Influence Of Under-forest Economic Models On Vegetation And Soil In Karst Mountain In Southwest China

The article from the plant diversity, physical and chemical properties, microbial quantity of the soil and other as pests studies systematically the change of vegetation and soil ecological characteristics in southwest Karst Mountain. The results are as follows.Almost all the vegetation abundance is decreasing under the forest economic mode. In the six forest economic modes, the largest is under the mode of grass cultivation in Ficus lacor, the least is the mode of Dendrocalamus latiflorus. About under the mode of poultry feeding in D. latiflorus, the pattern is over than the contrast diversity index of Simpson and Shannon.But the other five modes is opposite. As to the evenness index of Pielosu, The contrast is over than the pattern in the six modes. Dominance index of Alatalo is the largest under the mode of domestic animal in Pinus massoniana, the opposite mode is under the mode of grass cultivation in F. lacor. About the similarity index of Jaccard and Sorenson under the two modes of D. latiflorus, the pattern is equal to the contrast and the lowest similarity index reach to the top1.0. The lowest similarity index is under the mode of poultry feeding in Eucalyptus robusta. The similarity index of Jaccard is0.15and Sorenson is0.27. The largest diversity threshold is under the mode of grass cultivation in F. lacor whose value is2.4, it belongs to the third category. The lowest is the mode of D. latiflorus, whose value is0.7, it belongs to the forth category.Concretely speaking, the organic matter increased largest in under the mode of fungi cultivation in E. robusta and under the mode of poultry feeding in D. latiflorus. The content of total nitrogen, available nitrogen and available potassium increased largest under the mode of domestic animal in P. massoniana, while total phosphorus increased largest under the mode of fungi cultivation in E. robusta. While total potassium increased largest in under the mode of poultry feeding in D. latiflorus. As for the amount of microbial in the soil, the largest number is under the mode of poultry feeding in E. robusta. On the contrary, under the mode of fungi cultivation in D. latiflorus is the least. So, microbial amount has a positive correlation to the organic matter, available phosphorus and available nitrogen.The study showed significant differences in soil infiltration among different under-forest economy modes and soil layers. Infiltration was highest (449mL) in0-10 cm soil layer under the mode of fungi cultivation in D. latiflorus forest. The second highest (427.5mL) was under the mode of grass cultivation in F. lacor forest, followed the soil under the mode of poultry feeding in D. latiflorus forest (389.4mL). Soil infiltration was poorest (241.5mL) under the mode of fungi cultivation in E. robust a forest. Soil infiltration in each under-forest economy mode decreased with increasing soil depth. The common infiltration model was the most suitable for simulating soil infiltrating processes in the study area, followed by the Kostiakov equation, and then the Horton equation. Soil infiltration evaluation via correlation analysis showed that the strongest soil infiltration capacity was of the mode of fungi cultivation in D. latiflorus forest. This was followed by the mode of grass cultivation in F. lacor forest and then poultry feeding in D. latiflorus forest. Fungi cultivation in E. robusta forest performed the least in terms of soil infiltration. Correlation analysis between soil infiltration and physiochemical properties showed significant positive correlation between soil infiltration and organic matter (β1), moisture content (β2), total soil porosity (β3) and the0.005-0.01mm soil particle content (β6)(P<0.01). Also significant negative correlation existed between soil infiltration and soil bulk density (β8) and0.05-0.25mm particle content (β5)(P<0.01). According to the correlation analysis, eight indexes of soil physiochemical properties (which significantly influenced soil infiltration) were noted. Comprehensive parameters of soil infiltration (a) and soil physiochemical properties (β) were obtained by the Principal Component Analysis. Then linear regression models of the indicators of soil infiltration and comprehensive parameters (a and β) were built as a=0.249α1+0.254α2+0.252α3+0.254α4, β=0.167β1+0.183β2+0.200β3+0.174β4-0.145/β+0.131β6+0.106β7-0.200β8. In the models, a, was initial infiltration rate, a2was stable infiltration rate, α3was average infiltration rate,α4was total infiltration;β4was non-capillary porosity,β7was content of0.001-0.005mm soil particles.The result of the research shows that choosing appropriate forest stand and forest economic mode is very important to improve the permeability of soil and increase the amount of soil microbial and nutrient content in the development of forest economy. At the same time, the result is necessary to improve the soil productivity and guide the stability of the forest economic ecological system, which promotes a healthy and orderly development of forest economy.