Quantifying the importance of tree floral resources for pollinators in urban landscapes

全球城市化进程正在加速，预计到2050年，城市人口将增加25亿(1)。因此，预计土地利用变化将相应增加。城市化往往与自然生境的碎片化和破坏导致的生物多样性下降有关(2)。然而，一些传粉者种群可能依赖于城市地区作为重要的栖息地(3，4)。许多研究已经调查了土地利用变化对传粉者的影响，但关于树木植物资源对传粉者的重要性的认识存在差距。尽管树木在城市地区很常见，但它们的资源经常被忽视。在确实考虑城市树木的研究中，只对从地面可以接触到的低垂的树叶进行采样(5)。由于这种知识差距，为传粉者制定有效的城市保护战略是具有挑战性的。城市树木面临许多威胁，如城市热岛效应、有限的生根空间和不透水的表面(6)。高昂的维护费用也导致许多行道树被砍伐。因此，必须填补这一知识空白，并确定城市传粉者在多大程度上利用树木花卉资源，以及与其他城市植物相比，树木对传粉者的重要性有多大。研究问题：1.城市景观中树木产生了多少花粉和花蜜资源？2.传粉者如何利用城市景观中的城市树木资源？3.城市树木对传粉者的重要性是什么？这些传粉者对城市树木的重要性是什么？4.城市树木的增加如何影响城市尺度的植物传粉者群落的健壮性？研究方法：这项研究将跨越英国的两个田野季节。

Urbanisation is accelerating globally, with the urban population projected to increase by 2.5 billion by 2050 (1). It is therefore expected that land-use change will increase correspondingly. Urbanisation is often linked to declines in biodiversity due to fragmentation and destruction of natural habitats (2). However, some pollinator populations may depend on urban areas as important habitats (3, 4).Many studies have investigated the impacts of land-use change on pollinators, however there is a knowledge gap surrounding the importance of tree floral resources for pollinators. Despite trees being common in urban areas their resources are frequently overlooked. In studies which do consider urban trees, only low-hanging foliage accessible from the ground is sampled (5). As a consequence of this knowledge gap, it is challenging to create effective urban conservation strategies for pollinators.Urban trees face many threats such as effects of the urban heat island, restricted rooting space, and water impervious surfaces (6). High maintenance costs have also led to the felling of many street trees. It is therefore essential to fill this knowledge gap and determine to what extent urban pollinators use tree floral resources and how important trees are for pollinators in comparison to other urban plants. Research Questions:1. How much pollen and nectar resources are produced by trees in urban landscapes? 2. How do pollinators use urban tree resources in urban landscapes?3. What is the importance of urban trees for pollinators, and what is the importance of these pollinators for urban trees?4. How does the addition of urban trees affect city-scale plant-pollinator community robustness? Research Methods:This research will span two field seasons in the UK.