Insect pollinators provide a crucial ecosystem service, but are under threat. Urban areas could be important for pollinators, though their value relative to other habitats is poorly known. We compared pollinator communities using quantified flower-visitation networks in 36 sites (each 1 km2) in three landscapes: urban, farmland and nature reserves. Overall, flower-visitor abundance and species richness did not differ significantly between the three landscape types. Bee abundance did not differ between landscapes, but bee species richness was higher in urban areas than farmland. Hoverfly abundance was higher in farmland and nature reserves than urban sites, but species richness did not differ significantly. While urban pollinator assemblages were more homogeneous across space than those in farmland or nature reserves, there was no significant difference in the numbers of rarer species between the three landscapes. Network-level specialization was higher in farmland than urban sites. Relative to other habitats, urban visitors foraged from a greater number of plant species (higher generality) but also visited a lower proportion of available plant species (higher specialization), both possibly driven by higher urban plant richness. Urban areas are growing, and improving their value for pollinators should be part of any national strategy to conserve and restore pollinators.
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机译:昆虫传粉者提供了至关重要的生态系统服务,但受到威胁。尽管传授媒介相对于其他栖息地的价值鲜为人知,但对于传粉媒介而言,城市地区可能很重要。我们使用量化的花卉探访网络在城市,农田和自然保护区三个景观的36个地点(每个1 km 2 sup>)中比较了授粉媒介群落。总体而言,这三种景观类型之间的访花者丰度和物种丰富度没有显着差异。蜜蜂的丰度在不同的景观之间没有差异,但是城市地区的蜜蜂物种丰富度高于农田。在农田和自然保护区中,蚜蝇的丰度高于城市地区,但物种丰富度没有显着差异。尽管城市授粉媒介在空间上的分布比农田或自然保护区中的更为均匀,但三种景观之间稀有物种的数量没有显着差异。农田的网络级专业化程度高于城市地区。相对于其他栖息地,城市游客从更多的植物种类中觅食(较高的普遍性),但也访问了较少的可用植物种类(较高的专业化程度),这都可能是由于城市植物丰富度较高所致。城市地区正在增长,提高其对传粉媒介的价值应成为任何保护和恢复传粉媒介的国家战略的一部分。
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