Net Ecosystem Exchange of Carbon dioxide in a Temperate Poor Fen: a Comparison of Automated and Manual Chamber Techniques |
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Authors: | Email author" target="_blank">Elizabeth?H?BurrowsEmail author Jill?L?Bubier Andrew?Mosedale George?W?Cobb Patrick?M?Crill |
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Institution: | (1) Environmental Studies Program, Department of Earth and Environment, Mount Holyoke College, 50 College Street, 01075 South Hadley, MA, USA;(2) Department of Bioresource Engineering, Oregon State University, 116 Gilmore Hall, 97331 Corvallis, OR, USA;(3) Complex Systems Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, 03824 Durham, NH, USA;(4) Department of Mathematics and Statistics, Mount Holyoke College, 50 College Street, 01075 South Hadley, MA, USA;(5) Department of Geology and Geochemistry, University of Stockholm, 106 91 Stockholm, Sweden |
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Abstract: | We used five analytical approaches to compare net ecosystem exchange (NEE) of carbon dioxide (CO2) from automated and manual static chambers in a peatland, and found the methods comparable. Once per week we sampled manually
from 10 collars with a closed chamber system using a LiCor 6200 portable photosynthesis system, and simulated four photosynthetically
active radiation (PAR) levels using shrouds. Ten automated chambers sampled CO2 flux every 3 h with a LiCor 6252 infrared gas analyzer. Results of the five comparisons showed (1) NEE measurements made
from May to August, 2001 by the manual and automated chambers had similar ranges: −10.8 to 12.7 μmol CO2 m−2 s−1 and −17.2 to 13.1 μmol CO2 m−2 s−1, respectively. (2) When sorted into four PAR regimes and adjusted for temperature (respiration was measured under different
temperature regimes), mean NEE did not differ significantly between the chambers (p < 0.05). (3) Chambers were not significantly different in regression of ln( − respiration) on temperature. (4) But differences
were found in the PAR vs. NEE relationship with manual chambers providing higher maximum gross photosynthesis estimates (GPmax), and slower uptake of CO2 at low PAR (α) even after temperature adjustment. (5) Due to the high variability in chamber characteristics, we developed an equation
that includes foliar biomass, water table, temperature, and PAR, to more directly compare automated and manual NEE. Comparing
fitted parameters did not identify new differences between the chambers. These complementary chamber techniques offer a unique
opportunity to assess the variability and uncertainty in CO2 flux measurements. |
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Keywords: | Automated chambers Chamber comparison CO2 flux Fen Net ecosystem CO2 exchange Wetland |
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