Turbulence considerations for comparing ecosystem exchange over old-growth and clear-cut stands for limited fetch and complex canopy flow conditions

Sonia Wharton; Matt Schroeder; Kyaw Tha Paw U; Matthias Falk; Ken Bible

doi:10.1016/j.agrformet.2009.04.002

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Turbulence considerations for comparing ecosystem exchange over old-growth and clear-cut stands for limited fetch and complex canopy flow conditions

Formally Refereed

Authors:

Sonia Wharton, Matt Schroeder, Kyaw Tha Paw U, Matthias Falk, Ken Bible

Year:

2009

Type:

Scientific Journal

Station:

Pacific Northwest Research Station

DOI:

https://doi.org/10.1016/j.agrformet.2009.04.002

Source:

Agricultural and Forest Meterology. 149: 1477-1490

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Abstract

Carbon dioxide (CO₂), water vapor, and energy fluxes were measured using eddy covariance (EC) methodology over three adjacent evergreen forests in southern Washington State to identify stand-level age-effects on ecosystem exchange. The sites represent Douglas-fir forest ecosystems at two contrasting successional stages: old-growth (OG) and early seral (ES). We show an alternative approach to the usual friction velocity method for determining periods of adequate atmospheric boundary layer mixing based on the ratio of mean horizontal or vertical windflow to a modified turbulent kinetic energy scale. This new parameter in addition to footprint modeling showed that daytime CO₂ fluxes in small clearcuts (

Keywords

old growth, clearcut, Douglas-fir, ecosystem exchange, fetch, footprint modeling, turbulence statistics

Citation

Wharton, S.; Schroeder, M.; Paw U, K.T.; Falk, M.; Bible, K. 2009. Turbulence considerations for comparing ecosystem exchange over old-growth and clear-cut stands for limited fetch and complex canopy flow conditions. Agricultural and Forest Meterology. 149: 1477-1490.