Forest nitrogen deposition of through fall in Linzhi of Tibet, China

The concentration of atmospheric nitrogen (N) deposition increasing significantly is a concern in Global change. Atmospheric nitrogen deposition is increasing interest. Most research on N deposition mainly focuses on sensitive natural ecosystems. Information on N deposition in important ecosystems such as the Qinghai-Tibet Plateau is scarce. Although we might expect less impact form anthropogenic deposition compared with other regions of China, the ecological environment there is fragile. Quantitative evaluation the atmospheric nitrogen deposition of through fall is important pathway to research the N cycling into forest ecosystems, and is a premise to understand feedback mechanism of forest ecological system to atmospheric nitrogen deposition. This work was conducted under a Picea-Abies forest located in the southeast mountain environment comprehensive observation station of Chinese Academy of Sciences in 2012, to study the different forms of nitrogen deposition concentration and deposition calculated in different times in 2012. Annual wet deposition of inorganic nitrogen, NH₄⁺-N and NO₃^--N in through fall in Picea-Abies forest were 8.58, 6.22 and 2.36 kg N ha^-1 yr^-1, respectively. NH₄⁺-N was the dominant species in wet deposition, comprising 76.7% of total wet inorganic N deposition. The atmospheric nitrogen deposition has a significant seasonal change. High values of inorganic N concentration in through fall were found in summer and autumn, while lower values were found in spring and winter. NH₄⁺-N (y₁) and NO₃^--N (y₂) mineral nitrogen sediment in rainfall have significant positive correlation with the monthly average temperature (^oC) (R²=0.41 and R²=0.73, p<;0.001), and NO₃^--N (y₂) has significant positive correlation with the monthly average rainfall(x, unit: mm), y₂ = 0.0006x - 0.0023(R²=0.50, p<;0.01).