Rodewald Amanda D, Rohr Rudolf P, Fortuna Miguel A, Bascompte Jordi
School of Environment and Natural Resources, 2021 Coffey Road, The Ohio State University, Columbus, OH, 43210, USA.
Integrative Ecology Group, Estación Biológica de Doñana , CSIC C/ Americo Vespucio s/n, Sevilla, E-41092, Spain.
J Anim Ecol. 2014 Nov;83(6):1409-17. doi: 10.1111/1365-2656.12224. Epub 2014 May 19.
Ecological networks are known to influence ecosystem attributes, but we poorly understand how interspecific network structure affect population demography of multiple species, particularly for vertebrates. Establishing the link between network structure and demography is at the crux of being able to use networks to understand population dynamics and to inform conservation. We addressed the critical but unanswered question, does network structure explain demographic consequences of urbanization? We studied 141 ecological networks representing interactions between plants and nesting birds in forests across an urbanization gradient in Ohio, USA, from 2001 to 2011. Nest predators were identified by video-recording nests and surveyed from 2004 to 2011. As landscapes urbanized, bird-plant networks were more nested, less compartmentalized and dominated by strong interactions between a few species (i.e. low evenness). Evenness of interaction strengths promoted avian nest survival, and evenness explained demography better than urbanization, level of invasion, numbers of predators or other qualitative network metrics. Highly uneven networks had approximately half the nesting success as the most even networks. Thus, nest survival reflected how urbanization altered species interactions, particularly with respect to how nest placement affected search efficiency of predators. The demographic effects of urbanization were not direct, but were filtered through bird-plant networks. This study illustrates how network structure can influence demography at the community level and further, that knowledge of species interactions and a network approach may be requisite to understanding demographic responses to environmental change.
生态网络已知会影响生态系统属性，但我们对种间网络结构如何影响多个物种的种群统计学知之甚少，尤其是对于脊椎动物而言。建立网络结构与种群统计学之间的联系是能否利用网络来理解种群动态并为保护工作提供信息的关键所在。我们解决了这个关键但尚未得到解答的问题：网络结构能否解释城市化的人口统计学后果？我们研究了141个生态网络，这些网络代表了2001年至2011年美国俄亥俄州城市化梯度上森林中植物与筑巢鸟类之间的相互作用。通过对鸟巢进行视频记录来识别巢捕食者，并在2004年至2011年期间进行调查。随着景观城市化，鸟类 - 植物网络更加嵌套、分区性更低，并且由少数物种之间的强相互作用主导（即均匀度低）。相互作用强度的均匀度促进了鸟类巢穴的存活，并且均匀度比城市化、入侵程度、捕食者数量或其他定性网络指标更能解释种群统计学。高度不均匀的网络的筑巢成功率约为最均匀网络的一半。因此，巢穴存活反映了城市化如何改变物种相互作用，特别是巢穴位置如何影响捕食者的搜索效率。城市化的人口统计学影响不是直接的，而是通过鸟类 - 植物网络过滤的。这项研究说明了网络结构如何在群落水平上影响种群统计学，并且进一步表明，物种相互作用的知识和网络方法可能是理解对环境变化的种群统计学响应所必需的。
