城市公共绿地中的大型古树提供了对人类福祉至关重要的多种价值观,包括生物多样性保护。然而,保护带有关键野生生物微生境的大型古树会干扰安全考虑。这个直观的概念,然而,有不充分和分散的证据支持.这里,我们使用510个样本地块的5974棵树的数据对这一过程进行了实证检验,在102个样本站点内组织为五胞胎,包括城市公园,墓地,休闲森林,和克拉科夫城市群的历史保护区,波兰。我们的分析表明,树木位于人们经常光顾的地区,或者步行道附近的人,长凳,或者游乐场,有较高的事故隐患,因此,必须进行密集的树木手术(修剪和伐木)以保持无害。大型古树,它们拥有最多样化的微生境,当它们崩溃时会带来更大的风险,尤其受到这些措施的影响。因此,我们发现,大树与事故危险加剧的同时发生会导致死亡和倾斜树木的重大损失,和有空洞的树木,受伤,皇冠枯木,真菌子实体,或附生植物,特别是在公园里,在较小程度上,在休闲森林中。显然,一些与树木有关的微生境,比如受伤,空腔,和微土,修剪后也会出现在危险的地方。我们的发现强调,出于安全考虑,大型古树的保护及其生态功能面临重大挑战。为了应对保护挑战,协调人类与生物多样性的共存,我们建议提高环境意识,重新评估树木文化和规划政策。这将涉及在城市周边和室内建立战略和口袋储备,允许较大的老树茁壮成长并发展重要的微栖息地,而不会损害公共安全。否则,我们有可能失去许多大型古树和/或它们对野生动物的优越价值,它将在几十年内再生,如果不是几个世纪。
Large old trees in urban public green spaces deliver a diversity of values essential for human well-being, including biodiversity conservation. Yet, the conservation of large old trees bearing key wildlife microhabitats interferes with safety considerations. This intuitive notion, however, is backed by an insufficient and scattered body of evidence. Here, we empirically examined this process using data on 5974 trees across 510 sample plots, organized as quintuplets within 102 sample sites, including urban parks, cemeteries, recreational forests, and historic reserves in the urban agglomeration of Kraków, Poland. Our analyses demonstrate that trees situated in areas frequently visited by people, or those near walking paths, benches, or playgrounds, have elevated accident hazards and, therefore, necessitate intensive tree surgeries (pruning and logging) to remain harmless. Large old trees, which bear the most diverse microhabitats and pose greater risks when they collapse, are especially affected by these measures. Accordingly, we found that the co-occurrence of large trees with elevated accident hazards results in significant losses of dead and sloped trees, and trees with cavities, injuries, crown deadwood, fungal fruiting bodies, or epiphytes, particularly in parks and, to a lesser extent, in recreational forests. Apparently, some tree-related microhabitats, such as injuries, cavities, and microsoils, also emerge in risky spots after pruning. Our findings underscore that the conservation of large old trees and their ecological functions faces significant challenges due to safety considerations. To address conservation challenges and harmonize human coexistence with biodiversity, we recommend enhancing environmental awareness and reevaluating arboricultural and planning policies. This would involve establishing strategic and pocket reserves on city peripheries and interiors, allowing larger older trees to thrive and develop important microhabitats without compromising public safety. Otherwise, we risk losing many large old trees and/or their superior value for wildlife, which will regenerate over decades, if not centuries.