The Study Of Plant Community And Flora In Luzhi River Valley In Yunnan,China

This paper is based on the fields investigation,herbarium specimens collection and identification,data processing and analysis of river valley vegetation in the Luzhi River Basin,central part of Yunnan Province.A preliminary analysis of the vegetation flora and community species diversity was conducted and the main conclusions were:(1)There are total of 253 species of wild seed plants belonging to 211 genera and81 families(Flora of China)in the community plots,among which 9 genera and 13 species belong to 6 families of ferns,and 240 species belong to 75 families and 202 genera of angiosperms.(2)The seed plant of the Luzhi River basin is obviously subtropical in nature,showing a clear adaptation to the dry environment.There are 75 families of angiosperms,which can be divided into 6 distribution types and 3 variants.The 202 genera are divided into 14 types and 15 variants.(3)The Shannon-wiener index of the tree and shrub layer showed a trend of increasing at first and then decreasing the upstream.However,the trend of change is not significant.The Simpson diversity index was moderate in the upper and middle reaches,and a slightly lower comparing with the middle and upper reaches in the lower reaches near Sanjiangkou area.Tree species richness in the community of the valley in the Luzhi River basinis from no trees existed in the upper reaches to the richer in trees in the lower reaches.The vegetation type change from upper chaches to lower reches is from dry-warm shrub-grass with scarce tree,dry-hot shrub-grass with scarce tree,to monsoon forest.(4)Five plant community types were found in the survey,and I discovered that the major community types have changed through the time-scale comparison,Woodfordia fruticosa-Heteropogon contortus and Pistacia weinmannifolia-Heteropogon contortus appeared in this survey and did not investigate the community type of Caryopteris forrestii-Heteropogonetum contorti and Osysis wightinana-Cymbopogonetum distans that appeared in the 1989 survey records.in which the community types were the same but some of the major associated species were different.The quadrat DCA ordinationmap reflected that the disturbance gradient influenced the distribution of plant communities,while the quadrats and environmental factors CCA ordination map reflected that although elevation changes was the main factor of influence for community distribution,other environmental factors also influenced the vegetation distribution.In terms of the community distribution environmental factors,the height and total coverage of the community were negatively correlated with the elevation,which were also negatively correlated with the slope and aspect,but the correlation of these two environmental factors were not obvious.