The Nitrogen Repository Spatial And Temporal Changes Of Typical Forest Types Soils On Eastern Slope Of Gaoligongshan Mountains

Nitrogen is essential element for plant, most studies focused on a single type of forest vegetation or a certain period of time on farmland at present, but the spatial and temporal heterogeneity, nitrogen cycling of different forest vegetation types soil remain largely unknown. It is a great significance for scientific operation and management of ecosystem, degraded ecosystem restoration and response to global climate change that how to clarify different forest vegetation types of spatial and temporal heterogeneity of soil nitrogen cycle.Soil nitrogen in forest ecosystems have obvious heterogeneity affected by altitude and time. As altitude increases the forest vegetation types and soil nitrogen showed obvious vertical distribution zones on the same altitude. In order to reveal the spatial and temporal heterogeneity of soil nitrogen cycling of different types of forest vegetation, and reducing the influence caused by human, We chose the study sites in Gaoligongshan Mountains Nature protected areas,1 year cycle, using the in-situ positioning technology to study the spatial and temporal variations of soil nitrogen of five typical forest vegetation types in Gaoligongshan Mountains eastern slope, which are Dry-Hot Vally(783m), Montane Rain Forest(1430m), Monsoon Evergreen Broad-leaved Forest(1490m), the Mid-Montane Humid Evergreen Broad-leaved Forest(2390m), Tsuga Forest(2920m). In order to provides scientific basis for operation and management ecosystem, degraded ecosystem restoration, response to global climate change, and better protect the biodiversity of Gaoligongshan Mountains Nature Reserve. It also provide theoretical basis for the scientific, efficient and economic development and utilization of Gaoligongshan Mountains forest resources. The main results were as follows:1.The total nitrogen, hydrolyze nitrogen content increases with the altitude; The content of nitrate nitrogen is gradually reduce with the altitude; Ammonium nitrogen content have no obvious change with altitude, but the content obviousincreased in 0-20 cm depth soil of the 783 m-1490 m. Different types of forest soil of various forms of nitrogen content showed obvious vertical distribution in different soil depths.2. In the same forest types (altitude) of soil total nitrogen, hydrolyze nitrogen, nitrate nitrogen content changes with the seasons (summer-autumn-winter-spring-summer), present "rise-reduce-higher-" the trend of the rule of changes over time is significant.3. The net nitrogen mineralization of different forest types soil in 0-20 cm in autumn and spring season, the soil mineral nitrogen accumulation content increases, The soil mineral nitrogen decomposition lead to the content reduce in summer and winter season,4. The soil nitrogen mineralization of different forest types increase with the altitude.5. The nitrogen mineralization rate increase with altitude has a increase tendency of different forest types soil in 0-20 cm; nitrogen mineralization rate in 0-20 cm is more than 20-40 cm...