上海不同落叶树种展叶物候的影响因素

Driving factors of leaf-unfolding phenology in deciduous trees in Shanghai

为探究城市环境差异对树木展叶物候的影响,以上海城市森林中的纯林为研究对象,利用遥感数据提取9种树木的展叶开始时间,并分析其与温度、降水和夜间灯光之间的关系.结果显示如下.①展叶时间在物种之间存在差异,平均展叶时间从第95天至第104天;相比之下,展叶时间的种内差异更大,最早为第69天,最晚为第138天.②不同物种展叶物候对环境因子的响应不同:乌桕对降水变化最敏感,复羽叶栾对降水变化和城市化水平敏感,池杉对降水和温度变化敏感,其余6种树木对环境变化不敏感.③对于敏感物种,生长季前的平均降水量从48 mm增加64 mm,展叶开始时间提前45 d;平均温度每增加1℃,展叶开始时间延迟3 d.因而,城市森林建设可以根据树种物候的环境响应特点来进行合理配置,使其能更好地适应环境,发挥相应的生态作用.

To investigate the influence of urban environmental differences on the leaf-unfolding phenology of trees,we extracted the leaf unfolding information of nine tree species using remote sensing data and analyzed their relationships with temperature,precipitation,and nighttime light in a pure forest in Shanghai.The results showed that:①there were significant differences in the average onset of the leaf-unfolding phenology among species,from 95th to 104th day of the year;contrastingly,intra-species variation in leaf-unfolding date was greater,ranging from 69th to 138th day of the year.②Different species exhibited different leaf phenology in response to environmental factors.Triadica sebifera was the most sensitive to precipitation changes,Taxodium distichum var.imbricatum was sensitive to precipitation changes and urbanization,and Koelreuteria bipinnata was sensitive to precipitation and climate changes.Other species were not sensitive to any environmental changes.③For species sensitive to environmental changes,the leaf-unfolding date was 45 days earlier when the average precipitation increase from 48 mm to 64 mm,and delayed by three days for every 1°C increase in average temperature before the growing season.The study showed that urban forest construction can be reasonably configured according to the response characteristics of a species to the environment,so that plants can better adapt to the environment and fulfill their roles in the ecosystem.