Abstract In addition to social and economic benefits, urban trees provide habitats for many different species and contribute significantly to urban biodiversity. To prevent harm to humans or infrastructure, tree risk assessment is conducted regularly in urban areas. Resultant pruning activities are often criticized as leading to unnecessary injuries and artificial tree shapes. In this study we compared different tree maintenance levels and the occurrence of biodiversity related structures, so-called tree microhabitats, to provide another perspective on the consequences of pruning urban trees. For a sample of urban street and park trees in Montreal, Quebec, Canada, we found that the positive relationship between tree size (diameter at breast height) and microhabitat abundance and diversity was less steep than in a nearby forest with comparable species composition. Intensive tree maintenance in urban trees led to levels of certain microhabitats such as cavities and injuries that were comparable to natural, unmanaged forests. Light maintenance of urban trees encouraged more crown deadwood than typical and intensive maintenance levels. Tree species as well as cardinal direction of the nearest building played a minor role in the occurrence and development of microhabitats. Our results underline the importance of conserving and maintaining large living trees, especially in urban areas to provide tree microhabitats. These results also demonstrate the important role of intensive tree maintenance in stimulating tree microhabitat development in urban areas. However, new ways have to be found to reconcile the need for microhabitats and the maintenance of structurally healthy urban trees.

中文翻译：

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树木伤口的好处：受密集树木维护影响的城市树木的微生境发展

摘要 除了社会和经济效益外，城市树木还为许多不同物种提供栖息地，并对城市生物多样性做出重大贡献。为防止对人类或基础设施造成伤害，城市地区定期进行树木风险评估。由此产生的修剪活动经常被批评为导致不必要的伤害和人造树的形状。在这项研究中，我们比较了不同的树木维护水平和生物多样性相关结构（即所谓的树木微生境）的发生，以提供关于修剪城市树木后果的另一个视角。对于加拿大魁北克省蒙特利尔的城市街道和公园树木的样本，我们发现，树木大小（胸高直径）与微生境丰度和多样性之间的正相关关系不如附近具有可比物种组成的森林那么陡峭。城市树木中的密集树木维护导致某些微生境的水平，例如与天然、未管理的森林相媲美的空洞和伤害。城市树木的轻度维护鼓励比典型和密集维护水平更多的树冠枯死。树种以及最近建筑物的基本方向在微生境的发生和发展中起次要作用。我们的结果强调了保护和维护大型活树的重要性，尤其是在城市地区，以提供树木微生境。这些结果还证明了强化树木维护在刺激城市地区树木微生境发展方面的重要作用。然而，必须找到新的方法来协调对微生境的需求和维护结构健康的城市树木。