Extreme heatwaves and drought have been shown to significantly affect urban tree survival, with potentially substantial economic costs for urban managers and local governments. During the 2019–2020 austral summer, the western Sydney Local Government Area (LGA) of Penrith experienced unprecedented high temperatures with less than 60 % of average rainfall compared with the proceeding five summers. This culminated in the highest temperature ever recorded in greater Sydney, of 48.9 °C. It is increasingly important that trees for urban applications are selected to be able to withstand such conditions. In early 2020, we conducted a visual assessment of canopy damage on street trees found in the Penrith LGA following the 2019–2020 summer heatwaves. We assessed the health of over 5500 trees and classified them as undamaged, lightly damaged, heavily damaged or defoliated. We found that more than 10 % of all the trees assessed displayed some level of canopy damage, with exotic deciduous species showing the greatest proportion of canopy damage. A logistic regression revealed that for exotic deciduous species, the probability of having sustained no canopy damage was 79 % lower than that for native evergreen species. Using these data, the economic costs to replace damaged trees was calculated using two scenarios that incorporated costs of tree planting and maintenance: low cost (replacing all heavily damaged and defoliated trees with juvenile trees) and high cost (replacing all heavily damaged and defoliated trees with advanced trees), with costs ranging from $500,000 to $800,000 (AUD). We also calculated the cost of replacing all individuals of the most damaged species with more climate-resilient species in order to secure the urban forest and found that the cost would be over AUD$1,000,000. This research highlights the importance of careful planning to ensure urban forest resilience and economic sustainability in the face of climate change.

极端热浪和干旱已被证明会显着影响城市树木的生存，给城市管理者和地方政府带来潜在的巨大经济成本。在 2019 年至 2020 年的南方夏季期间，彭里斯的悉尼西部地方政府区 (LGA) 经历了前所未有的高温，与随后的五个夏季相比，平均降雨量不到 60%。这最终导致大悉尼地区有史以来的最高温度达到 48.9 °C。选择用于城市应用的树木能够承受这样的条件变得越来越重要。2020 年初，我们对 2019-2020 年夏季热浪之后在彭里斯 LGA 中发现的行道树的树冠损坏进行了目视评估。我们评估了 5500 多棵树的健康状况，并将它们归类为未损坏、轻度损坏、严重损坏或落叶。我们发现，在所有评估的树木中，超过 10% 的树木显示出一定程度的树冠损坏，其中外来落叶树种的树冠损坏比例最大。逻辑回归显示，对于外来落叶树种，没有遭受冠层损害的概率比本地常绿树种低 79%。使用这些数据，更换受损树木的经济成本使用两种方案计算，其中包括植树和维护成本：低成本（用幼树更换所有严重受损和落叶的树木）和高成本（更换所有严重受损和落叶的树木）高级树木），成本从 500,000 美元到 800,000 美元（澳元）不等。我们还计算了为保护城市森林而用更具气候适应性的物种替换所有受损最严重物种的成本，发现成本将超过 1,000,000 澳元。这项研究强调了仔细规划以确保面对气候变化时城市森林恢复力和经济可持续性的重要性。