Mangrove Pollinator Functional Diversity Decreases With Patch Size and Landscape Anthropization

Abstract

The impact of land use changes on pollinator diversity can vary depending on factors such as the size of remaining natural habitat patches, the type and intensity of anthropogenic activities, and the functional composition of pollinator communities. This understanding is particularly crucial for mangrove ecosystems, which are critically endangered by human activities and prioritized in global conservation strategies. This study investigates how anthropization affects mangrove pollinator diversity by examining how pollinators with different functional traits respond to variations in mangrove patch size and anthropogenic changes in the surrounding landscape matrix. We found that overall pollinator abundance, richness, and diversity increased in smaller mangrove patches, potentially helping to mitigate negative effects such as inbreeding and genetic drift—common in naturally patchy and isolated mangrove populations. However, these pollinator metrics declined with increasing landscape anthropization, with notably lower values in urbanized landscapes compared to agricultural ones, despite the smaller patch sizes in more anthropized settings. This negative trend was consistent across pollinators with varying traits, though the magnitude of the effect differed among pollinator groups. Ground-nesting and exposed-nesting pollinators were most influenced by patch size, while lepidopterans and wasps, as well as species with either very small or large body sizes, solitary behavior, and nesting in exposed sites or cavities, were most affected by landscape anthropization. Conservation and management efforts should prioritize habitat provisioning for these most impacted groups to support mangrove ecosystem resilience.