Monitoring Phenology of Boreal Trees Using Remote Sensing

• Author / Creator

  Springer, Kyle

• Terrestrial vegetation contributes strongly to dynamic biosphere-atmosphere exchanges of mass and energy, through activities such as photosynthesis, that help shape the Earth’s climate. The boreal forest is located in high latitudes and subject to large seasonal temperature fluctuations and a changing climate. Understanding the response of the boreal forest to seasonal and climate changes requires a means of effectively monitoring vegetation phenology at large spatial and temporal scales. Optical remote sensing can be applied at such scales, providing a powerful means of observing how ecosystems respond to changing environmental conditions. However, continued work that integrates both optical remote sensing and plant physiology at multiple scales is necessary to correctly apply and interpret large scale remote sampling of vegetation. Key questions regarding the application of optical remote sensing across ecosystems remain unanswered: 1) which remote sensing metrics are most effective at monitoring phenology of different functional types? and 2) how do these remote sensing metrics relate to actual changes in plant physiology when sampling different vegetation?
  To address these questions, experimental forest stands for several boreal tree species, both evergreen and deciduous were established in pots in Edmonton, Alberta, Canada, allowing for continuous monitoring across seasons using a variety of metrics to track phenology of representative boreal vegetation at multiple scales. This involved the use of different optical indices: the normalized difference vegetation index (NDVI), the photochemical reflectance index (PRI), the chlorophyll/carotenoid index (CCI), and steady-state chlorophyll fluorescence (FS), as an analogue of solar-induced fluorescence (SIF). These optical metrics were then compared to actual rates of photosynthesis to determine their efficacy in tracking seasonal changes in photosynthetic activity, or photosynthetic phenology. Results indicated that NDVI and PRI exhibited a complementary ability to monitor photosynthetic phenology of both evergreen and deciduous functional types. NDVI effectively tracked photosynthetic phenology of deciduous species, but less so for evergreens, while PRI closely paralleled photosynthetic phenology of evergreens, but less so for deciduous species. CCI showed strong parallels with photosynthetic activity in both evergreen and deciduous species, with FS showing a similar ability. These results indicated subtle differences in seasonal patterns of optical metrics and photosynthetic activity across and within functional types. Overall, these results revealed the efficacy of different remote sensing metrics at tracking photosynthetic phenology of different boreal tree species. This project provides an important foundation for the assessment of plant physiology by means of optical remote sensing, expanding the value of large-scale ecosystem monitoring.

• Subjects / Keywords

  • Boreal
  • PRI
  • Remote Sensing
  • Chlorophyll Fluorescence
  • NDVI
  • CCI
  • Photosynthesis
  • Phenology

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3K64B87T

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.