Nowlin Weston H, Vanni Michael J, Yang Louie H
Department of Biology, Texas State University, Aquatic Station, San Marcos, Texas 78666, USA.
Ecology. 2008 Mar;89(3):647-59. doi: 10.1890/07-0303.1.
Resource pulses affect productivity and dynamics in a diversity of ecosystems, including islands, forests, streams, and lakes. Terrestrial and aquatic systems differ in food web structure and biogeochemistry; thus they may also differ in their responses to resource pulses. However, there has been a limited attempt to compare responses across ecosystem types. Here, we identify similarities and differences in the causes and consequences of resource pulses in terrestrial and aquatic systems. We propose that different patterns of food web and ecosystem structure in terrestrial and aquatic systems lead to different responses to resource pulses. Two predictions emerge from a comparison of resource pulses in the literature: (1) the bottom-up effects of resource pulses should transmit through aquatic food webs faster because of differences in the growth rates, life history, and stoichiometry of organisms in aquatic vs. terrestrial systems, and (2) the impacts of resource pulses should also persist longer in terrestrial systems because of longer generation times, the long-lived nature of many terrestrial resource pulses, and reduced top-down effects of consumers in terrestrial systems compared to aquatic systems. To examine these predictions, we use a case study of a resource pulse that affects both terrestrial and aquatic systems: the synchronous emergence of periodical cicadas (Magicicada spp.) in eastern North American forests. In general, studies that have examined the effects of periodical cicadas on terrestrial and aquatic systems support the prediction that resource pulses transmit more rapidly in aquatic systems; however, support for the prediction that resource pulse effects persist longer in terrestrial systems is equivocal. We conclude that there is a need to elucidate the indirect effects and long-term implications of resource pulses in both terrestrial and aquatic ecosystems.
资源脉冲会影响包括岛屿、森林、溪流和湖泊在内的多种生态系统的生产力和动态变化。陆地和水生系统在食物网结构和生物地球化学方面存在差异；因此，它们对资源脉冲的响应可能也有所不同。然而，跨生态系统类型比较响应的尝试有限。在这里，我们确定陆地和水生系统中资源脉冲的成因及后果的异同。我们提出，陆地和水生系统中不同的食物网和生态系统结构模式导致对资源脉冲的不同响应。通过比较文献中的资源脉冲得出两个预测：（1）由于水生和陆地系统中生物的生长速率、生活史和化学计量存在差异，资源脉冲的自下而上效应在水生食物网中的传递速度应该更快；（2）由于世代时间更长、许多陆地资源脉冲具有长期存在的性质以及与水生系统相比陆地系统中消费者的自上而下效应减弱，资源脉冲的影响在陆地系统中也应该持续更长时间。为了检验这些预测，我们以一个影响陆地和水生系统的资源脉冲为例进行研究：北美东部森林中周期性蝉（魔蝉属）的同步羽化。总体而言，研究周期性蝉对陆地和水生系统影响的研究支持了资源脉冲在水生系统中传递更快的预测；然而，对于资源脉冲影响在陆地系统中持续更长时间这一预测的支持并不明确。我们得出结论，有必要阐明资源脉冲在陆地和水生生态系统中的间接影响和长期影响。
