The impacts of species introductions on plant-pollinator network interactions

植物是大多数陆地生态系统的基础。大约85%的植物物种需要动物传粉者来繁殖和生存。然而，由于大量主要由人类驱动的压力因素，传粉媒介被认为在全球范围内处于危险之中，可能对全球生态系统造成破坏性后果。在过去的几十年里，生态学家已经产生了大量的文献，将人为压力源与传粉媒介群落的丰度和多样性下降联系起来，但很少有人关注这种变化对植物-传粉媒介相互作用的影响。尽管如此，在一个群落中添加开花植物是一种越来越普遍的恢复方法，其目标是增强各种生态系统中植物与传粉者的相互作用。令人惊讶的是，最近的一项荟萃分析发现，这种种植方案（即树篱或花带）对附近植物的授粉没有一致的影响，这表明我们对植物或传粉者群落的变化如何影响它们的相互作用网络和影响授粉服务的理解存在许多空白。拟议的研究计划将利用最近在温哥华市发起的公园修复计划。我的长期目标是提高我们对当地植物群落的增强如何影响植物-传粉者相互作用的生长，稳定性和持久性的理解，这对如何管理生态系统具有政策意义。我假设结果的变化部分是由于缺乏对增强和现有社区之间特征匹配的关注。理想情况下，加强植物群落将增加当地传粉者物种的定植和繁殖，从而增加其相互作用网络的多样性和强度。为了测试植物-传粉者相互作用的长期动态，我们将收集处理（野花增强）公园的植物性状和传粉网络的详细信息，并将其与对照公园在多个季节进行比较。利用基于网络的模块化（网络由相互作用的子单元组成的程度）和嵌套性（内部网络是更大网络的子集的程度）的稳定性信息，我们将研究随着不同植物传粉者特征重叠的增强，网络如何随着时间的推移而变化。为了验证花卉增强影响蜜蜂繁殖产出的假设（一个关键假设），我们将使用人工鸟巢陷阱来测量一组本地蜜蜂物种的繁殖产出随时间的变化。最后，为了探讨新蜜蜂物种引入的影响，我们将利用最近在不列颠哥伦巴省低陆平原意外引入的一种新的通才传粉媒介——普通东部大黄蜂（Bombus impatiens），来研究干扰对蜜蜂群落网络动态的影响。

Plants form the basis of most terrestrial ecosystems. Approximately 85% of plant species require an animal pollinator to reproduce and persist. However, due to a plethora of largely human driven stressors, pollinators are considered to be at risk globally, with potentially devastating consequences for global ecosystems. Over the past few decades, ecologists have produced a body of literature linking anthropogenic stressors to declining abundance and diversity of pollinator communities, but much less attention has been paid to the impacts of such changes for plant-pollinator interactions. Nonetheless, adding flowering plants to a community is an increasingly common restoration approach, with the goal of enhancing plant-pollinator interactions across a variety of ecosystems. Surprisingly, a recent meta-analysis found no consistent impact of such planting schemes (i.e., hedgerows or floral strips) on the pollination of nearby plants, indicating that there are many gaps in our understanding of how changes to either plant or pollinator communities impact their interaction networks and affect pollination services. The proposed research program will make use of a park restoration scheme recently initiated across the City of Vancouver. My long-term objective is to improve our understanding of how enhancements to the local plant community can impact the growth, stability and persistence of plant-pollinator interactions, which has policy implications for how ecosystems are managed. I hypothesize that the variation in outcomes is partly due to a lack of attention to trait matching between enhancements and the existing community. Ideally, enhancing plant communities will lead to increased colonization and reproduction by local pollinator species, thereby increasing the diversity and strength of their interaction networks. In order to test the long-term dynamics of plant-pollinator interactions, we will gather detailed information about plant traits and pollination networks at treatment (wildflower-enhanced) parks and compare them to control parks over multiple seasons. Using information about the stability of the networks based on their modularity (degree to which the network is composed of interacting subunits) and nestedness (degree to which internal networks are a subset of a larger network), we will examine how networks change over time following enhancements with varying plant-pollinator trait overlap. To test the hypothesis that floral enhancements impact bee reproductive output (a key assumption), we will use artificial nest traps to measure changes in the reproductive output of a set of local native bee species over time. Finally, to explore the impacts of novel bee species introductions, we will use the recent accidental greenhouse introduction of a new species of generalist pollinator, the common eastern bumblebee (Bombus impatiens) to the lower mainland of BC in order to study the impacts of disturbance to the bee community on network dynamics.