Canopy composition drives variability in urban growing season length more than the heat island effect
Canopy composition drives variability in urban growing season length more than the heat island effect
复制标题
冠层组成对城市生长季节长度变化的影响大于热岛效应
DOI：
10.1016/j.scitotenv.2023.163818
复制
发表时间：
2023
影响因子：
9.8
通讯作者：
Elmore, Andrew J.
中科院分区：
文献类型：
--
作者：
Alonzo, Michael;Baker, Matthew E.;Caplan, Joshua S.;Williams, Avery;Elmore, Andrew J.
与周围环境相比，城市地区的高温升高使潮湿的温带城市成为未来气候对自然森林物候影响的有用预测。这一指标的效用基于这样一种预期，即城市地区的树木会改变其物候，以响应春季和秋季更温暖的场地条件。然而，生长季节的明显延长可能是由人为驱动的树种选择和管理景观中典型的植物功能类型（PFT；树木、灌木、草坪草）异质性决定的。如果不使用高度时空分辨率的遥感数据，树木分类学和当地站点特征（如不透水覆盖）在控制物候中的作用仍然是混乱的。为了了解城市树木季节提前开始（SOS）和季节晚结束（EOS）的驱动因素，我们每年（2018-2020年）使用bbb130张高分辨率卫星图像估计华盛顿特区约10,000棵物种标记的树木的单个树木物候。我们发现，与树木的种植位置特征相比，物种身份本身在SOS和EOS时间上的变异多出4倍。此外，与热量本身相比，pft的城市混合可能对SOS的明显进步（在1.8±1.3至3.5±1.3天之间）负有更大的责任。这项研究的结果提醒人们不要将城市较长的生长季节（在中等到粗分辨率遥感图像中观察到）与物种内物候可塑性联系起来，并证明了高分辨率卫星数据在生物多样性环境中跟踪树木物候的能力。
The elevated heat of urban areas compared to their surroundings makes humid temperate cities a useful preview of future climate effects on natural forest phenology. The utility of this proxy rests on the expectation that trees in urban areas alter their phenology in response to warmer site conditions in spring and fall. However, it is possible that apparent lengthening of the growing season is instead governed by human-driven tree species selection and plant functional type (PFT; trees, shrubs, turfgrass) heterogeneity typical of managed landscapes. Without the use of highly spatially and temporally resolved remote sensing data, the roles of tree taxonomy and local site characteristics (eg, impervious cover) in controlling phenology remain confounded. To understand the drivers of earlier start of season (SOS) and later end of season (EOS) among urban trees, we estimated individual tree phenology using> 130 high-resolution satellite images per year (2018-2020) for~ 10,000 species-labeled trees in Washington, DC. We found that species identity alone accounted for 4× more variability in the timing of SOS and EOS compared with a tree's planting location characteristics. Additionally, the urban mix of PFTs may be more responsible for apparent advances in SOS (by between 1.8±1.3 and 3.5±1.3 days) than heat per se. The results of this study caution against associating longer growing seasons in cities-observed in moderate to coarse resolution remote sensing imagery-to within-species phenological plasticity and demonstrate the power of high-resolution satellite data for tracking tree phenology in biodiverse environments.