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Harvard Forest REU Symposium Abstract 2014

  • Title: Monitoring Spring Phenophase Transitions with UAV Imagery
  • Author: Sidni M Frederick (Harvard College (Harvard University))
  • Abstract:

    Recent warming trends associated with climate change have extended the growing season in temperate forests, pushing spring earlier and autumn later in the year. Monitoring arboreal seasonal transitions under these circumstances will help us to understand how forest ecosystem services are being impacted. UAVs, or unmanned aerial vehicles, have emerged as a helpful tool in the scientific community, and previous studies have documented their capacity to monitor changes in the forest canopy over time with digital photography. However, the question remains as to how phenological events determined from digital photography correlate to canopy physiology. I hypothesize that spring transition dates calculated from changes in the greenness of UAV-based imagery time series will correlate positively with observed transitions in leaf growth and development. I work with time series imagery of a portion of the Harvard Forest canopy taken using a digital camera mounted to a UAV with a pre-programmed flight path. I use Matlab scripts to calculate Green Chromatic Coordinate values for individual trees on different dates, and to calculate dates for the beginning, middle and end of spring based on thresholding and curve-fitting methods. I then compare these dates with spring transition dates from ground-level observations of leaf development. From my analysis, I expect to see a significant relationship between phenophase transitions calculated from UAV imagery and the progression of leaf growth relative to final size. With an understanding of the physiological events that UAV-based canopy imagery captures, we can better employ UAVs as ecological monitoring tools.

  • Research Category: Group Projects