Population and food web responses to variation in rates and timing of pulsed, cross-ecosystem resource subsidies

许多生态群落从邻近的生态系统获得资源投入，有时是非常不稳定的，如落叶或陆生无脊椎动物落入溪流和森林湿地。研究表明，这些“跨生态系统资源补贴”，如凋落叶、无脊椎动物、鲑鱼、海蜇、花粉等，在很大程度上促进了接收生态系统的生产力。然而，关于这一主题的大多数实验涉及基于增加或排除补贴资源与环境参考或控制相比的二元比较。我们对投入率、时间、持续时间和资源质量等特征变化的定量效应如何影响接受者群体动态和生产力、社区进程和稳定性的理解有限。******在我们的研究中，我们使用落叶或陆生无脊椎动物输入流作为模型来测试对接收消费者的影响。然而，关于输入特征的数量梯度的后果问题仍需要从种群和群落动态的角度进行研究。一些河流捕食者直接使用补贴资源，我们已经用割喉鳟鱼作为模型系统来了解陆生无脊椎动物的投入如何影响它们的生长和繁殖。然而，对那些捕食者（包括无脊椎动物）的种群动态影响的研究很少，这些捕食者本身不直接使用补贴，即通过食物网调节影响。考虑到捕食者（无脊椎动物和脊椎动物）在食物网中的数量跨越了几个数量级，食物网的大小结构可能很重要，然而捕食者通常被归为一个单一的功能类别。因此，我们还将测试消费者尺寸依赖性反应的问题。此外，接受者消费者的生产力的提高很少被仔细地跟踪到他们食物网的其他部分，我们将解决这个问题。******我们使用了基于实地的实验操作来测试投入率和补贴质量的影响，并在考虑这些特征如何影响受援国人口和社区方面取得了一些进展。本文提出的工作将扩大我们对脉冲资源补贴如何影响受援国人口和社区的生产力和稳定性的理解和预测能力。此外，这项工作将有助于证明保护和管理与水生环境相邻的生态系统，例如在林业、农业和城市环境中，对于维持生产性和健康的淡水的重要性。*****

Many ecological communities receive resource inputs from adjacent ecosystems, sometimes very pulsed in time, such as leaf litter or terrestrial invertebrates falling into streams and wetlands in forests. Studies have shown that these “cross-ecosystem resource subsidies”, such as leaf litter, invertebrates, salmon, sea wrack, pollen and others, contribute in a large way to the productivity of the receiving ecosystems. However, most experiments on this topic involve binary comparisons based on augmentation or exclusion of a subsidy resource compared with an ambient reference or control. We have a limited understanding of how the quantitative effects of variation along characteristics of input rates, timing, duration and resource quality affects recipient population dynamics and productivity, community processes, and stability. ******In our research we have used leaf litter or terrestrial invertebrate inputs to streams as models to test the effects on receiving consumers. However, questions about consequences of quantitative gradients in input characteristics still need study in terms of population and community dynamics. Some stream predators use subsidy resources directly, and we have used cutthroat trout as a model system for understanding how inputs of terrestrial invertebrates affects their growth and reproduction. However, there are few studies of the consequences for population dynamics of those predators, including invertebrates, which do not directly use subsidies themselves, i.e. effects moderated through food webs. Food-web size structure is likely important given that predators (invertebrates and vertebrates) span several orders of magnitude in mass in food webs, and yet predators are often grouped as a single functional category. Thus, we will also test questions of size-dependent responses of consumers. Further, increases in productivity of recipient consumers have rarely been followed carefully into other parts of their food webs, which we will address.******We have used field-based experimental manipulations to test the effects of input rates and quality of subsidies, and have made some progress on considering how these characteristics affect recipient populations and communities. The work proposed here will expand our understanding and predictive capability of how pulsed resource subsidies affect the productivity and stability of recipient populations and communities. Moreover, this work will serve to demonstrate the importance of protecting and managing ecosystems adjacent to aquatic environments, e.g. in forestry, agricultural and urban settings, to sustain productive and healthy freshwaters.*****