INVASIVE LIANA HEDERA HELIX (ENGLISH IVY) IMPACTS ON ECOLOGICAL CHARACTERISTICS AND NUTRIENT CYCLING IN BALTIMORE FOREST PATCHES

Abstract

The effects of invasive plants on forest ecology and nutrient cycling are highly variable and poorly understood. Many studies have found that species and location make each plant invasion unique. Thus, studying invasive plants on the species and local level is necessary to understand how they impact ecosystems and how to manage them. Ninety-four percent of forest patches in Baltimore contain invasive plants. Hedera helix is one of the most prominent. My study explores how different characteristics and intensities of H. helix invasion impact ecology and nutrient cycling in Baltimore forest patches. I analyzed canopy structure, litter properties, soil properties, and steps of C and N cycling in forest patch plots. I compared findings across the invasion characteristics: presence, canopy invasion intensity, and ground cover presence. My study revealed that invasion characteristics and location strongly influence the impact of H. helix on Baltimore forest patch plots. The presence of ground cover appeared to be dictated by soil hydrology, which varied by location. Invaded plots with ground cover had significantly altered soil properties, increased soil respiration rates (2.86 times greater than control plots, p = 0.047), and may have increased decomposition rates. These differences in C cycling metrics appear to be driven by altered soil temperature, structure, and chemistry (i.e., 1.62 times more TN than control plots, p = 0.022). Canopy invasions may have caused tree loss and altered canopy structure, which indicate potentially negative consequences for forest patch ecology in the future. pH may have been higher in the presence of H. helix (1.17 times higher pH than control plots, p = 0.090). Several ecological characteristics and nutrient cycling variables may have also been more variable in the presence of H. helix. No significant differences were detected in N cycling due to invasion. These findings can help Baltimore forest patch managers to assess problematic H. helix invasions and allocate resources to control it when necessary. They also lay out further groundwork for plant invasion research, demonstrating the necessity of species-specific, location-specific studies.