Study On Soil Characteristics Of Several Different Forest Types In Changsha Urban-rural Ecotone

Ecotone is the transition zone between urban and rural areas with both urban and rural land-use nature, especially the rural areas, close to and with some of the characteristics of the city. As a result of great input of agricultural pollutant, solid waste and industrial "three wastes", the urban-rural ecotone has become the district, where land is highly and intensively used, and the succession of soil quality is ultimately strengthened.China's urban and rural economic development and the steady improvement of people's life quality have been intensely restricted by a series of problems, such as soil fertility decline in the urban-rural ecotone, the deterioration of environmental quality, the weakening of ecosystem functions, etc. There is certain research on urban and rural soil both at home and abroad. For the urban-rural ecotone, it focuses more on land-use planning than the soil fertility. Studying the pilot tree farm of Hunan Academy of Forestry in Changsha urban-rural ecotone, with a view to provide a theoretical basis for sustainable management of forest resources in the urban-rural ecotone, this thesis researches and analyzes soil enzyme and the physical and chemical properties of the five soil, and evaluates their fertility.1. The vertical differentiation law of soil physical properties is obvious. The soil bulk density differences in different soil layers of same stand was not obvious, and the bulk density essentially increases with soil depth; while capillary porosity, total porosity and natural water content basically reduce with soil depth.2. The vertical distribution law of soil chemical properties is clear. Chemical nature in different stands basically decreases with soil depth, and soil nutrient content in mixed forest is generally more than pure forest land.3. The five forest soil all reduce with soil depth. Synthetically, soil urease activity in mixed forests is more than that in pure forests, and broad-leaved forests more than coniferous forests. The order of soil enzyme activities is respectively Fir broad-leaved forest>Massoniana broad-leaved mixed forest> camphora forest> Pinus elliottii forest> Liquidambar forest.4. Based on separate content analysis of total nitrogen and available nitrogen, total phosphorus and available phosphorus, total potassium and available potassium in five stands of the pilot area, all the results show significant positive correlation. That is, the transformation of entire nutrients in the soil significantly affects the available nutrient supply. The activities of catalase, urease, phosphatase, dehydrogenase and cellulase in forest soils have strongly significant or significant positive correlation with the above six fertility factors. Therefore, the soil enzyme activity is more reliable to evaluate the forest soil fertility in urban-rural ecoton.5. The integrated soil fertility of the five stands in the pilot area has been evaluated through principal component analysis and amended Nemero (Nemoro) composite index. The two methods come to the order of integrated soil fertility coefficient:Massoniana broad-leaved mixed forest> Fir broad-leaved forest> Pinus elliottii forest> camphora forest> Liquidambar forest.The fertility levels of Liquidambar forest, camphora forest and Pinus elliottii forest are all "poor" (<0.833); those of Massoniana broad-leaved mixed forest and Fir broad-leaved forest both "general" (0.833≤P<1.667). According to standardized results of the amended Nemero (Nemoro) composite index method, we can see that the content of total nitrogen and available K are the main factors ofintegrated soil fertility level in the pilot area.