Effects of Ecological Restoration on the Leaf-Litter Arthropod Community

Current ecological restoration and management programs in forests of the Chicago metropolitan region focus on the removal and control of invasive plant species as a high priority. Additional efforts, such as seeding and selective cutting and burning, aim to alter the composition of herbaceous vegetation and canopy species, with the goal of managing the plant communities. Leaf-litter arthropods are a source of high biodiversity, and as key members of the detrital food web, facilitate the decomposition of organic matter into simple compounds, thereby affecting nutrient cycling between above- and below-ground structures of the plant community. Changes in the plant community caused by both invasive plant species and land management techniques have the potential to alter the detrital community by modifying both the diversity and structure of the leaf litter. This dissertation research examines how the forest leaf-litter arthropod community responds to changing leaf-litter conditions influenced by restoration and management efforts. I investigated how land management and invasive plant leaf litter have impacted the arthropod community at three different scales. At the regional level, I studied how the management history of 28 woodland sites in 4 adjacent counties has affected the leaf litter and leaf-litter arthropod community structure. At the site and microhabitat scale, I researched the colonization and consumption patterns of arthropods on native and invasive litter monocultures and mixed litter treatments. The overall objective of this dissertation is to advance our existing body of knowledge of woodland restoration through four research projects. The first is a study to examine how the detritus-based arthropod community responds to woodland restoration history and individual leaf litter characteristics at 28 sites in northeastern Illinois; the second, I focused on determining if an introduced litter type from an invasive shrub, European Buckthorn (Rhamnus cathartica), impacts the arthropod leaf-litter colonization rate in a field experiment. In the third study, I investigate how an invasive plant species targeted in woodland restoration efforts, influences the consumption rates of major detritivores in a mixed-litter mesocosm study. Lastly, I examined how direct contact with the leaf litter of the invasive European Buckthron influences the palatability of native canopy species in a cafeteria-style food choice experiment. Finally, I coalesce the findings of the research projects into a general discussion and future research directions.