Srivastava Diane S, Harris Noam, Páez Nadia, Rogy Pierre, Westwood Natalie Elena, Sandoval-Acuña Pablo, Seetharaman Keerthikrutha
Biodiversity Research Centre and Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
Department of Biology, University of Regina, Regina, Saskatchewan, Canada.
Ecology. 2024 Jan;105(1):e4204. doi: 10.1002/ecy.4204. Epub 2023 Nov 23.
Cities can have profound impacts on ecosystems, yet our understanding of these impacts is currently limited. First, the effects of the socioeconomic dimensions of human society are often overlooked. Second, correlative analyses are common, limiting our causal understanding of mechanisms. Third, most research has focused on terrestrial systems, ignoring aquatic systems that also provide important ecosystem services. Here we compare the effects of human population density and low-income prevalence on the macroinvertebrate communities and ecosystem processes within water-filled artificial tree holes. We hypothesized that these human demographic variables would affect tree holes in different ways via changes in temperature, water nutrients, and the local tree hole environment. We recruited community scientists across Greater Vancouver (Canada) to provide host trees and tend 50 tree holes over 14 weeks of colonization. We quantified tree hole ecosystems in terms of aquatic invertebrates, litter decomposition, and chlorophyll a (chl a). We compiled potential explanatory variables from field measurements, satellite images, or census databases. Using structural equation models, we showed that invertebrate abundance was affected by low-income prevalence but not human population density. This was driven by cosmopolitan species of Ceratopogonidae (Diptera) with known associations to anthropogenic containers. Invertebrate diversity and abundance were also affected by environmental factors, such as temperature, elevation, water nutrients, litter quantity, and exposure. By contrast, invertebrate biomass, chl a, and litter decomposition were not affected by any measured variables. In summary, this study shows that some urban ecosystems can be largely unaffected by human population density. Our study also demonstrates the potential of using artificial tree holes as a standardized, replicated habitat for studying urbanization. Finally, by combining community science and urban ecology, we were able to involve our local community in this pandemic research pivot.
城市会对生态系统产生深远影响，但目前我们对这些影响的了解有限。首先，人类社会社会经济层面的影响常常被忽视。其次，相关性分析很常见，这限制了我们对机制的因果理解。第三，大多数研究都集中在陆地系统，而忽略了同样提供重要生态系统服务的水生系统。在这里，我们比较了人口密度和低收入患病率对充满水的人工树洞中的大型无脊椎动物群落和生态系统过程的影响。我们假设这些人类人口统计学变量会通过温度、水体养分和当地树洞环境的变化以不同方式影响树洞。我们招募了加拿大温哥华地区的社区科学家，让他们提供寄主树，并在14周的定殖期内照料50个树洞。我们从水生无脊椎动物、凋落物分解和叶绿素a（chl a）方面对树洞生态系统进行了量化。我们从实地测量、卫星图像或人口普查数据库中收集了潜在的解释变量。使用结构方程模型，我们发现无脊椎动物的丰度受低收入患病率影响，但不受人口密度影响。这是由已知与人为容器有关联的双翅目蠓科的世界性物种驱动的。无脊椎动物的多样性和丰度也受到环境因素的影响，如温度、海拔、水体养分、凋落物数量和暴露程度。相比之下，无脊椎动物生物量、chl a和凋落物分解不受任何测量变量的影响。总之，这项研究表明，一些城市生态系统在很大程度上可能不受人口密度的影响。我们的研究还展示了利用人工树洞作为标准化、可重复的栖息地来研究城市化的潜力。最后，通过将社区科学与城市生态学相结合，我们能够让当地社区参与到这场疫情研究转向中来。
