南京5种木本植物早春花期物候对城市热岛效应的响应研究

The flowering phenology response of five early spring woody plants to the urban heat island effect in Nanjing

【目的】植物物候作为城市生态系统的指示器,能够直观反映城市化进程下生态系统的变化。本研究结合地表温度数据,探究南京市5种常见观花木本植物的花期物候对热岛效应的响应规律,为明晰我国华东地区植被物候对热岛效应的响应机制提供依据。【方法】基于Landsat 8遥感数据反演南京市地表温度,采用热岛比例指数(URI)表征热岛强度,结合花期物候观测数据,定量研究城市热岛效应对植物花期物候的影响。【结果】南京市城市热岛效应明显,热岛强度从大到小排序为:中心城区>近郊区>远郊区。5种植物对热岛效应的敏感度存在明显差异,白玉兰(Yulania denudata)对城市热岛效应的响应最敏感,花期可提前4~11 d,花期持续时间最多缩短50%;巨紫荆(Cercis gigantea)、垂丝海棠(Malus halliana)、东京樱花(Prunus yedoensis)受影响程度相近;红花檵木(Loropetalum chinense var.rubrum)受影响程度最小,花期提前2~4 d,花期持续时间缩短约19%。【结论】热岛效应对植物花期的起止时间和持续时间皆存在显著影响,随着热岛效应的增强,植物始花期、盛花期和末花期均出现提前和缩短趋势,在未来的研究中,可探讨其他植被类型对城市热岛的响应,以进一步揭示植物物候对城市气候变化的响应规律。

【Objective】As an indicator of urban ecosystems,plant phenology can visually reflect the changes of ecosystem under the process of urbanization.In this study,we investigated the response pattern of flowering phenology of five common flowering woody species to the heat island effect in Nanjing,and provided data supplement for the response mechanism of vegetation phenology to the heat island effect in East China.【Method】Based on Landsat 8 remote sensing data to invert the surface temperature of Nanjing,the urban heat island radio index(URI)was used to characterize the heat island intensity,and the combined with the flowering phenology observation data to quantitatively study the effect of urban heat island effect on the flowering phenology of plants.【Result】Nanjing showed a significant urban heat island effect.Heat island intensity ranking:central city>suburban area>remote suburban area.The sensitivity of the same plant to the heat island effect differed at different points.Among the five plants,Yulania denudata was the most affected by the heat island effect,with the flowering period advanced by four to 11 days and the flowering period duration shortened by up to 50%;Cercis gigantea,Malus halliana and Prunus yedoensis were affected to a similar extent and were at a medium level;Loropetalum chinense var.rubrum was the least affected,with the flowering period advanced by about two to four days and the flowering period duration shortened by about 19%.【Conclusion】The heat island effect has a significant effect on the onset and duration of flowering periods of plants,and as the heat island effect increases,the onset,bloom and last flowering periods of plants tend to be earlier and shorter.