Invasive species have severe impacts on the ecosystem, including drastically altering the plant community which in turn impacts soil microbial communities. These changes can then have cascading effects on ecosystem services. Despite increasing knowledge of how invasive plants can change plant community structure and soil properties, little is known about how multiple invasive plants influence ecosystem services. To investigate how invasive plant species impact ecosystem services, 20-26 soil cores were collected weekly for 26 weeks in a grassland, near Saskatoon, Canada, undergoing invasion by smooth brome (Bromus inermis) and five other invasive species including Canada thistle, Kentucky bluegrass and Perennial Sow Thistle. Greenhouse gas emissions, extracellular enzymes, soil aggregate structure, and soil properties were measured for each sample, as well as glyphosate degradation rates. Additionally, plant and litter surveys were conducted weekly in each in each plot.
Results/Conclusions
Invasive plant biomass increased throughout the growing season with senescence (September 18-November 4) having a higher proportion of invaded biomass. Invasive plant biomass significantly increased the large aggregate size (p<0.05), changing soil structure relative to plots with more native biomass. Greenhouse gas emissions were primarily driven by soil properties as well as field temperature and moisture with increased carbon dioxide and methane emissions in plots with more invasive plant biomass. Similarly, extracellular enzyme activity was driven by soil pH and changes in soil structure, with higher dehydrogenase and potential nitrification activity in invaded plots. Glyphosate degradation was driven by invasive biomass, temperature, moisture and soil pH, with plots with more native biomass had higher rates of glyphosate degradation. Smooth brome invasion has impacts on soil structure which in turn, drive changes ecosystem services. Changes in soil structure will have lasting impacts on this ecosystem and make restoration of native grassland species more difficult, leading to long-term changes in ecosystem functioning. Loss of native prairie ecosystems could exacerbate climate change due to changes in ecosystem services.