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Harvard Forest Symposium Abstract 2014

  • Title: Radiometric and imaging sensor-based phenology of a mixed hardwood forest canopy
  • Primary Author: Andrew Richardson (Northern Arizona University)
  • Additional Authors: Donald Aubrecht (Harvard University); Koen Hufkens (Harvard University)
  • Abstract:

    To better understand the patterns of seasonal variation in canopy structure and function, and how relationships between structure and function scale from leaves to ecosystems, we began to install an extensive set of radiometric instruments and imaging sensors on the Harvard Forest Barn Tower beginning in 2011.

    We have continued to expand the data available from instruments. During the 2013 growing season, three imaging sensors were mounted: two thermal infrared (TIR) cameras and one hyperspectral camera, all with fields-of-view that overlap our other digital cameras. The TIR cameras enable us to measure leaf and branch skin temperature, without installing an array of thermocouples in the canopy (Figure 1). The two TIR cameras give us canopy-scale and leaf-scale images (Figure 2). We intend to use this dataset to provide additional insight on water stress, as well as better characterize energy fluxes from the canopy.

    The hyperspectral camera at the barn tower records image “cubes” that provide spatial maps of spectra from 380-1020 nm in 5 nm bands. We have a Spectralon reference panel in view of the camera, enabling us to calculate reflectance values for the foliage. From this data, we plan to independently confirm measurements from our standard PhenoCam digital cameras as well as investigate differential vegetation indices that might capture seasonal transitions better than the green chromatic coordinate (GCC) calculated from the digital camera images.

    In this coming season, we will fill out our dataset with ground truth measurements and eddy flux data. A new eddy covariance flux system will be mounted on the Barn Tower this spring, providing measurements of carbon, water, and energy fluxes. Our summer REU project will entail weekly vegetation sampling from canopies that are included in the fields-of-view of all our cameras and instruments. We will be taking measurements of conductance, water potential, and leaf color. These data will be combined with our radiation measurements to better characterize driving factors and constrain models of canopy-level processes.

  • Research Category: Ecological Informatics and Modelling, Forest-Atmosphere Exchange

  • Figures:
  • 2014 HF symposium figure1.jpg
    2014 HF symposium figure2.jpg