Temporal dynamics of plant-soil feedbacks and community consequences during Bromus inermis invasion

  • Author / Creator
    Salimbayeva, Karina
  • Invasive plant species often come to dominate the community where they have become introduced, posing a serious threat to plant diversity and ecosystem functions. Yet, the long-term dynamics and impacts of invasive species do not necessarily remain constant and may attenuate over time due to stabilizing mechanisms of plant-soil feedbacks. In this study, I first explored temporal dynamics of plant-soil feedbacks for the invader Bromus inermis (Leyss.) to determine whether invasive species accumulate negative plant-soil feedbacks over time. To fully capture all of the variations in plant-soil feedbacks for B. inermis, I used the combined strategy pairing field study with controlled conditions of the greenhouse environment to estimate B. inermis dynamics in natural systems while separating the potential drivers of plant-soil feedbacks. I found that B. inermis experience weakly negative to neutral plant-soil feedbacks in the early stages of invasion, but develops strongly negative plant-soil feedbacks over time. Contrary to our expectations, these shifts in the strength and directions of plant-soil feedbacks for B. inermis were not fully mediated by soil microbial communities of invaded
    areas. Second, I tested for environmental context dependence of plant-soil feedbacks for B. inermis by estimating changes in resource availability of invaded areas in relation to B. inermis residence time. The resource availability of B. inermis-invaded areas was at least partially associated with temporal dynamics of plant-soil feedbacks, where the increase in phosphorus availability and lower light access resulted in stronger, more negative plant-soil feedbacks for B. inermis. Last, I evaluated whether accumulation of negative plant-soil feedbacks for B.
    inermis can facilitate resident species recovery in invaded areas and result in lower B. inermis performance and dominance over time. No decline in B. inermis performance has been observed. Instead, B. inermis increased in shoot biomass production and allocated towards more vegetative reproduction under the effect of stronger negative plant-soil feedbacks. I also found that accumulation of negative plant-soil feedbacks for B. inermis was positively associated with recovery of species diversity but other factors of invaded areas can overcome the effect of plant-soil feedbacks and further mediate negative impacts of B. inermis invasion. The responses observed in this study suggest that at least in Alberta, B. inermis may accumulate stronger negative plant-soil feedbacks over time while still being dominant within a community. Yet, environmental context dependence of these plant-soil feedbacks can help us to predict under which conditions invasive species tend to experience more negative plant-soil feedbacks, allowing us to take advantage of invasive forage species while preventing/reducing their impact on biodiversity.

  • 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.