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.

This paper studies the spatial distribution of rural residential land of the town of Yihe, Shilong and Runxi in Chongqing, and optimizes the spatial pattern based upon their urban-rural linkages. According to the intensity of urban-rural linkage derived from gravity model, the three towns are categorized into three types of rural areas, namely industrial expansion area at urban fringe, ecological conservation districts in the suburbs and agricultural districts in remote mountainous areas. The authors construct an evaluation system, consisting of general index and featured index. Every plaque of rural residential land is classified as developing, adjusting or removing according to the result of evaluation. Three modes of optimization are concluded from the case study. The proposed method of spatial optimization focuses on the diversity of rural development and deals with challenges for rural areas in contemporary China. It contributes to a balanced urban-rural development and provides scientific evidence for the New-Type urbanization plan.