Effects Of Living Sand-barrier On Dune Vegetation In Horqin Sand Land

The 4m×4m gridding Salix gordejevii and Hedysarum leave Living Sand barriers that established in autumn from 1998 to 2002 were chosen to set 5 sample plots on windward slope in mobile dune in Horqin sands. in order to The vegetation, root systemand and soil seed bank were investigated with spatial sequence instead of time series.The results were shown as follows:1. The aboveground biomass and coverage of Salix gordejevii and Hedysarum leave are increasing year by year in three-year and five-year sample plots, but they decrease in the six-year. In the seven-year sample plot, there is a good growth status after stumping treatment. The deadwood biomass of Salix gordejevii and Hedysarum leave has a increasing trend with the time.2. Under the protection of Living Sand-barrier, species richness in the phytocommunity, aboveground biomass and coverage are increasing year by year. The component of species, family and genera tend to be diversification. Species Diversity index in three-year sample plot is minimum, while the ecological dominance is maximum. And evenness index decrease year by year from three-year to seven-year sample plots. Similar Coefficients of Community is relative small when there is great time difference between sample plots. The litterfall in grids and it's coverage are increasing with the time.3. At 0-50cm soil layer, the whole root biomass between grids in different sample plots and bellowing Hedysarum leave is increasing with the time. In the same sample plot, the whole root biomass bellowing Hedysarum leave is more than that of interspace.4. In the sample plots of three-year, five-year and seven-year, the vegetation types and seed density in soil seed bank are increasing year by year. The changed tendency of species diversity index and similar coefficient is not obvious.