One common measure to mitigate the impacts of rising temperatures within cities is increasing the amount of vegetation, especially urban trees and their canopies. To maximize the associated benefits of urban trees in a given city or neighborhood, it is important that the canopy of newly planted trees matches or exceeds the canopy of the trees that are lost. However, cities often use cross-sectional data to make decisions about the number of trees that should be planted without considering an individual tree’s growth and life span. In this study, individual tree growth and longevity data were used to portray the current and future conditions of street trees in six neighborhoods near Downtown Los Angeles and to identify locations in those neighborhoods that are in urgent need of interventions for tree planting. The results of this study indicate that, under the typical tree mortality scenario, near half of the current tree canopy will disappear by 2050, and on average, approximately one percent of the existing street trees will be lost due to aging each year. The approach used in this study shows how cities can monitor the age and mortality rate of the urban tree canopy over time. This approach informs tree planting campaigns that will preserve the long-term vitality and size of urban tree canopies and contribute to the resiliency of cities in a warmer future climate.

中文翻译：

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监测城市行道树冠生命周期的新方法


减轻城市气温上升影响的一种常见措施是增加植被的数量，尤其是城市树木及其树冠。为了最大限度地发挥给定城市或社区中城市树木的相关优势，新种植的树木的树冠必须与损失的树木的树冠相匹配或超过。然而，城市经常使用横截面数据来决定应该种植的树木数量，而不考虑单棵树的生长和寿命。在这项研究中，单棵树的生长和寿命数据被用来描述洛杉矶市中心附近六个社区的行道树的当前和未来状况，并确定那些社区中急需植树干预的位置。这项研究的结果表明，在典型的树木死亡情景下，到 2050 年，当前树冠的近一半将消失，平均而言，每年约有 1% 的现有行道树将因老化而消失。本研究中使用的方法展示了城市如何监测城市树冠的年龄和死亡率随时间的变化。这种方法为植树活动提供了信息，这些活动将保持城市树冠的长期活力和大小，并有助于城市在未来气候变暖的情况下保持弹性。