Temporal dynamics of interaction strength in quantitative food webs: an integration of spatial food web theory with empirical patterns of host-parasitoid interactions

食物网是生态系统进程和生物多样性的关键驱动力。资源密度的变化可能是网络动态的关键决定因素。单一的消费者资源动态可以在最优觅食理论的框架中描述，但消费者对多物种情况下的资源密度和景观尺度的反应才开始正式描述。最近的食物网理论强调了转换行为和栖息地之间耦合的重要性。在这个项目中，我们将使用一个长期的数据集收集的寄生虫宿主食物网在北方森林地块，了解定量的食物网动态。在这个系统中，毛虫，云杉芽虫，是一个主要的草食性害虫，可能会驱动食物网结构。我们将检验经验模式是否与底层食物网理论相匹配。我们的核心目标是：（一）经验确定时间动态的相互作用强度的爆发物种在一个复杂的食物网的密度，（二）确定这种食物网水平的响应变化之间的低和高多样性景观，并确定哪些过程有助于这种响应，以及（三）开发一个模型，正式描述一个焦点物种是如何受到食物网结构的影响。最后，将该模型推广到不同的网络类型。我们的项目将说明时间的食物网动态是如何受到群落组成和觅食行为的影响。它将产生具体的假设，以指导未来的研究，并为改进害虫管理实践提供基础。

Food webs are crucial drivers of ecosystem processes and biodiversity. Variation in resource densities may be a key determinant of network dynamics. Single consumer-resource dynamics can be described in the framework of optimal foraging theory, but consumer responses to resource densities in multi-species cases and on landscape scales are only beginning to be formally described. Recent food web theory has highlighted the importance of switching behavior and coupling among habitats. In this project, we will use a longterm dataset of parasitoid-host food webs collected in boreal forest plots to understand quantitative food web dynamics. In this system, the caterpillar, spruce budworm, is a major herbivore pest that may drive food web structure. We will test if empirical patterns match landscape-level food web theory. Our core objectives are (i) to empirically determine temporal dynamics of interaction strengths in relation to density of an outbreak species in a complex food web, (ii) to determine how this food web-level response changes between low and high diversity landscapes and identify which processes contribute to this response, and (iii) to develop a model to formally describe how a focal species is affected by food web structure. Finally, this model will be generalized to different network types. Our project will illustrate how temporal food web dynamics are influenced by community composition and foraging behavior. It will generate specific hypotheses to guide future research and provide a basis for improving pest management practices.