哀牢山中山湿性常绿阔叶林不同干扰强度下土壤无机氮的变化

在云南哀牢山中山湿性常绿阔叶林地区，选取了木果柯原始林、栎类次生林和人工茶叶地3种群落类型代表人为干扰强度从小到大的梯度，研究了人为干扰强度对土壤NH4^+—N、NO3^-—N等特征的影响．结果表明，3种群落的土壤无机氮含量(0～15cm)存在显著差异：表现为随干扰强度增加，土壤有机质、全N降低，C／N比增高，NO3^-—N流失的潜力在增加，说明干扰不利于土壤肥力的保持和群落正向演替．同一群落类型下不同空间位置土壤的有机质、全N、C／N比、pH值和NH4^+—N基本一致，但NO3^-—N有较大变化，表明土壤中NO3^-—N的不稳定性．此外，NO4^+—N为无机氮的主要存在形式，约占无机氮总量的95.5％～99.2％

Dynamics of soil inorganic nitrogen in middle mountain moist evergreen broadleaf forest under different disturbance intensities in Ailao Mountain

The effects of three different intensities of disturbance on soil NH4(+)-N and NO3(-).N contents were studied in three community types (primary Lithocarpus xylocarpus forest, secondary oak forest, and tea plantation, which represent three different intensities of disturbance). The results showed that the contents of inorganic nitrogen in soil (0-15 cm) of three community types had marked differences. Soil organic matter and total nitrogen decreased, while C/N ratio increased, with the increasing intensity of the disturbance. Simultaneously, the potential lose of NO3(-)-N increased. It suggested that the disturbance was not in favor of the retainment of soil fertility and the positive development of community succession. The soil organic matter, total nitrogen and C/N ratio were basically same at different spatial sites in same community, while the NO3(-)-N contents were obvious difference. This implied that soil NO3(-)-N content was less stable than NH4(+)-N. In addition, NH4(+)-N was the major component of the soil inorganic nitrogen, accounted for 95.5%-99.3% of the total content of soil inorganic nitrogen.