Studies On The Relationships Between Species Diversity And Environment In Evergreen Broad-leaved Forests In Jinyun Mountain, Chongqing

1. The relationships between soil enzymatic activity and soil fertility in evergreen broad-leaved forests in Jinyun Mountain were studied by using Correlation Analysis. The results were as follows: Organic matter, total nitrogen, available nitrogen, available phosphorus and available potassium had close relationships between each other. Activities of catalase, invertase, acid phosphatase had close correlation with organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium. The activity of polyphenol oxidase had close correlation with organic matter, total nitrogen, and available phosphorus. Activities of different soil enzymes were closely correlated to each other. Activities of different soil enzymes can be used as an index to evaluate the fertility of soil in evergreen broad-leaved forests in Jinyun Mountain.2. Investigated communites were classified by using module of Ordination Axes Clustering(OAC) in Detrended Canonical Correspondence Analysis(DCCA).The results showed that:l.Elaeocarpus japonicus-Symplocos setchuanensis-Daphniyllum oldhamii; \\.Elaeocarpus japonicus - Symplocos setchuanensis-Gordonia acuminata; lll.Neolitsea aurata vai.glauca - Symplocos lancifolia - Gordonia acuminata ; IV.Engelhardtia roxburghiana-Symplocos setchuanensis-Gordonia acuminate. DCCA of plots showed: Community III and community IV were higher than community I and community II in soil water content gradient. Community IV and Community II were higher than community I and community III in activities of acid phosphatase and invertase gradients. In the content of organic matter, total nitrogen, available nitrogen, available phosphorus, available potassium, and activity of catalase gradients, community IV scored the highest and community I was the lowest. Community IV was situated on sunny slope and community I was situated on shadyslope in the respect of slope exposure. Community IV had higher slope inclination than community I. DCCA of species showed: Engelhardlia roxburghiana, hea macmphylla, Rhododendron stamineum, Castanopsis carlesii var.spinulosia, and Symplocos lancifolia were higher than other species along soil water content, content of organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium gradients. Gonlonia acuminate, Symplocos setchuanensis, Adinandra bockiana, and Castanopsis fargesiinity were intermediate along content of organic matter, total nitrogen, available nitrogen, available phosphorus, available potassium gradients, but were lower than other species along soil water content gradient.3. The variation patterns of species diversity in evergreen broad-leaved forests in Jinyun Mountain were discussed. The relationships between community diversity indexes and slope inclination and slope exposure were analyzed. Moreover, the relationships between soil factors and species diversity were analyzed by applying Detrcnded Canonical Correspondence Analysis (DCCA). It was found that: (1) In all 17 plots, herb layers had the highest species abundance,and tree layers had the highest species evenness. (2) With the increase of slope inclination, species diversity in tree layers increased first and then decreased, the species diversity in shrub layers decreased. For herb layers, Shannon-Wiener H decreased with slope inclination.but Simpson D increased first and then decreased. (3) Diversity and evenness indexes in tree layers of plant community at sunny slopes were higher than those at shady slopes. The species abudance,evenness and total individuals in slirub and herb layers at shady slopes were higher than those at sunny slopes. The differences between shady communities and sunny communities were not statistically significant. (4) Soil water content and available nitrogen obviously affected the species abundance and evenness of tree layers, available phosphorus had significant effects on the evenness of tree layers,no effects of total nitrogen and organic matter on the species evenness of herb layers were detected. (5) Polyplien...