植物物候对重庆主城区热岛效应的响应

为探究植物物候对山地城市内部热岛效应的响应特征,于2016年1月—2017年1月对重庆市主城区80种木本植物进行地面物候观测,同时利用Landsat 8热红外数据反演研究区地表温度,结合同时期地面实测气温,对研究区热岛强度等级进行划分,进而比较城市内部不同热岛强度等级下植物物候变化特征。结果表明,热岛过渡区与热岛区植物展叶期较凉岛区分别提前了5.1 d和8.1 d,初花期分别提前了4.0 d和20.8 d,终花期分别提前了4.8 d和11.6 d,而落叶期分别推迟了8.5 d和18.9 d,即城市内部热岛増温使植物春季物候提前,秋季物候推迟,生长季延长,且物候变化幅度随热岛强度等级增大而增大。不同功能型植物物候对热岛増温的响应存在差异,灌木、常绿植物和引种植物物候比乔木、落叶植物和本土植物更加敏感。本研究在一定程度上填补了我国西南山区物候研究的空缺,可为预测城市植物物候对未来山地城市小气候变化乃至全球气候变暖趋势的响应提供早期预警。

The phenological responses of plants to the heat island effect in the main urban area of Chongqing

In this study, we aimed to reveal the impact of the urban heat island effect on plant phenology in a mountain city, To this end, ground observations of the phenology of 80 woody plants were conducted from January 2016 to January 2017 in the main urban area of Chongqing, and Landsat 8 thermal infrared data as well as concurrent temperature data were used for classification of heat island intensity. The result showed that, compared with a cool island, the urban heat island has led to an advance in the transition zone and heat island zone for spring phenology (5.1 and 8.1 days for the timing of leaf expansion, 4.0 and 20.8 days for the timing of blossoming, and 4.8 and 11.6 days for the timing of flower fall, respectively), and a delay for autumn phenology (8.5 and 18.9 days for the timing of leaf fall, respectively). Furthermore, the growth season has been extended. Differences existed among functional types in response to urban heat island effect; the sensitivity of shrubs, evergreens and exotic plants to urban warming were found to be higher than that of trees, and deciduous and native species. Our research, to some extent, fills the gap in the research on phenology in the southwest area of China and might provide an early warning for predicting the phenological responses of urban plants to future urban microclimate changes in mountain cities and even to global warming trends.