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Harvard Forest REU Symposium Abstract 2021

  • Title: Impact of spatial ecology on co-located Eddy Covariance Flux Towers
  • Author: Benjamin Glass (Middlebury College)
  • Abstract:

    In New England, temperate forests act as important regional carbon sinks. However, the rate of carbon dioxide uptake within these forests varies over space. This research aimed to improve Harvard Forest’s carbon flux models by accounting for variations in spatial ecology around two separate, but closely-located, Eddy Flux Towers in Harvard Forest. This research explored (a) how spatial variation affected each carbon flux tower individually, and (b) whether the two tower measurements similarly covaried due to spatial variation. Using an established Flux Footprint Prediction (FFP) model, I derived spatial footprints for hourly carbon flux measurements at EMS and NEON towers from the last 4 years (2017-2020). I then extracted summary statistics on spatial ecological characteristics (species percentages, canopy height, and spectral indices) of each hourly footprint and calculated percentage overlap of tower footprints. I found that the absolute difference in flux measurement between towers decreases as the spatial overlap of tower footprints increase. I also found that carbon dioxide flux is negatively correlated to tasseled cap greenness during the growing season (May-September) in times of high temperature and light-availability. Carbon dioxide flux shows little relationship with canopy height and species distribution data. This is likely because the value ranges of these spatial data within EMS and NEON footprints are small. Measuring a more heterogeneous landscape would likely yield a more defined relationship. In general, accounting for spatial variability in Harvard Forest’s carbon flux models will allow researchers to model and forecast flux measurements more accurately. An accurate assessment of forest carbon uptake and emission is essential to understand the extent to which temperate forests can be utilized as a natural climate solution.

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