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.

Because of the motor vehicle emissions high contribution on atmospheric air pollution in Beijing, the vehicle control policies need to be shift with the target of emission reduction. Based on the analysis of Beijing motor vehicle composition and pollution contribution, this paper presents the measure of phasing out high-emission vehicles. This measure directly controls the high-emission vehicles which have contributed most motor vehicle pollution, to maximize the environmental effects while controlling the same amount of vehicles. Comparing this measure with the measures of “controlling the new vehicles increasing” and “driving restriction”, the measure of phasing out high-emission vehicles has the highest cost-effectiveness ratio and it has significance effect in Beijing air pollution controlling and in achieving the twelfth “five years” NOx emission reduction targets. Considering the factors of the damage cost of the high-emission cars, the willingness to accept (WTA) of the owners of the phased cars, the incentive direction of the subsidies and the government budget, the authors propose that the subsidy standard would be a single one and the level of subsidy should be about 4000?6000 yuan per vehicle. Phasing out high-emission vehicles has multiple advantages: reflecting the cost-effectiveness of policy design, reflecting the policy direction of being responsible for the environment and the incentive effects of economical instruments.