Modelling Impacts of Producer Turnover Time and Elevated Atmospheric Carbon Dioxide on Food Chains

  • Author / Creator
    Davies, Colleen M
  • Ecological stoichiometry is a framework that allows explicit consideration of nutrient restrictions on growth, and can be used to answer important ecological questions. First, we consider the impact of the turnover rate of producer biomass on ecosystems, since it is usually much faster in aquatic ecosystems than terrestrial. The WKL model uses ecological stoichiometry to describe the flow of phosphorus and carbon through a producer-grazer system, hence varying the model parameters allows for analysis of different ecosystems of this type. Here we explore the impacts of the intrinsic growth rate of the producer and the maximal ingestion rate of the grazer on these dynamics. Simulations show that for low intrinsic growth rate and maximal ingestion rate, the grazer goes extinct; for higher values, coexistence occurs in oscillations. Analyses show that the persistence of terrestrial grazers despite lower turnover times likely relies on additional factors, such as light intensity and grazer loss rate.

    Second, we extend the WKL model to allow for consideration of the impacts of elevated atmospheric carbon dioxide concentration on producer-grazer dynamics. Three new models are developed, with varying amounts of system openness to carbon as well as consideration of different impacts of elevated atmospheric carbon dioxide concentration on photosynthesis. The most basic of these models is analysed further using primarily local bifurcation analysis. Overall, these analyses show that increased carbon sequestration and decreased stoichiometric quality of producers would require sufficient amounts of other factors necessary for photosynthesis.

  • Subjects / Keywords
  • Graduation date
    Fall 2020
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
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