The effects of invasive slender false-brome (Brachypodium sylvaticum) on forest ecosystem function in western New York

Abstract

The interconnectedness of the modern world has led to the spread of species outside of their normal range. Some species become invasive and can impact ecosystems by changing soil, water, and nutrient dynamics. Disrupting these important ecosystem processes can facilitate further invasion. Slender false-brome (Brachypodium sylvaticum) is an exotic bunchgrass that is invasive in North America. Its encroachment into forest understories may have implications for ecosystem processes and characteristics. The goal of this study was to understand the impacts of slender false-brome on forest ecosystem function. This study took place within two forests in western New York, one at Taughannock Falls State Park (TFSP), Trumansburg, and one in Danby State Forest (DSF), Danby. Replicate paired plots with and without B. sylvaticum were selected in each forest; each pair was matched by canopy cover and canopy type. In plots I measured vegetation, soil physical and chemical characteristics, soil moisture, soil respiration, and decomposition of leaf litter. I used generalized linear mixed models to determine variables that were the strongest predictors of soil nutrients, soil respiration, and leaf litter decomposition. All soil characteristics measured were significantly different between invaded and uninvaded plots except bulk density. At TFSP, invaded plots were enriched with organic matter (OM) and total nitrogen (TN). At DSF, invaded plots were enriched with phosphorus (P). Invaded plots at both sites had greater cation (Mg, Ca, K) concentrations, pH, and bulk density, and soil respiration and decomposition rates also increased in response to B. sylvaticum invasion. My results demonstrate that Brachypodium sylvaticum invasion significantly alters ecosystem processes, although initial site conditions do affect the magnitude and trend of some changes. Overall, B. sylvaticum has impacts on ecosystem processes like other flagship invasive species, however the impacts seem to change based on initial site conditions. I found that sites like Danby State Forest and Taughannock Falls State Park are at risk of changes in soil nutrients, soil respiration, and decomposition. A greater diversity of sites needs to be investigated to determine if other types of ecosystems are at risk from Brachypodium sylvaticum.