and September,it was in the state of fluctuation in March and December; The soil seed bank Simpson and Shannon-Wiener diversity index were decreased with the increase of sampling depth, but from CS to BS showed a rising trend in March, they were in the state of fluctuation in June、September and December; With the increase of sampling depth, the soil seed bank uniformity coefficient was increased, and from CS to BS showed a rising trend too in March,it was in the state of fluctuation in June、September and December.