Synergistic And Evolutive Reserch Of Vegetation And Soil At Typical Ecosystem In Karst Peak Cluster Depressions

Depressions between hills in Karst located in the southern sloped area in southwest, an area about9.7km2, with highly landscape heterogeneity, a fragile ecological environment, lean soil, serious soil erosion, and violent contradiction between human and land. Its flora belongs to Pan Arctic flora and China-Japan forest flora, Category of Dian/Qian/Gui, and the Non-Regional climax community is evergreen and deciduous and broad-leaved mixed forest. Degradation in varying degrees happened under human disturbance, some partial way and different succession stage communities and ecosystem are emerged to consist a coexistence pattern. This article is based on quadrat setting and a comprehensive research and analysis on vegetation and soil for total6kinds of typical ecosystems in Karst peak cluster depressions (sloping farmland, grass, shrubs, plantation, secondary forest, and primeval forest), build three20m X20m quadrat in2representative community, analysis the community character and difference of plant community and soil fertility in typical ecosystem in Karst peak cluster depression with multiple comparison analysis method, discussed the main impact factor by principal component analysis and declared the coupled relationship between vegetation and soil with canonical correlation analysis of fragile ecosystem in Karst peak cluster depressions. The article is looked forward to provide a theoretical basis for restoration and reconstruction vegetation in this area and the entire Karst region. The main conclusions are as follows:(1)Community characterisitics of different ecosystems in Karst depression are different, the community types increase gradually along the slope of sloping farmland, grass, shrubs, plantation, secondary forest, and primival forest. It is generally believed that stability is closely related to plant diversity, climax community is the most stable one, but in Karst depression, to family, genus, species, family with important value>10, species with important value>5, and species diversity, the max value of them appears in the secondary forest, the best value of community structural appears in the climax community primeval forest. It shows that plant diversity is only the basis or necessary condition of community stability, and this stability is more reflected on rationality of structure.(2)Temperature and humidity conditions in Karst peak and depression is quiet good, on the one hand this caused strongly soil eluviations, the soil is slightly acidic or alkaline, PH value is between6.60-7.75; on the other hand, it is highly conducive to biological reproduction and growth, the function of biological "self-fatten" is very intensive. Compared with laterite on the same latitude, soil in Karst contains highly nutrients. The highest contents of organic matter, total nitrogen, total phosphorus, total potassium, alkaline hydrolytic N, rapidly available P, rapidly available K, appears respectively in follow community:primeval forest and secondary forest, primeval forest, sloping farmland, sloping farmland, primeval forest, primeval forest, shrub. The Lowest value appears respectively in plantation and sloping farmland, plantation, grass, plantation, sloping farmland, shrub, sloping farmland. Therefore, organic manure and N fertilizer shall be used more in sloping farmland, P fertilizer shall be used more in grass and shrub, N fertilizer shall be used more in plantation. Secondary forest and primeval forest are mainly to maintain the relation between vegetation and soil.(3)In soil of Karst peak and depression, the nutrients, except Ca and Mg, are obviously lower than average value of world and zonal laterites on same latitude. And its total capacity is quite small with serious lack of mineral nutrients, while this limits the growth of plants, it becomes the important reason of rocky desertification also.(4)In soil of different ecosystems of Karst peak and depression, quantity and composition are different with the content of microbial biomass carbon, C, N and P, but highest values are both in primeval forest. In the composition of microbial population, actinomycetes take a larger proportion in sloping farmland, grass and shrub. Bacteria take a larger proportion in three forest ecosystems. C-N radio, between1.04-7.02, is very small, the highest number appears in grass and sloping farmland, soil microbial biomass Carbon do a well fractal relation with fungi, bacteria, and actinomycetes.(5)In different ecosystem of Karst pesk and depression, the mainly impact factors are different. To the entire region, the relationship between vegetable and soil is quite comples. The dominant factor is diversity factor group of shrub. It means the cultivation and protection of shrub shall be strengthen, and bring it to play its role to be a connecting link in the community succession and community spatial structure.(6)In Karst peak and depression, there is a typical relation between two part of vegetable, soil nutrients, soil mineral nutrients, and soil microbes. N, K, Si and microbial biomass carbon do a most close relation with plant diversity, soil nutrients and Si do a most mutual influence, organic matter, microbial biomass carbon, soil mineral nutrients and microbial biomass P interact each other strongly. From the relation between vegetation and other factor, it is found that N, Ca, Mg and fungi strongly influence the distribution of plant diversity.(7)In Karst peak and depression, cluster analysis can divide6typical ecosystems into4development types. Plant community characters and soil quality in different type are different also.