Patterns of Non-Native Plants Among Native Grasslands in Alberta, Canada

  • Author / Creator
    Zapisocki, Zoey M.
  • Native grasslands are a fundamental part of Canada’s natural heritage, but these formerly extensive ecosystems have undergone declines due to grassland conversion and fragmentation. One threat to remaining native grasslands is invasion by non-native plants, which can outcompete native flora and negatively impact grassland integrity. This study identified patterns of non-native abundance, richness, and individual species occurrences among native grasslands in the Dry Mixedgrass (DMG), Mixedgrass (MG), Northern Fescue (NF), Central Parkland (CP), and Peace River Parkland (PRP) Natural Subregions of Alberta, Canada. Species composition, environmental, and anthropogenic data were collected for 86 plots across the Subregions. Generalized additive models (GAMs) and commonality coefficient analysis were used to identify the strongest predictors for relative cover and richness of non-native plants. In general, abundance and richness of non-native plants were positively linked to moisture and nutrient availability. Aridity and soil fertility were the best predictors across all plots, with mesic loamy grasslands being the most invaded. Patterns of invasion differed between Natural Subregions. In the DMG, relative non-native richness was associated with higher soil carbon content. In the CP, non-native plant abundance and richness was highest in fine-textured fertile soil, as well as on gentle slopes. In the PRP, relative non-native cover was highest on gentle slopes with low pH levels. Kentucky bluegrass (Poa pratensis L.) was the most frequent and abundant non-native plant in this study. Crested wheatgrass (Agropyron cristatum (L.) Gaertner) and smooth brome (Bromus inermis Leysser) were the next most abundant, occurring in clumped distributions in the DMG and CP, respectively. With relatively low cover, dandelion (Taraxacum officinale F.H. Wiggers) and goat’s beard (Tragopogon dubius Scopoli) were the next most frequent. Results suggest that environmental conditions best explain the patterns of non-native plants in Alberta grasslands. However, anthropogenic influences such as agricultural history and proximity, as well as individual species adaptations, may also play a role in the observed patterns. Future avenues for native grassland research include teasing out soil fertility effects and assessing the roles of topography or soil texture on invasion. The patterns of non-native plants identified in this study can also be considered by land managers who are tasked with prioritizing conservation efforts.

  • Subjects / Keywords
  • Graduation date
    Spring 2021
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.