Abstract: [Objective] To study the effect of slope aspect on the community characteristics of mountain steppe and to reveal the change rule of plant community in different growing seasons.[Method] The mountain steppe in the northern slope of Tianshan Mountain was chosen as the research object,and the method of field investigation and sampling were used,and grassland community characteristics in the different slopes (the east slope,the west slope and the slope crest) and different growth period (June,July,August and September)were measured.[Result] (1) The important value of Artemisiafrigida in the whole growing season showed the slope crest ＞ the east slope ＞ the west slope;The important value of Stipa capillata in the slope crest and the west slope was significantly higher than that of east slope by 67.1;-673.7; (P ＜0.05);and the important value of Carex turkestanica in June and July showed the east slope ≥ the west slope ＞ the slope crest.(2) The community coverage of east slope in June,August and September was significantly higher than that of the slope crest and the west slope 21.4;-36.1; (P ＜0.05),and the community density in August and September was significantly higher than that of thewest slope,but the community aboveground biomass in July was higher than that of the west slope.[Conclusion] The slope and the growing season play important role in the community characteristics of mountain steppe Tianshan Mountains.

摘要： [目的]研究坡向对山地草原群落特征的影响,揭示植物群落在生长季不同时期的变化规律.[方法]以新疆天山北坡山地草原为对象,采用野外取样的方法,测定不同坡向(东坡、坡顶和西坡)、不同生长季时期(6～9月)草地群落特征.[结果](1)冷蒿重要值在6～9月整体上表现出坡顶＞东坡＞西坡;针茅重要值在坡顶和西坡显著高于东坡的67.1; ～673.7; (P ＜0.05),短柱苔草的重要值在6～7月表现出东坡≥西坡＞坡顶.(2)在6月、8月、9月,东坡群落盖度比坡顶、西坡显著高了21.4; ～36.1;(P ＜0.05),8～9月东坡群落密度显著高于西坡,7月的群落地上生物量在东坡显著高于西坡.[结论]坡向和生长季时期对天山北坡山地草原的群落特征产生较大的影响.