Study On Structural Characteristics Of Forest Communities In The Eastern Margin Of Elm In Hunshandake Sand

The ulmuspumila woodland is the Hunshandake sand land’s typical zonal community types. This article will study from three different perspectives of site conditions of the east margin sand dunes belong to the Hunshandake sand land’s windward slope, leeward slope and lowland. And by using the belt transect, the Quadrat Method to conduct a study of the ulmuspumila woodland of the east edge of this land and by applying serveral statistical methods such as correlation analysis, difference analysis and multiple comparison to analysis the structure and vegetation characteristics of the community in the east fringe of the sand land.The conclusions can be drawn as follows:(1)The vertical structure of east margin sand dunes belong to the Hunshandake sand land are significantly different. In three different type of sites, the vertical growth of each layer is different:The tree layer’s average coverage of lee slope is the maximum, and the windward slope is the minimum; The average height of the tree layer of the inter-dunes’is the highest, and the lee slope’s is the lowest. The average coverage and the average height of shrub layer were opposite to the tree layer. The average coverage of the herb layer was the same as the tree layer. The survey districts’Ulmuspumila diameter-classes are mainly distributes in the range of 5-20cm, and the age classes are in the range of X2 and X3(namely 10-29 years old)which are belonging to decline population.(2)The vegetation’s distributed rule of these three sites called lee slope, windward slope and the inter-dunes which are belong to the Hunshandake sand land east margin sand dunes are apparently different. There is a pronounced correlation between the site types and plant species:Survey districts’tree layer lee slope(6 species)>inter-dunes (2 species)= windward slope (2 species),shrub layer’s lee slope (14 species)> inter-dunes (11species)> windward slope (7species), herb layer’s lee slope (32 species)>inter-dunes (26 species)> windward (18 species). And in different sites,there will be different vegetation community structures:The community structureof the lee slope is Ulmus pumila+Spiraea pubescens+ Leymus chinensis;The community structureof the windward slope is Ulmus pumila+Prunus sibirica+Leymus chinensis;And the community structure of the inter-dunes is the Ulmuspumila+Spiraea trilobata+Leymus chinensis. The index of species diversity of the tree layer’s was the leeward slope is greater than the lowland and windward slope.And there were no significant differences in species diversity of shrub layer and herb layer. The soil nutrient of the three site types is highest in the inter-land,lowest in the windward land.(3)The elm canopy quantitative Characteristics, species diversity and the soil nutrient from non-projection area to projection area are all increasing.