Department of Biology, Center for Computational and Integrative Biology, Waterfront Technology Center, Rutgers University, 200 Federal Street, Camden, New Jersey, 08103, USA.
Department of Entomology and Plant Pathology, Keck Center for Behavioral Biology, North Carolina State University, Campus Box 7617, Raleigh, North Carolina, 27695, USA.
Ecol Appl. 2018 Jan;28(1):225-236. doi: 10.1002/eap.1643. Epub 2017 Dec 27.
The frequency and intensity of hurricanes are increasing globally, and anthropogenic modifications in cities have created systems that may be particularly vulnerable to their negative effects. Organisms living in cities are exposed to variable levels of chronic environmental stress. However, whether chronic stress ameliorates or exacerbates the negative effects of hurricanes remains an open question. Here, we consider two hypotheses about the simultaneous consequences of acute disturbances from hurricanes and chronic stress from urbanization for the structure of urban arthropod communities. The tipping point hypothesis posits that organisms living in high stress habitats are less resilient than those in low stress habitats because they are living near the limits of their environmental tolerances; while the disturbance tolerance hypothesis posits that high stress habitats host organisms pre-adapted for coping with disturbance, making them more resilient to the effects of storms. We used a before-after-control-impact design in the street medians and city parks of Manhattan (New York City, New York, USA) to compare arthropod communities before and after Super Storm Sandy in sites that were flooded and unflooded during the storm. Our evidence supported the disturbance tolerance hypothesis. Significant compositional differences between street medians and city parks before the storm disappeared after the storm; similarly, unflooded city parks had significantly different arthropod composition while flooded sites were indistinguishable. These differences were driven by reduced occurrences and abundances of arthropods in city parks. Finally, those arthropod groups that were most tolerant to urban stress were also the most tolerant to flooding. Our results suggest that the species that survive in high stress environments are likely to be the ones that thrive in response to acute disturbance. As storms become increasingly common and extreme, this juxtaposition in responses to storm-associated disturbance may lead to diversity loss in cities, potentially leading entire urban landscapes to mirror the reduced diversity of street medians.
飓风的频率和强度在全球范围内都在增加，城市中的人为改造创造了可能特别容易受到其负面影响的系统。生活在城市中的生物会暴露在不同程度的慢性环境压力下。然而，慢性压力是否会减轻或加剧飓风的负面影响仍然是一个悬而未决的问题。在这里，我们考虑了飓风带来的急性干扰和城市化带来的慢性压力对城市节肢动物群落结构同时产生的两种假设。临界点假说认为，生活在高压力生境中的生物比生活在低压力生境中的生物更没有弹性，因为它们生活在环境容忍度的极限附近；而干扰容忍假说则认为，高压力生境中栖息着适应应对干扰的生物，使它们对风暴的影响更具弹性。我们使用曼哈顿（美国纽约市）街道中央分隔带和城市公园中的前后对照影响设计，在风暴期间被洪水淹没和未被洪水淹没的地点，比较了超级风暴桑迪前后的节肢动物群落。我们的证据支持干扰容忍假说。风暴前街道中央分隔带和城市公园之间的显著组成差异在风暴后消失了；同样，未被洪水淹没的城市公园的节肢动物组成有显著差异，而被洪水淹没的地点则无法区分。这些差异是由城市公园中节肢动物的出现和丰度减少驱动的。最后，那些对城市压力最耐受的节肢动物群体也对洪水最耐受。我们的研究结果表明，在高压力环境中生存的物种很可能是对急性干扰做出反应的物种。随着风暴变得越来越普遍和极端，这种对风暴相关干扰的反应的并置可能会导致城市中的物种多样性丧失，这可能会导致整个城市景观模仿街道中央分隔带的减少多样性。
