Study On Quantitative Ecology Of Vegetation In The Upper And Middle Reaches Of Fenhe River Watershed,Shanxi

As the second largest tributary of Yellow River,Fenhe River is one of the important components in Shanxi rivers.Fenhe River watershed is the center of population and economic,distributing the rich wetland resources and developing abundant biodiversity.Based on the investigation on the vegetation in the upper and middle reaches of Fenhe River watershed,the the plant community composition,distribution,plant function groups,? diversity and the relationship between the habitats were studies by using ecology methods including numerical classification,ordination,Fisher's exact test,Spearman's rank correlation and Jaccard index.The aim of this study expected to present some scientific and theoretical basis for the biodiversity conservation and management of plant communities in Fenhe watershed.53 plant community plots in the upper and middle reaches of Fen he River watershed were classified into 13 associations by TWINSPAN and the ordination by DCA,which were Ass.Lemna minor,Ass.Typh a angustifolia,Ass.Calamagrostis pseudophragmites,Ass.Hippophae rha mnoides-Poa annua,Ass.Poa annua-Glycine soja,Ass.Polygonum hydropi per,Ass.Cyperus fuscus-Scirpus triqueter-Polygonum lapathifolium,A ss.Typhaorientalis-Scirpus triqueter-Phragmites australis,Ass.Hippopha e rhamnoides-Rosa xanthina-Carex lancifolia,Ass.Larix principis-ruppre chtii+Pinus tabuliformis-Rosa bella + Lonicera chrysantha-Carex lancifolia,Ass.Quercus wutaishanica-Spiraea pubescens-Carex lancifolia,A ss.Picea meyeri+Picea wilsonii-Lonicera hispida-Carex lancifolia and Ass.Larix principis-rupprechtii-Poa nemoralis.The results of DCA ordination showed that the distribution of species were similar with plots,and the leading factors effecting the distribution of the association s in this region were elevation and moisture condition.The mesophyte were distributed in higher altitude of the mountains,the lower altitude distributed hygrophilous plants.The hydrophyte and hygrophyte communities were distributed in the areas with good moisture conditions,and the mesophyte were distributed in the areas with poor moisture conditions.The plant functional groups(PFGs)in the upper and middle reaches of Fenhe River watershed were analyzed by Spearman rank correlation,Fisher's exact test and TWINSPAN.The results showed that:(1)Based on the results of Fisher's exact test,268 species-pairs had a positive association coefficient,of which 42 species-pairs had significant positive association(P<0.05)and 97 species-pairs had highly significant positive association(P < 0.01).Besides,there had 473 species-pairs had negative association,of which 48 species-pairs had significant negative association(P < 0.05)and 39 species-pairs had highly significant negative association(P < 0.01);(2)Spearman's rank correlation had 368 species-pairs with positive association,of which 38 species-pairs had significant positive association(P<0.05)and 125 species-pairs had highly significant positive association(P<0.01).Besides,there had 473 species-pairs had negative association,of which 80 species-pairs had a significant negative association(P<0.05)and 45species-pairs had a highly significant negative association(P<0.01);(3)Basis on the results of the association of species as well as that of analysis of clustering,the species were divided into three PFGs: mesophyte PFGs,mesohydrophyte PFGs and hydrophilous PFGs.The distribution of PFGs was mainly dominated by the moisture.The measurement indicator of beta diversity for those plots was calculated by Jaccard index.The T?,P? and F? diversity patterns of the stands in the upper and middle reaches of Fenhe River watershed were calculated,respectively,and the correlation among the T?,P?,F? diversity patterns and spatial distance and habitat heterogeneity were analyzed.The results showed that:(1)With the increase of the distance of stands among the stands,the T?,P? and F? showed increasing trend on the whole,that is the distance of the community showed the attenuation effect.(2)The TP was the leading soil factor that influenced the T?,P? and F? in the sample areas(P<0.05);while the influence of p H,TOC and TN on the T?,P? and F? was significantel(P>0.05).(3)Because of the restrictions on spatial diffusion and the influence of habitat heterogeneity,the diversity of beta diversity among the stands had obviously difference,(T?: 0.66-1,P?: 0.42-0.85 and F?: 0.51-0.94).(4)Although the T?,P? and F? reflected different aspects of diversity,the relationship between them was higher significance(P<0.01).(5)Based on the T?,P? and F? diversity patterns and its relationship with the spatial distance and habitat heterogeneity,it suggested that the environmental factors and diffusion limitation jointly dominated the pattern of beta diversity,namely the construction mechanism of the community was jointly dominated by the ecological niche theory and neutral theory.