| Semi-humid evergreen broad-leaved forest is the representative of the subtropical evergreen broad-leaved forest in China,but also is the ecological barrier in the cnetral of Yunnan.In this paper,we studied the structure and stability of the semi-humid evergreen broad-leaved in the the cnetral Yunnan.It can provide an important theoretical basis for maintaining the biodiversity and the agricultural forestry industry in the area.During the period from March,2015 to March,2017,the semi-humid evergreen broad-leaved forest community and soil seed bank were investigated and cultivated respectively.According to the principle of typical sampling,10 samples(20m×20m)were set up,and four 5m×5m samples were also set up at four corners of each quadrant to investigate shrub layer,herb layer and tree plant regeneration layer.In accordance with the characteristics of dominant species or constructive species,the semi-humid evergreen broad-leaved forest in this area was divided into Castanopsis delavayi community,C.orthacantha community and Lithocarpus confinis community.Analysis of the structure of the three communities,species niche and interspecies,regenertation layer,soil seed bank and community stability,the results are as follows:(1)Species composition and structure of communities:There were 89 species,belonging to 33 families,62 genera in 10 samples,and the plant community hierarchical structure was obvious.The results showed that the plant community was in the growth stage.Compared with other evergreen broad-leaved forests,the area has low species diversity.(2)Species niche and interspecific association:In the communities,the niche breadth of Fagaceae is larger,mainly located between 1.3980~2.7930.They are widely constructed,having significant advantages in the utilization of environmental resources.The significant level of species is low.The dominant species of C.delavayi,C.orthacantha and L.confinis were weakly correlated with the general species.(3)Regeneration of communities:A total of 1398 plants of tree seedlings were recorded in the communities,there being 22 species,belonging to 6 families,15 genera.The seedling species of C.orthacantha community was the highest,having 17 species,and the density was(0.20±0.22)plants/m~2.There were 14 species of tree seedlings in the L.confinis community,and the density was(0.17±0.46)plants/m~2.There were only 11 species in C.delavayi community,with the density was(0.09±0.16)plants/m~2.The seedling density of tree plants in the community was negatively correlated with the area of chest height and shrub layer coverage,and there was no significant correlation with the coverage of herbaceous plants.(4)Soil seed bank:There were 69 species of seedling in the soil seed bank,and the similarity of the plant was similar to that of the herbaceous plants,which was only 10.13%.(5)The stability of plant community:the method of principal component analysis and M.Godron stability were quantified by mathematical method,combining with the diameter structure of the tree species in the community,we can see that the semi-humid evergreen broad-leaved forest community was in a more stable state in the Diaoling Mountain of Yunnan Province.The diversity of species had a certain effect on the stability of the community.The stability is the result of the interaction of multiple biological and abiotic factors in the community.There is no simple causal relationship between species diversity and community stability. |
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