| Kunming University of Science and Technology; Ecology; SHI JianhuaBy the field investigation and laboratory analysis methods, the study inlvolved typical and common plant Pinus armandii forest, combined with a certain years of the Bushwood and Abandoned Land in the central Yunnan, formed of a couple of vegetation recovery sequence:wasteland-bushiness-woodland-secondary forest. Through research the communities soil of Yunnan Karst areas of mechanical composition, soil aggregates, soil nutrients,water features and microbiological characteristics to understand the soil fertility coefficient. As a theoretical and reference for the central Yunnan plateau and the Karst areas all of China of practice and optimization of vegetation recovery mode. The results were as follows:1. Composition of the mechanical of particles in the soil profile, the<0.05mm of particles took the largest size, it indicated that a small proportion of gravel and sand in the soil, and it did not show a certain regularity. Soil bulk density in each soil layer as follows:0-20cm, Abandoned Land> Bushwood> Pinus armandii secondary forest> Pinus armandii woodland;20-40cm, Abandoned Land> Bushwood> Pinus armandii woodland> Pinus armandii secondary forest and the bulk density ranged from0.95to1.36g.cm-3, that was beneficial to plant growth and recovery.2. Soil porosity showed that Pinus armandii woodland> Pinus armandii secondary forest> Bushwood> Abandoned Land, on the whole tended to increase with plant roots. In addition, the capillary porosity is a part of the total porosity of soil, the distribution space often has important links with the soil total porosity, its distribution in various communities and total porosity higher degree.3.After wet-sieving method, the aggregate's particle size>5mm content ranged from2.31%to31.48%, while by dry-sieving method,>5mm aggregate content ranged from23.98%to61.10%, the soil aggregates by wet sieving was significantly lower than by dry sieving. The destruction rate of soil aggregates in sequence Abandoned Land> Bushwood> Pinus armandii woodland> Pinus armandii secondary forest, as structural damage to the smaller rate, the corrosion resistance stability tends to more stable; Waterstable aggregate of soil had the larger size distribution of the order:Pinus armandii secondary forest> Pinus armandii woodland> Bushwood> Abandoned Land, With the recovery of the surface plant, it favorable of forming the larger particle waterstable aggregates;Bushwood and Abandoned Land had a higher content of small particle size in waterstable aggregate, if it took advantage of small particle size in waterstable aggregate, it could display the corrosion resistance got weaker; with the community recovery from low to high, the difference of content in waterstable aggregate were close to each other, so its corrosion resistance would be stronger. Organic carbon content of soil aggregates in Abandoned Land was the lowest, which was to fewer litter cover on its surface. In addition, the organic carbon content of the lower soil profile was largely affected by the downward migration of the upper domination, the organic carbon content is from top to bottom progressively decreasing.4.The pH of soil in the different communities<6.5, it was due to the surface litter by decomposition effect to produce lots of organic acids. In addition to Abandoned Land, on the surface of others the litter decomposition to increase organic matters, because of the gravity which leaded to in0-20cm the content of soil organic matters were higher than in20-40cm soil layer. In the soil profile, the distribution and content of total nitrogen was similar to soil organic matters, available nitrogen and total nitrogen content in the soil had a well correlation.In the soil profile, the content of total phosphorus and available phosphorus were not showing a certain law. And in the upper soil profile the content of total potassium would be lower than the underlying soil. While potassium appeared the opposite of growth, indicating that the absorption of plant available potassium was larger focused on the soil surface.5. The mean value of soil C/N in different soil profile had a significant difference, between0-20cm the soil organic carbon content was greatly higher than the20-40cm soil layer, so that the mean higher than the lower soil profile. With the type and quantity of the microbial flora and its community recovery time increased in the circulation, it was beneficial to the flow of the carbon and nitrogen in the soil profile. 6.At the first moment, permeation rate had got to increase and then tend to decrease, and ultimately it achieved a steady state. To achieve steady infiltration state, the Abandoned Land took the shortest time about25min, and Pinus armandii secondary forest had the fastest penetration speed to reach the steady infiltration stage of2.782mm/min. The ability to penetrate in the soil of the recovery of communities as follow the order of Pinus armandii secondary forest> Bushwood> Pinus armandii woodland> Abandoned Land.In0-20cm soil layer, the percentage of saturated water content got the sequence of Pinus armandii secondary forest> Bushwood> Pinus armandii woodland> Abandoned Land, and the capillary moisture took the same trend as it. Hygroscopic water made the change to Bushwood> Pinus armandii secondary forest> Pinus armandii woodland> Abandoned Land. In20-40cm soil layer, the percentage of saturated water content got the sequence of Bushwood> Pinus armandii secondary forest> Pinus armandii woodland> Abandoned Land, the capillary moisture took consist in hygroscopic water;Soil water storage with the relevant of the surface coverage of the litter, soil water storage follow the order of Pinus armandii secondary forest> Bushwood> Pinus armandii woodland> Abandoned Land. Surface runoff and the amount of soil loss in different communities were:Abandoned Land> Pinus armandii woodland> Bushwood> Pinus armandii secondary forest. It indicated that surface runoff and the amount of soil loss were consistent, namely that they were good at positively related with each other.7. The surface soil had a contain of microorganisms were as follows: Bushwood> Pinus armandii secondary forest> Pinus armandii woodland> Abandoned Land. In addition to Abandoned Land, in the other communities3types of microorganisms were bacteria> actinomycetes> fungus, it showed that from the Bushwood stage began with bacteria were the dominant species. In addition, the number of bacteria, fungus and actinomyces in0-20cm soil layer with total microbial counts did not show the expected law of them. But the three microorganisms had a significant correlation in relative ratio. 8. Combined with the equal right law and non equal right law to research the comprehensive soil fertility in the study area. If we just compare the soil fertility of the soil profile structure, it would be showed that the soil fertility of0-20cm soil layer's was slightly higher than the20-40cm soil layer; however, the soil fertility in both of them illstrated the unanimous variation, the order of them as follows:Pinus armandii secondary forest> Pinus armandii woodland> Bushwood> Abandoned Land. In summary, with the recovery of the surface plant, the soil fertility had improved significantly, that's to say, if the vegetation recovery period took longer, the soil fertility would be upgraded obviously. |
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