中文摘要：

植物物候作为气候变化敏感的生物圈指示计,已经成为全球变化研究的热点。利用1985～2002年地面物候观测数据,构建了内蒙古克氏针茅（Stipa krylovii）草原植物物候的时间序列谱,并分析了植物物候的时间变异与气候因子之间的相关关系。结果表明：1）从1985~2002年内蒙古克氏针茅草原的气候朝着暖干趋势发展,主要表现在春、夏气温的显著性增加与秋季（9月）降水的显著性减少;2）主要植物物候的变化整体呈返青期推后其它物候期提前趋势;3）植物生长盛期（7、8月）对气候变化最敏感;4）光照和温度是影响内蒙古克氏针茅草原植物物候格局的主要因素,年内最寒冷的1月月均温和2、3月的光照对春季返青期具有负效应,而其它物候期与7、8月的光照则呈显著的负相关关系,6、7月的降水对发育盛期的花序形成、抽穗与开花具有显著的负效应,8、9月的降水量能显著推后枯黄期的结束,从而有利于生长季的延长。

英文摘要：

Aims Recent studies, including field measurements, satellite-derived vegetation indices and simulations from a dynamic vegetation model, have demonstrated that global warming is influenc- ing plant growth and phenology. Changes in plant phenology have considerable consequences for eco- system function, but information on responses of plant phenology to climate change is lacking, especially in a community setting. Therefore, to accurately predict the future responses of plants to climate variation, a through understanding of plant phenological cycles and their relationships to light, tem- perature and precipitation is required. Methods We compiled a phenological calendar with 31 phenophases of budding, inflorescence, tas- selling, flowering, fruiting and senescence for Leymus chinensis, Stipa krylovii, Cleistogenes squarrosa, Allium anisopodium, Artemisia frigida, Heteropappus altaicus and Artemisia scoparia for semi-arid Stipa krylovii steppe in Inner Mongolia from 1985 to 2002. Relationships among phenophases, variability, and climatic driving were examined using correlation analysis. Important findings The climate of Stipa krylovii steppe exhibited a trend for wanning and drying, with significantly increased air temperature in spring and summer and markedly decreased precipitation in autumn. Linear regression analysis indicated that spring phenophases occurred later and summer and autumn phenophases moved earlier. Phenophases in July and August with higher temperature were the most sensitive to climate change. Plant phenology was primarily controlled by light and air temperature. Phenophases of budding were highly correlated with canopy light interception in February and March and with air temperature of the coldest month, January. Other phenophases, from inflorescence, tas- selling, flowering, fruiting to senescence, were negatively correlated with canopy light interception in July and August, and precipitation in June and July was negatively related to inflorescence, tasselling and flowering. The timing of se