沈阳城市森林主要树种物候对气候变暖的响应

采用统计和线性回归方法，探讨了近40年来沈阳城市森林主要树种物候对气候变暖的响应.结果表明，沈阳城市森林树木休眠期长短与冬季气温密切相关，适宜的寒冷条件有利于解除树木休眠期；树木萌动期早晚与冬季和早春气温高低呈显著的负相关关系，冬春季气温越高，芽萌动越提前.树木爆芽后15 d左右开始展叶，展叶早晚主要受展叶前的春季气温高低的影响，但与冬季气温没有相关关系.始花前2～8旬，特别是2～4旬气温对始花期影响最显著，春季气温升高始花期提前. 树木芽萌动期、展叶始期与寒冷指数（CI）呈显著正相关关系，而开花始期与CI没有相关关系.沈阳城市森林树木对气候变暖的响应，主要表现在年均温升高1 ℃，芽萌动期提前9 d，展叶始期提前10 d，开花始期提前5 d.

Responses of Shenyang urban tree phenology to climate warming

By using statistic and linear regression methods, this paper studied the last 40 years responses of Shenyang urban tree phenology to climate warming. The results showed that there was a significant correlation between the duration of tree dormancy and the mean air temperature in winter. Appropriate cold condition was beneficial to bud break, and a significant negative correlation was observed between the outset of sprouting and the mean air temperature in winter and early spring. Leaf expansion started 15 days after sprouting, which was mainly affected by the mean air temperature in spring but had no correlation with the temperature in winter. The air temperature within 20-80 days and especially 20-40 days before flowering had a significant effect on the outset of flowering, i. e. , an increasing temperature in spring could advance the outset of flowering. Both sprouting and leaf expansion were negatively correlated with cold index (CI) , but no significant correlation was observed between the outset of flowering and CI. An increase of mean annual air temperature by 1 degree C would advance the outset of sprouting by 9 days, leaf expansion by 10 days, and outset of flowering by 5 days.