| The fragmentation of habitats leads to a reduction in the living area of living things,hinders the communication between individual populations,and has a series of effects on the survival and development of living things in living places.Davidia involucrata,as an excellent ornamental tree species and timber tree species,has high ornamental value,medicinal value and scientific research value.Due to the impact of global climate change and human disturbances,the habitat of Davidia involucrata has been threatened to some extent.How to take more scientific and reasonable measures for the propagation and protection of Davidia involucrata population is currently a science that needs to be resolved to study and maintain the stability of Davidia involucrata community.problem.In order to explore the impact of habitat fragmentation on the species diversity of Davidia involucrata community,this study took 18 representative Davidia involucrata communities in Sichuan Province as the research object,investigated and analyzed the plant species diversity in the community,and selected the species richness(R),Simpson Dominance Index(D),Shannon-Wiener Diversity Index(H)and Pielou Uniformity Index(J)are four species diversity indexes for research.Taking the average value of the coordinates of each sample as the center,10 circular buffers with a radius of 200-2000 m were set respectively,and 8 landscape scale level indexes were selected.The single-factor analysis of variance,Pearson correlation analysis and the Partial least squares regression analysis was conducted to discuss the change of landscape index at different spatial scales and the response of species diversity to habitat fragmentation.Got the following main results:(1)There are abundant species of Davidia involucrata community on the edge of Sichuan Basin.A total of 402 plants appeared in the community vegetation,belonging to246 genera of 110 families.Among them,there are 123 species of arboreal plants belonging to 90 genera of 48 families;113 species of shrub layer plants belonging to 74 genera of 40 families;166 species of herbaceous plant plants belonging to 126 genera of72 families.The species diversity of the tree layer,shrub layer and herb layer varies greatly,and the species composition of the tree layer,shrub layer and herb layer varies significantly among communities.(2)One-way analysis of variance showed that the PD,ED,IJI,SHEI,and CONTAG indexes did not differ on various spatial scales.The LPI index is significantly different from the 800-2000 m spatial scale on the 200 m spatial scale,the LSI index is significantly different from the 600-2000 m spatial scale on the 200 m spatial scale,and the SHDI index is different from the 1200-2000 m spatial scale on the 200 m spatial scale.Significant differences.As the spatial scale becomes larger,the mean value of the LPI index shows a clear downward trend,and the mean value of the LSI index and the SHDI index shows a clear upward trend.(3)Correlation analysis shows that at different spatial scales,the species diversity index of the tree layer is significantly related to the LSI index,PD index,and ED index in the landscape index,and there is almost no significant correlation with the remaining indexes;the species richness of the shrub layer It is mainly related to the LSI index,PD index,and ED index in the landscape index.The other species diversity indexes of the shrub layer are almost not significantly related to the landscape index;the species diversity index of the herb layer is almost not significantly related to the landscape index.The correlation is affected by the spatial scale.The correlation coefficient of the tree layer shows a certain regular change with the increase of the spatial scale,and the correlation coefficient of the shrub layer and the herb layer shows no regular change with the increase of the spatial scale.(4)Partial least squares regression analysis shows that some landscape indices at the spatial scales of 200m-800 m and 1400m-1600 m affect the species richness,Simpson dominance,and Shannon-Wiener diversity of the tree layer;at all ten scales,the selected landscape index None of them can explain the Pielou uniformity of the tree layer;at the spatial scales of 200-800 m and 1400-1600 m,the fragmentation of the habitat affects the species diversity of the tree layer of the Davidia involucrata community.At all ten scales,part of the landscape index plays an important role in the change of the species richness of the shrub layer,but the selected landscape index can hardly explain the Shannon-Wiener diversity,Simpson dominance,and Pielou uniformity of the shrub layer;At a spatial scale,the fragmentation of habitats affects the species richness of the shrub layer of Davidia involucrata community.Some landscape indices at the 200 m spatial scale affect the Shannon-Wiener diversity,Simpson dominance,and Pielou uniformity of the herb layer;at all ten scales,the selected landscape indices cannot explain the species richness of the herb layer;at 400-2000 m On the scale,none of the selected landscape indices can explain the Shannon-Wiener diversity,Simpson dominance,and Pielou uniformity of the herb layer;at the 200 m spatial scale,the fragmentation of habitat affects the species diversity of the herb layer of Davidia involucrata community. |
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