有机无机肥配施提高麦-稻轮作系统中水稻氮肥利用率的机制

采用盆栽试验，研究了有机无机肥配施对麦-稻轮作系统中水稻氮素累积动态和土壤氮素供应动态的影响，并从微生物学角度探讨了有机无机肥协同提高水稻氮肥利用率的机制.结果表明：有机无机肥配施处理的土壤微生物生物量碳、氮和矿质态氮在水稻分蘖期前低于化肥处理，而在抽穗期至灌浆期显著高于其他处理.土壤氮素供应动态与水稻吸收利用氮素规律吻合程度最高，促进了水稻产量、生物量和氮素累积量的增加，显著提高了水稻的氮肥利用率.其主要机制是有机无机肥配施促进了土壤微生物繁殖，使其在水稻生育前期固持了较多的矿质氮，在水稻生育中、后期这些氮素逐渐被释放以供水稻吸收利用，较好地满足了水稻各阶段生长发育对氮素养分的需求.

Avoidance distances of four ungulates from roads in Kekexili and related protection suggestions

The avoidance distance from road is the trade-off between resources availability and predation risk of wildlife.To provide protection strategies for wild ungulates,an investigation was conducted in June and August 2010 to study the avoidance distances of the ungulates Tibetan gazelle(Procapra picticaudata),Tibetan antelope(Pantholops hodgsonii),Kiang(Equus kiang),and wild yak(Bos grunniens) from Qinghai-Tibet Highway in Kekexili,and the effects of traffic flow on the avoidance distances of Tibetan gazelle and Tibetan antelope.The avoidance distances of the four ungulates decreased in the order of wild yak(999.00 m±304.17 m),Kiang(568.39 m±83.23 m),Tibetan antelope(286.31 m±26.73 m),and Tibetan gazelle(176.97 m±14.47 m),and there existed significant differences among the four avoidance distances.Traffic flow had no effects on the avoidance distances of Tibetan gazelle and Tibetan antelope,which might be related to the low sensitivities of the two ungulates to the regular disturbance.It was suggested that the establishment of wildlife channels,limited human activities,and adjustment of the distances between roads would be the efficient ways to decrease the negative effects of road on wildlife.