Since 2007, more people in the world live in urban than in rural areas. The development of urban areas has encroached into natural forest ecosystems, consequently increasing the ecological importance of parks and fragmented forest remnants. However, a major concern is that urban activities have rendered urban forests susceptible to non-native species incursions, making them central entry sites where non-native plant species can establish and spread. We have little understanding of what urban factors contribute to this process. Here we use data collected by citizen scientists to determine the differential impacts of spatial and urban factors on non-native plant introductions in urban forests. Using a model city, we mapped 18 urban forests within city limits, and identified all the native and non-native plants present at those sites. We then determined the relative contribution of spatial and socioeconomic variables on the richness and composition of native and non-native plant communities. We found that socioeconomic factors rather than spatial factors (e.g., urban forest area) were important modulators of overall or non-native species richness. Non-native species richness in urban forest fragments was primarily affected by residential layout, recent construction events, and nearby roads. This demonstrates that the proliferation of non-native species is inherent to urban activities and we propose that future studies replicate our approach in different cities to broaden our understanding of the spatial and social factors that modulate invasive species movement starting in urban areas.

中文翻译：

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使用公民科学评估人类和空间压力对城市森林中非本地植物建立的相对重要性

自2007年以来，世界上城市人口多于农村人口。城市地区的发展已侵入天然森林生态系统，因此增加了公园和零散的森林残余物的生态重要性。但是，一个主要问题是城市活动使城市森林容易受到非本地物种入侵的影响，使其成为非本地植物物种可以建立和传播的中心入境地点。我们几乎不了解哪些城市因素导致了这一过程。在这里，我们使用公民科学家收集的数据来确定空间和城市因素对城市森林中非本地植物引进的不同影响。使用模型城市，我们在城市范围内绘制了18种城市森林的地图，并确定了这些站点上存在的所有本地和非本地植物。然后，我们确定了空间和社会经济变量对本地和非本地植物群落的丰富度和组成的相对贡献。我们发现，社会经济因素而不是空间因素（例如，城市森林面积）是整体或非本地物种丰富度的重要调节因素。城市森林碎片中的非本地物种丰富度主要受到住宅布局，近期建筑事件和附近道路的影响。这表明非本地物种的扩散是城市活动固有的，我们建议未来的研究在不同城市中复制我们的方法，以加深我们对影响从城市地区开始入侵物种移动的空间和社会因素的理解。