Ziwuling Forest Species Diversity Of Multi-scale Study

The ecosystem on Loess Plateau was on the status of being extremely degraded, taking effective protection and management for forest vegetation diversity is the important symbol and content on the protection and reconstruction of degraded ecosystem. At present, there are many researches correlated to the species diversity of forest communities on Loess Plateau, but analyses based on multiple scales are less. The patterns of species diversity are closely related to selected scales, and change with different spatial, temporal and organizational scales. Analyzing species diversity based on multiple scales helps comprehensively and objectively understands the species diversity in the region, and successful forest protection plan should take consideration of the effects taken on different scales. Therefore, analyzing species diversity at multiple scales was the start point in our research. The spatial scale was introduced, and the research of species diversity based on multiple organizational scales was first brought about in this paper. In consideration of different vegetation characteristic and terrain situation in different researching areas, two different ways was used to analyze the vegetation characteristic. Through comparisons among different sales in one research, comparisons of results among different regions, and comparisons between spatial scale and organizational scale, the regular pattern and characteristic of species diversity were comprehensively and systematically analyzed.The key to analyze the relationship between scales and species diversity is to select the proper method, quantitatively analyzing how regional species diversity distribute at different scales is the basic way. The additive partition approach (γ=α+β) allow the comparative researches on a andβdiversity across scales, which can help better analyze the laws of species diversity changing with scales. There are many researches on species diversity across scales by using additive partition approach abroad, but relevant researches at home are less. Besides, there is no report on species diversity analysis based on vegetation organizational scales at home and abroad. Except for spatial scale, additive partition approach can be used at organizational scale, temporal scale and so on. any classifying factors, such as resource utilization pattern,habitat and so on. can be analyzed by the approach. Therefore, the additive partition approach was firstly introduced into the multiple scale research on Loess Plateau, and the additive partition approach was creatively introduced into the multiple analyses of vegetation organizational scales, which is the first case in the home and abroad.The laws of species diversity of Pinns tabulaeformis f.shekannesis community changes with spatial scales, as well as the laws of species diversity of Malan forest community changes with vegetation organizational scales on Loess Plateau were analyzed. The variation laws of species diversity in the research place based the spatial and organizational scales were elaborated, the importance of these findings to reveal species diversity pattern and process was analyzed. Furthermore, the significance of using additive partition approach into muti-scale researches was discussed. The results provided theory proofs for the protection and management of forest species diversity in the region. The results are as follows:1. By using additive partition approach, the distribution relationship of tree, shrub and herb layer's species diversity among three scales:quadrat, slope position and slope in Pinus tabulaeformis f. shekannesis community was analyzed. The results show that:(1) Slope scale is the key scale for species composition and maintenance:Slope scale contributed most to regional diversity when measured as species richness, which indicating that it was the critical scale for species composition and maintaining in the region. When Shannon and Simpson diversity were used as indices, the highest contribution to diversity was distributed in quadrat, it was because that the two indices not only considered the number of species, but also considered species abundance in quadrat, as well as the influence and role of common and rare species. (2) Rare species play a decisive role on species diversity pattern:The proportions ofβdiversity's contribution to regional diversity measured as Shannon diversity were higher than that measured as Simpson diversity in between-quadrat. between-slope position and between-slope scales, which was mainly decided by the distribution pattern of rare species among the scales. (3) There were differences among the orders ofβdiversity in scales of between-quadrat. between-slope position and between-slope, which was closely correlated with tree, shrub and herb layer's species composition and distribution in the community, as well as environmental heterogeneity among different scales.2. By using additive partition approach, the distribution relationship of tree, shrub and herb layer's species diversity among three scales:vegetation scale, formation scale and association group scale in Malan forest region was analyzed. The results show that:(1) Association group scale is the key scale for species composition and maintenance:For the four components constituting regional diversity(α1,β1,β2andβ3),no matter if diversity was measured as species richness. Shannon-Wiener or Simpson indices-within-association group diversity always contributed the most to regional diversity in tree, shrub and herb layers (except species richness in the herb layer), indicating that it was the most appropriate scale for measuring species diversity. (2) Rare species play a decisive role on species diversity pattern:The proportion of Shannon-Wiener diversity at the vegetation type, formation or association group scales was higher than the proportion measured by Simpson diversity. which resulted from the distribution pattern of rare species on each scale. (3) Differences among the orders ofβdiversity components were observed in scales of between-vegetation type. between-formation and between-association group, which were mainly correlated with tree. shrub and herb layers' species composition and distribution in the region, as well as environmental heterogeneity among different scales.