| Recent years lots of poplar plantations have been established in the upland area. However, pool soil conditions are the main factors to affect poplar growth. In order to improve the soil properties and increase the productivity of poplar plantations in this area, biological mulching treatments were designed in Guizhou province. Tow treatments were arranged in this experiment, e.g. mulching thickness(four levels:0.0, 2.5, 5.0 and 7.5kg/m2 with mixed muching material) and four material (Coriaria nepalensis, Quercus fabri, Imperata cylindrical var. major and Pteridium aquilinum var.latiuscukum with muching thickness of 5.0kg/m2). The one-year results are as follows: 1.Decomposition rate of four different species of material was in the rank of Coriaria nepalensis>Quercus fabri>Imperata cylindrical var.major>Pteridium aquilinum var. latiuscuk-um, while release rate of eleven mineral elements(N,P,K,Ca,Mg and so on) showed trend of Coriaria nepalensis>Quercus fabri>Imperata cylindrical var.major>Pteridium aquilinum var. latiuscukum. 2. Soil organic matter, N,P and K contents, especially available nutrient, obviously increased after mulching. upmost nutrient contents were found in the treatment with 7.5kg/m2 mulching; nutrient contents of different mulching material: the first is Imperata cylindrical var.major,the next are Quercus fabri, Coriaria nepalensis and the last is Pteridium aquilinum var.latiuscukum. 3. Mulching maked soil moisture increase, soil bulk density decrease and soil temperature stabilize. With the increasing of mulching thickness, its ameliorative function was strengthened; the effect of Pteridium aquilinum var.latiuscukum was a little better than other vegetation in different mulching material. 4. After mulching, activities of soil microbes were enriched and soil pH value was regulated with tending to neutralization gradually. With the increasing of mulching thickness, the amount of soil bacterium and fungi were increased, the regulative function of pH value was further intensified; for different mulching material, the biggest amount of fungi was observed in the treatment with mulching of Quercus fabri, the amount of bacterium are most in Imperata cylindrical var.major. However the regulative function of pH value is maximal in Pteridium aquilinum var.latiuscukum. 5. Mulching heightened the nutrient concentrations of poplar leaves. Upmost nutrient concentrations in leaves were found in with mulching of the 7.5kg/m2 treatment, There were significant differences in the K, Mn and Zn concentrations between treatment; for different mulching material, the concentration of K was the highest in the treatment with mulching of Pteridium aquilinum var.latiuscukum, Mn and Zn in Quercus fabri, N,P,Ca ,Mg and so on in Coriaria nepalensis. 6.The growth of poplar plantation was improved after mulching. With the increasing of mulching thickness, increment of tree heigh and DBH increased. Compared to the control, the increment of tree heigh and DBH in the treament with 7.5kg/m2 mulching, was about 45.59% and 91.44% higher respectively; for different mulching material treatment, the increment of tree height in the treatment with Coriaria nepalensis, Quercus fabri, Imperata cylindrical var.major and Pteridium aquilinum var.latiuscukum was 82.34%, 46.80%, 38.90% and 6.76% higher than the control respectively; while the increment of DBH was 114.37%, 74.81%, 68.16% and 65.43% higher than the control respectively. 7. Based on the one-year results of study, we suggest biological mulching can improve the soil properties and growth of poplar plantation in the upland area. However some difference were observed in various mulching thickness and different mulching material. Best growth increament were found in the treatment with 7.5kg/m2 mulching for mulching thickness, while best growth increament was observed in the treatment with Quercus fabri, Imperata cylindrical var.majoris, More researches are needed in order to identify which treatment is best for improve growth and properties. |
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