A practical approach for uncertainty quantification of high‐frequency soil respiration using Forced Diffusion chambers. Issue 1 (28th January 2015)

• Record Type: Journal Article
• Authors: Lavoie, Martin; Phillips, C. L.; Risk, David
• Is Part Of: Journal of geophysical research. Volume 120:Issue 1(2015:Mar.)
• Page Start: 128
• Page End: 146
• Publication Date: 2015-01-28
• Subjects: Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2014JG002773
• Languages: English
• ISSNs: 2169-8953

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>This paper examines the sources of uncertainty for the Forced Diffusion (FD) chamber soil respiration (<italic>R<sub>s</sub></italic>) measurement technique and demonstrates a protocol for uncertainty quantification that could be appropriate with any soil flux technique. Here we sought to quantify and compare the three primary sources of uncertainty in <italic>R<sub>s</sub></italic>: (1) instrumentation error; (2) scaling error, which stems from the spatial variability of <italic>R<sub>s</sub></italic>; and (3) random error, which arises from stochastic or unpredictable variation in environmental drivers and was quantified from repeated observations under a narrow temperature, moisture, and time range. In laboratory studies, we found that FD instrumentation error remained constant as <italic>R<sub>s</sub></italic> increased. In field studies from five North American ecosystems, we found that as <italic>R<sub>s</sub></italic> increased from winter to peak growing season, random error increased linearly with average flux by about 40% of average <italic>R<sub>s</sub></italic>. Random error not only scales with soil flux but scales in a consistent way (same slope) across ecosystems. Scaling error, measured at one site, similarly increased linearly with average <italic>R<sub>s</sub></italic>, by about 50% of average <italic>R<sub>s</sub></italic>. Our findings are consistent with previous findings for both soil fluxes and eddy covariance fluxes across other northern temperate ecosystems that showed random error scales linearly with flux magnitude with a slope of ~0.2. Although the mechanistic basis for this scaling of random error is unknown, it is suggestive of a broadly applicable rule for predicting flux random error. Also consistent with previous studies, we found the random error of FD follows a Laplace (double‐exponential) rather than a normal (Gaussian) distribution.</p> </abstract>