Abstract:

Based on the warming and altered precipitation experiment platform at Haibei research station, this study investigated the responses of soil inorganic nitrogen to warming and altered precipitation in the growing season in alpine meadow. The results show that 1) warming significantly decreasesNH₄⁺-N by 47.5% (p=0.001) and NO₃-N by 85.4% (p=0.021); 2) effect of decreased precipitation on soil inorganic nitrogen is unequal to the effect of increased precipitation, increased precipitation significantly increasesNH₄⁺-N by 74.7% (p=0.046) and NO₃-N by 154% (p=0.017), while decreases precipitation tends to reduce NH₄⁺-N, but has no significant effect on NO₃-N; 3) NH₄⁺-N and NO₃-N are positively correlated with soil moisture, but has no correlations with soil temperature. Thus, soil moisture induced by warming and altered precipitation, is the main factor affecting inorganic nitrogen availability in the growing season. This study suggests that inorganic nitrogen availability will increase in tandem with increasing soil moisture, under the background of climate change in alpine meadow on the Qinghai-Tibetan Plateau.

Key words: Qinghai-Tibetan Plateau, global climate change, nitrogen cycling, soil moisture, NH₄⁺-N, NO₃-N

摘要：

基于海北站野外长期增温和降水改变控制平台, 研究高寒草甸生态系统生长季土壤无机氮对增温和降水改变的响应。结果表明, 增温使铵态氮降低 47.5% (p = 0.001), 硝态氮降低 46.1% (p = 0.021)。降水的改变对无机氮的影响存在不对称性, 增加降水使铵态氮增加 74.7% (p = 0.046), 硝态氮增加 154% (p = 0.017); 减少降水使铵态氮降低, 对硝态氮无显著影响。铵态氮、硝态氮随着土壤湿度的增加而增加, 与土壤温度无显著关系。这表明增温和降水改变主要通过改变土壤湿度而不是土壤温度影响生长季土壤无机氮。因此预测, 未来气候变化背景下, 土壤湿度的增加可能导致青藏高原高寒草甸土壤无机氮的可利用性增加。

关键词: 青藏高原, 全球气候变化, 氮循环, 土壤水分, 铵态氮, 硝态氮