Spatial Variability Of Woody Plants Species Diversity Of Broad-leaved Korean Pine Forest In Xiaoxing?an Mountains

Species diversity and spatial distribution are the main content and important part of biodiversity research,which are of great significance to study the community structure and protect species diversity.The species-area relationship(SAR)is an important basis for biological diversity scaling,and also an important way to understand the structure of community.Therefore,SAR is a core component of community ecology.Here,based on the inventory data from two 10.4hm~2 plots and five 1.0hm~2 plots in the broad-leaved Korean pine mixed forests in Xiao Xing?an mountains,Heilongjiang Province,mainly researches were carried out in the following three aspects:(1)The minimum sampling areas were determined by species-area curves with the moving window method,which overcame the limitations of the nested sampling and quadrate combination methods,and prevented the interference of sampling error on the SAR caused by the community spatial heterogeneity.We choose a logarithmic model,a power function model,and a logistic model to fit the SAR of a broad-leaved Korean pine forest.After that,we compared the suitability of these fits in different research areas.(2)The quantitative characteristics of species diversity and importance value at different scales were calculated with the moving window method,which traversing the entire plot by a moving window,and making the spatial distribution heterogeneity of species diversity and importance value were fully considered.Based on these,we determined the minimum area of the community,and analyzed the species composition and the spatial distribution of species diversity.(3)By simulating the process of random sampling,we determined the number of samples required for species diversity and importance value with minimum area,and then compared the community structure of different plots in Xiao Xing?an mountains.The main results are as follows:The establishment of a SAR was closely related to the sampling scales.The logarithm model was superior to the power function model at the small and moderate scales for broad-leaved Korean pine forest,while the logistic model better fitted the SAR than did the logarithm and power function models at the large scale.However,the logistic model was still the preferred model for fitting the SAR in Xiao Xing?an mountains,and logarithm model should be given priority in logarithm model and power function model.In seven plots,the species composition of woody plants was different,but Pinus koraiensis was the dominant species in all plots.The species diversity of plot at Tangwanghe was the lowest and plot at Fangzheng was higher than other plots.Species diversity and its spatial distribution have scale effect,Simpson index and importance value of dominant species rapid changed with the scale,after reach a certain scale they remained stable.Importance value of different species show different trends as the scale increasing.Pinus koraiensis with the sampling scale increased performance for the growth trend and other woody plants showed a downward trend.Species diversity of plot at Fangzheng is smaller than others at the small and moderate scales,while species diversity of plot at Fangzheng higher than others at large scale.The minimum area is the area which can fully demonstrate the species composition and structure characteristics of the community.In seven plots,the minimum area determined by the diversity index and the importance value is slightly smaller than those determinedby the SAR.The minimum areas determined by the SAR and importance value of dominant species were the same among the seven plots,which can not reflect the differences in community structure.Only the minimum area determined by the diversity index can reveal the difference in community structure between seven plots.The differences in community structures could be reflected in the demands of sampling numbers.Plots at Fenglin and Daliangzihe required only a small number of samples,indicating an even spatial distribution of species diversity.However,the plots at Fangzheng and Shengshan required a large number of samples,indicating high spatial heterogeneity in the species diversity distribution.Further studies are required to determine the mechanisms responsible for this difference.