Characteristics Of Conyza Canadensisis Community In Linfen

Conyza Canadensis is a invasive alien species,which is widely distributed and has serious damage.It has caused damaged the ecological environment to our country's and has had a serious impact on the biological diversity of the local ecosystem.This article has probed into the Conyza canadensiscommunity in the Linfen of Shsnxi Province and studies the classification,sequenencing,species diversity,functional groups and ecological niches ofthe Conyza canadensiscommunity with plant geography and quantitative ecology.Our purpose is to provide basic data to control the expansion within the arid region.The resulted showed that:(1)A total of 84 species were found in 105 sample plots of the field survey made in the Linfen,and they belong to 25 families and 62 genera.which include 70 families of dicotyledonous,accounting for a percentage of the total 83.33%,and 14 families of monocotyledons,accounting for a percentage of the total 16.67%.Compositae(28 ?),Gramineae(9 ?),Chenopodiaceae(6 ?),Leguminosae(6 ?),Labiatae and Polygonaceae(4 ?).The type of distribution was diverse.There are 8 distribution types and 4 variants.In the analysis of family,the worladwide distribution type was predominant,accouting for 88% of the total families.As for genus,the temperate distribution type accounted for 45.90%,while the worldwide distribution type accounted for 25%,revealing the obvious temperate characteristic of this area.(2)The minimum variance clustering was applied to the Conyza canadensis communityquantityclassification.Basedon the 105 quadrats dataset,the Conyza Canadensis community was classified into 6 associations,and the basic characteristics of those associations were discussed.The redundancy analysis(RDA)was applied to the Conyza Canadensis community combined with total nitrogen?TP?TK?RAN?RAP?RAK?SWC?pH?SOM nine soil environmental factors,environmental factors just accounted for 6.93% of the community species distribution.Based on Monte CarloPermutation Test,the bimultivariate redundancy statistic of environmental factors were accepted,but it didn't mean that every environmental factor was significant to the species distribution.The first axis of RDA mainly reflected the change of RAN,which ascended from left to right.The second axis mainly reflected that the RAK was getting greater from the bottom to the top,while the content oforganic matter is gradually dropping.Results showed that the changes in RAN?RAK were the important ecological factors affecting the composition and distribution of the Conyza canadensis community species in Linfen.(3)The species diversity of the 6 associations of the Conyza canadensis community were studied by using Patrick richness index(R0)? Margalef richness index(R1)? Simpson ecological dominance index(?)?Shannon-Wiener diversity index(H)?Pielou evenness index(E1)?Alataloevenness index(E2).The results showed that:the species diversity indexes of R0 ? R1 ? ? ? H ? E1 were consistent,and the Simpson ecological dominance is inversely proportional to them,but Margalef richness index is more advantageous.Richness index,diversity index and evenness index are significantly and positively correlated with each other;The analysis on the relationships between the diversity of species and soil environmental factors shows that the species' diversity of the Linfen is mainly restricted by the contents of soil available nitrogen,availablepotassium,available phosphorus.(4)By using the survey methodology of community ecology,a total of 105 sampling plots were installed in Linfen of Shanxi.According to the species occurrence frequency and importance values of the investigated herbaceous species,27 dominant species were selected for interspecies association analysis.The associations between dominant species were determined based on the ?2inspection and in light of the association coefficient(AC)and the percentage cooccurrence(PC)and plant functional types(PFTS)were defined according to interspecific associations and cluster analysis of the dominant species by R.Overall,the 351 species pairs formed by the dominant species showed positive association,but the vast majority of the species pairs showed weak association and non-association.Seven herbaceous plant functional groups were classified,with the same resource utilization ways and ecological requirements of the species in each group.(5)The article has probed into the niche breadths and niche overlaps in the Conyza Canadensis community vegetations of Linfen with Shannon-Wiener niche breadth index and Lenvins niche overlap index.Results show that the niche breadths of Conyza canadensis ?Setariaviridis ? Humulusscandens and Tripoliumvulg are are widest,which shows that the niche breaths of species are related with their distribution ranges.According to an analysis on overlap indexes,the niches of the dominant species of Linfen are not completely overlapped with each other,which is the differences in their environmental resources using.The widerspecies' niche breadths are,the wider the niche overlapsare,just as Setariaviridis ?Humulusscandens and Tripoliumvulgare.