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Harvard Forest Symposium Abstract 2019

  • Title: Eddy flux ensemble averaging to diagnose short-term forest responses
  • Primary Author: David Fitzjarrald (SUNY at Albany)
  • Abstract:

    We compare two studies performed using data from the EMS tower, one published with C-H Lu in 1994 and one from 2019. In the first we showed how to parse the 'raw' eddy flux data to infer the importance of large eddies in effecting energy and carbon fluxes at the eddy footprint. In the second, published with S. Kivalov, we examine several years' worth of 10Hz signals to determine the response of the whole canopy to step changes in light caused by the passage of low cumulus clouds. By employing a 'classic' ensemble approach, not normally attempted with field data, we were able to demonstrate that the well-known carbon uptake and water use efficiency enhancement on cloudy days can plausible be the result of uptake during the sunny interval, with enhanced WUE during the shadow period. We confirm, at the whole-canopy scale, the McAusland et al. (2015) argument that water and carbon uptake cannot both be optimized during dynamic photosynthesis, an argument up to now based on modeling or leaf-scale studies alone..

  • Research Category: Forest-Atmosphere Exchange