Study On The Community Characteristics And Biomass Of Natural Juniperus Rigida In Huanghua Mountain Of Xianghuang Banner

The natural juniper us rigida forest in Huanghua Mountain of Xianghuang Banner is a precious juniperus rigida forest which was formed under special ecological conditions. Due to overgrazing and deforestation in the late1970s to early1980s, natural juniperus rigida forest vegetation has been severely damaged. It can provide a theoretical basis for stable recovery of the community and the artificial management and protection by conducting study of community characteristics and biomass of the natural juniperus rigida. The object of study was natural juniperus rigida community in Huanghua Mountain, and the main content was about community structure, species diversity, distribution patterns and biomass research of natural juniperus rigida by the method of combining field investigations and laboratory experiments. Draw the following main conclusions:(1) The composition of natural juniperus rigida forest in Huanghua Mountain was25families,53genera and64species. There were6families which included4species or more than4species took up24%of the total number. There were19families which included1～3species took up76%of the total family number. Genus which included1species took a large proportion of total genera. The tree layer contained2families,2genera,3species; the shrub layer contained5families,8genera,11species; the herb layer contained20families,43genera,50species. It was mainly temperate zone and north-temperate zone ingredient on the distribution of geographic composition aspect.(2) The species richness of community was lower. The maximum values of species Margalef richness index and Shannon-Wiener diversity index in tree layer was0.4200and0.8252respectively; the maximum values of species Margalef richness index and Shannon-Wiener diversity index in shrub layer was1.3176and1.7618respectively; the maximum values of species Margalef richness index and Shannon-Wiener diversity index in herb layer was4.4037and2.9712respectively. The species richness of community in different hierarchy was in the order of the herb layer> shrub layer> tree layer.(3) The diameter class structure of distribution of community was uneven, and because there were obvious defects in diameter class, the community was unstable. The juniperus rigida diameter class distribution was in a wide range and the individual peak distribution was more concentrated in the range of4～12cm which accounting for64.57% of the total number of trees; The ground diameter of ulmus glaucescens which was all low shrubs form was below2.5cm. Height class of tree communities was in lower level with an average height of1.69m, so height class structure diagram was the "single peak" type and height of2m above ofuniperus rigida individuals were few.(4) The distribution patterns of juniperus rigida populations was mainly aggregated distribution with uniform distribution pattern, while ulmus glaucescens population was aggregated distribution pattern. The dominant rhamnus paryifolia population and dominant spiraea pubescens population were aggregated distribution pattern in shrub layer. The community was in an unstable stage of recovery development.(5) Using the method of standard wood to study the biomass of tree layer as well as organ distribution of natural juniperus rigida community. The organ biomass accounted for the proportion of the total biomass of the tree layer followed by the trunk> branch> leaf. The maximum biomass of the tree layer, shrub layer and herb layer was2.549t·hm-2,0.398t·hm-2, and1.910t·hm-2respectively on all plots. The total biomass was3.903t·hm-2as the maximum. The ratio that the biomass of different levels accounted for total biomass was in the order of the herb layer> tree layer> shrub layer and the reasons for this phenomenon was less and sparse juniperus rigida individuals. In addition, the canopy density of natural juniperus rigida was lower, so shrubs and herbaceous vegetation were growing well that leading the biomass of tree layer took a smaller proportion.