Spatiotemporal variability of the fraction of Photosynthetically Active Radiation (fPAR) in a mixed coniferous forest using Wireless sensor networks

  • Author / Creator
    Ke, Yuhui
  • Contemporary climate change has become rapid, and its impacts affect forest growth and productivity directly and indirectly through changes in temperature, precipitation, carbon dioxide, and other factors. Forest ecosystem plays an essential role in carbon exchange between the atmosphere and terrestrial. Green plants absorb carbon from the atmosphere through photosynthesis, whereas degradation and deforestation release carbon. Given appropriate and efficient management, forest can be a beneficial asset in climate mitigation. The fraction of photosynthetically active radiation (fPAR) is a fundamental term to quantifying light used by plants in photosynthesis. This term has been mainly derived from satellite data, but some inherent issues of satellite data limit the quality of long-term fPAR estimation. Advances in technology and the emergence of wireless sensor networks have allowed for long-term, continuous, high spatial and temporal fPAR measurements. In Chapter 1, the general methods of estimating fPAR are reviewed, and the importance of accurate fPAR estimation and factors that can cause measurement bias are explored. Needs for long-term fPAR study and its role in forest dynamics are proposed, and the research questions and hypotheses of this thesis are then posed.
    In Chapter 2, forest structure metrics, such as leaf area index (LAI), were extracted from the 3D point cloud developed by terrestrial laser scanning (TLS). In situ wireless sensor networks (WSNs) were used to collect continuous photosynthetically active radiation (PAR) in the mixed coniferous Graswang forest site and were calculated into fPAR. The spatial distribution of fPAR from 2016 to 2019 was compared and analyzed using Kriging interpolation to determine the spatiotemporal variation of fPAR in the mixed wood forest. Chi-square statistical test was performed to assess the significance of fPAR variation. To better understand the vertical forest structure of the study site, metrics such as LAI, centroid (Cx, Cy), and radius of gyration (RG) were interpolated to explore and understand the spatial forest structure variation. Forest inventory included tree species, diameter breast height (DBH), and mortality was documented. To assess the influence factors on fPAR, multiple correlation analyses was used between LAI, tree species type, mortality and fPAR.
    The third chapter of this thesis examined the significance of the results concluded in Chapter 2 and suggested the study's limitation. Potential future explorations are proposed, including the advance of wireless sensor networks outdoor performance and factors, such as mortality and drought, influence on the effect of LAI on fPAR in a coniferous and deciduous mixed forest.

  • Subjects / Keywords
  • Graduation date
    Spring 2022
  • 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.