D3124: Effects of plant architecture on leaf tier community assembly and overall arthropod diversity

Diverse arthropod communities serve as prey for a variety of animals, including birds, small mammals, and other taxa, and play an essential role in supporting ecosystem services, such as nutrient cycling, pollination, and decomposition. With anthropogenic climate change, global insect communities are declining, threatening many organisms that rely on diverse insect communities and insect-mediated ecosystem services. Consequently, it is essential to understand factors that promote diverse arthropod communities, including habitat heterogeneity, which can be generated through the activities of ecosystem engineers. By modifying or creating habitats used by other species, ecosystem engineers alter the local availability of biotic and abiotic resources, dramatically increasing species diversity in those habitats. Leaf-tying caterpillars (Lepidoptera) are ecosystem engineers that influence community structure and locally increase species richness of leaf-chewing herbivores and other arthropods by sewing overlapping leaves together. While leaf-tying caterpillars are common on a variety of plant species, their ability to modulate local patterns of insect herbivore diversity and the effects of plant architecture on leaf tier communities across different host plants remain unclear. This study documents how plant architecture and leaf tie availability affect plant-level arthropod diversity across four different tree species that do not have a well described leaf tier community. We found that plant architecture strongly influences leaf tier communities and overall arthropod diversity, although the magnitude of this effect varies across host plants. Leaf ties more strongly increased herbivore richness during dry and hot periods when risk of desiccation is high, emphasizing their importance with respect to climate change.