Exposure to biodiverse environments such as forests can benefit human well-being, and evidence suggests exposure to high microbial diversity may improve mental and immune health. However, the factors that drive microbial community assembly are poorly understood, as is the relationship between exposure to these communities and human health. We characterized airborne bacterial communities in two disparate types of urban greenspace (forest and grass) in late-spring 2017 at sites previously sampled in late-summer 2015 in Eugene-Springfield, Oregon, using high-throughput metabarcode sequencing. While all sites shared a core aerobiome in late-spring consisting of plant- and soil-associated genera, forests had significantly higher diversity than grass sites (F = 12, P = 0.004). Vegetation type explained 14% of the difference between forest and grass aerobiomes, yet individual site location explained 41% of the variation. These results were similar to but amplified over those from late summer, suggesting that both aerobiome diversity and vegetation-driven effects are higher when deciduous foliage is fresher and more active, temperatures cooler, and humidity higher. Continued exploration and hypothesis-driven research will enable development of mechanistic theory describing key drivers of urban aerobiome assembly and its relationship to human health, which, in turn, will help urban designers and planners create evidence-based salutogenic cities for future generations.

接触森林等生物多样性环境可以造福人类，有证据表明接触高微生物多样性可以改善心理和免疫健康。然而，人们对推动微生物群落组装的因素知之甚少，接触这些群落与人类健康之间的关系也是如此。我们使用高通量元条形码测序，在 2015 年夏末俄勒冈州尤金-斯普林菲尔德之前采样的地点，于 2017 年春末对两种不同类型的城市绿地（森林和草地）中的空气传播细菌群落进行了表征。虽然所有地点在晚春都有一个由植物和土壤相关属组成的核心有氧生物群落，但森林的多样性明显高于草地（F  = 12，P = 0.004)。植被类型解释了森林和草地有氧生物群落差异的 14%，而单个站点位置解释了 41% 的变化。这些结果与夏末的结果相似但放大了，这表明当落叶叶更新鲜、更活跃、温度更低、湿度更高时，需氧生物群落多样性和植被驱动的影响都更高。持续的探索和假设驱动的研究将有助于发展描述城市有氧生物群落组装的关键驱动因素及其与人类健康关系的机械理论，这反过来又将帮助城市设计师和规划者为子孙后代创建以证据为基础的有益城市。