Most trees and other woody plants growing within urban areas are deliberately cultivated native or non-native plants. Opportunities for spontaneous establishment and spread of woody species are scarce in an urban environment, especially if the establishment begins from seeds. We hypothesized that urban hedges might offer safe sites for the spontaneous establishment of woody plants, which reach the hedges through propagule dispersal. We recorded the species composition of urban hedges in Maribor (NE Slovenia) in a gradient from the city centre outwards and evaluated the species’ invasive potential and ecological requirements, along with hedge characteristics. Results show that hedges facilitated the survival and growth of 69 woody plants from 28 families. Among these, 62% were non-native and 10% were locally invasive. Most of recorded non-native woody plants were ornamentals. Moreover, for native species, we show that the stressful, warmer urban environment mostly facilitates the establishment of species in the genera and . Comparison of non-native and native plants showed the former are more drought and heat tolerant than the latter. We further show that with distance from the city centre, the number of bird-dispersed species increases, in contrast to the wind-dispersed species. Additionally, our results suggest evergreen hedges may be less permeable to wind-dispersed propagules than deciduous hedges. Next, we stress the importance of paved surfaces and urbanization, selecting for the thermophile, drought tolerant, wind-dispersed woody plants that find refuge in urban hedges. Our results suggest urban hedges can facilitate the establishment of a wide range of woody plant species.

中文翻译：

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城市树篱有利于木本植物的自然生长


城市地区生长的大多数树木和其他木本植物都是有意栽培的本地或非本地植物。在城市环境中，木本物种自发定居和传播的机会很少，特别是如果从种子开始定居的话。我们假设城市树篱可能为木本植物的自发生长提供安全场所，木本植物通过繁殖体传播到达树篱。我们以从市中心向外的梯度记录了马里博尔（斯洛文尼亚东北部）城市树篱的物种组成，并评估了该物种的入侵潜力和生态要求以及树篱特征。结果表明，树篱促进了28科69种木本植物的生存和生长。其中，62%是非本地的，10%是局部侵入的。大多数有记录的非本地木本植物都是观赏植物。此外，对于本地物种，我们表明，压力大、温暖的城市环境主要有利于物种在 和 中的建立。非本地植物和本地植物的比较表明，前者比后者更耐旱和耐热。我们进一步表明，随着距离市中心的距离增加，鸟类传播的物种数量增加，而风传播的物种则相反。此外，我们的结果表明，常绿树篱可能比落叶树篱更不易被风传播的繁殖体渗透。接下来，我们强调铺砌表面和城市化的重要性，选择在城市树篱中避难的耐热、耐旱、风散的木本植物。我们的研究结果表明，城市树篱可以促进多种木本植物物种的建立。