| Fujian province is situated at the southeastern coast of China.The scenic areas of Gushan Mountain in Fuzhou is situated at the easten suburbs of Fuzhou,the capital of Fujian province,and the back mountain of Fujian Agriculture and Forestry University is situated at the westen suburbs of Fuzhou.The communities of secondary forests of Pinus massoniana, Acacia confusa in the scenic areas of Gushan Mountain and the back mountain of Fujian Agriculture and Forestry University which have cetain representativeness are the stands recovered by several decades hillclosing afforest to some extent.The ecological characteristics of the secondary forests of Pinus massoniana,Acacia confusa were studied in the work,including species composition and flora of communities,analysis on leaf characteristics of communities,construction dynamic of communities,species diversity of communities,species abundance distribution of communities,stability analysis of communities,the fitting and assessment of species-area curves of communities,sampling technique of communities.The area of plot sampling in the communities of the communities of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou and the back mountain of Fujian Agriculture and Forestry University were 3600m~2.The site factors were investigated by the method of forest community investigation,and the species,individual number,D.B.H.,height,coverage of herbage and so on were recorded.The results were as follows:(1)There were 39 families and 77 species in the community of the community of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou,29 families and 77 species in the community in the back mountain of Fujian Agriculture and Forestry University,while 24 families the same and 20 families different.The vertical structure of each community is evident,which could be divided into tree layer,shrubs layer,herbage layer and lianas.Bacically,in tree layers,the shap of its tall trees were composed of Pinus massonianaand Acacia confusa.ln Gushan, Melastoma candidum and Smilax china were the dominant species of shrubs layer;Coptosapelta dijfusa,Celastrus orbiculatus,Dioscorea opposita and so on were in the lianas;Imperata cylindrica.,Lophatherum gracile,Cyrtococcum patens and so on were in the herbage layer.In the back mountain of Fujian Agriculture and Forestry University,Rhodomyrtus tomentosa,Rhaphiolepis indica,Litsea rotundifolia Hemsl. var. oblongifolia and Loropetalum chinense were the dominant species of shrubs layer;Morinda umbellata Linn.subsp.obovata was the only one species in the lianas;Dicranopteris linearis was the main species in the herbage layer.The floristic compositions were complex in the two communities,with 12 distributions of genus of seed plants.The pan-tropical was preponderant,and the seed plants originated mainly from the tropic. (2)The leaf characteristics of the plants in the communities of secondary forests of Pinus massoniana,Acacia confuse in the scenic areas of Gushan Mountain in Fuzhou and the back mountain of Fujian Agriculture and Forestry University were analyzed according to Raunkiaer system.Study showed that in the two communities,the dominant leaf size was mesophyll whose percentage was 44.2% and 50.9% respectively,followed by microphyll;entire leaves(54.5% and 62.3% respectively);simple leaves were dominant in leaf form and the percentage of those was 76.6% and 75.5% respectively;the dominant leaf characters was papery leaves (50.5% and 50.6% respectively),followed by coriaceous leaves.(3)The construction dynamic of each community was analyzed by the number of individuals,the number of species,the sharing degree and the community lost stable rate for D.H.B.class and highness class.Study showed that the number of individuals for D.H.B. class went with that of highness class in each community,from low-to-high-to-low changing process.The largest number of species for D.H.B .class in the communities of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou was in the first class.while for highness class was in the first and the second class.The largest number of species for D.B.H. class in the communities of secondary forests of Pinus massoniana,Acacia confusa in the the back mountain of Fujian Agriculture and Forestry University was in the first and the second class,while for highness class was in the second class.The sharing degree was from high-to-low changing process in each community.The dominant population lost stable rate of each community was positive,and the stable rate was high.The two communities were all in stable dynamic developing.(4)The species diversity of the communities of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou and the back mountain of Fujian Agriculture and Forestry University was measured by importance value,species number,richness index,Shannon-Wiener and Simpson indieces,Shannon-Wiener and Simpson eveness indices.The results showed that the species of the community of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou were more.In general, the species of shrubs layer was more than that of tree layer;the species of tree layer was more than that of lianas;the diversity indieces of shrubs layer were higher than that of tree layer.Pinus massoniana,Acacia confusa were important in the structure of the species in the twocommunities.(5)The log series model is used to calculate and inspect the species abundance distribution of communities of the communities of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou and the back mountain of Fujian Agriculture and Forestry University.The results showed that species abundance of both tree layer and shrubs layer of the two communities obeyed a logarithmic series distribution,which suggested that each community was relative well,and its stability was fairly good,its biodiversity was fairly high.(6)The stability of the communities of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou and the back mountain of Fujian Agriculture and Forestry University was studied by Zheng yuanrun's M.Godron method,and a modified model was presented.The results are more precise and effective.The two communities were in the unstable state.Human disturbance was an important factor,and that it was not a easy task that that they needed the long-term protection.(7)The fitting and assessment of 10 species-area curve models of the communities of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou and the back mountain of Fujian Agriculture and Forestry University were studied and their applicability wasexamined.The results showed that model (30) (S = aA~b) and model (27) (S=[b+alog(A)]~c)were thebest models to modify the two community species-area relationships,while model (28) (S=alog(A+1)) was the worst one.The study laid a foundation for estimating the species number and studying the critical sampling area.(8)The critical sampling area for the communities of secondary forests of Pinus massoniana,Acacia confusa in the scenic areas of Gushan Mountain in Fuzhou and the back mountain of Fujian Agriculture and Forestry University were studied basing on the parameters of 10 species-area curve models having been modified and the species number having been estimated.The results showed that the critical sampling area by the 5 methods were different from one to anotherm and that method 1 could be understandable,intuitive and definitive and the critical sampling area calculated by it were optimum.and that the results calculated by the other methods were of low reliability,and that the critical sampling area calculated by method 1 for the two communities were respectively 3023m~2 and 3416m~2 when the proportional factor was 0.95.
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