Resolving systematic errors in estimates of net ecosystem exchange of CO<inf>2</inf> and ecosystem respiration in a tropical forest biome

Hutyra, LR; Munger, JW; Hammond-Pyle, E; Saleska, SR; Restrepo-Coupe, N; Daube, BC; de Camargo, PB; Wofsy, SC

Resolving systematic errors in estimates of net ecosystem exchange of CO<inf>2</inf> and ecosystem respiration in a tropical forest biome

Hutyra, LR Munger, JW Hammond-Pyle, E Saleska, SR Restrepo-Coupe, N

Daube, BC de Camargo, PB Wofsy, SC

Permalink

Publication Type:: Journal Article
Citation:: Agricultural and Forest Meteorology, 2008, 148 (8-9), pp. 1266 - 1279
Issue Date:: 2008-07-04

Closed Access

	Filename	Description	Size
	2010001589OK.pdf		1.32 MB	Adobe PDF	View/Open

Copyright Clearance Process

Recently Added
In Progress
Closed Access

This item is closed access and not available.

Full metadata record

Field	Value	Language
dc.contributor.author	Hutyra, LR	en_US
dc.contributor.author	Munger, JW	en_US
dc.contributor.author	Hammond-Pyle, E	en_US
dc.contributor.author	Saleska, SR	en_US
dc.contributor.author	Restrepo-Coupe, N https://orcid.org/0000-0003-3921-1772	en_US
dc.contributor.author	Daube, BC	en_US
dc.contributor.author	de Camargo, PB	en_US
dc.contributor.author	Wofsy, SC	en_US
dc.date.issued	2008-07-04	en_US
dc.identifier.citation	Agricultural and Forest Meteorology, 2008, 148 (8-9), pp. 1266 - 1279	en_US
dc.identifier.issn	0168-1923	en_US
dc.identifier.uri	http://hdl.handle.net/10453/14689
dc.description.abstract	The controls on uptake and release of CO2 by tropical rainforests, and the responses to a changing climate, are major uncertainties in global climate change models. Eddy-covariance measurements potentially provide detailed data on CO2 exchange and responses to the environment in these forests, but accurate estimates of the net ecosystem exchange of CO2 (NEE) and ecosystem respiration (Reco) require careful analysis of data representativity, treatment of data gaps, and correction for systematic errors. This study uses the comprehensive data from our study site in an old-growth tropical rainforest near Santarem, Brazil, to examine the biases in NEE and Reco potentially associated with the two most important sources of systematic error in Eddy-covariance data: lost nighttime flux and missing canopy storage measurements. We present multiple estimates for the net carbon balance and Reco at our site, including the conventional "u* filter", a detailed bottom-up budget for respiration, estimates by similarity with 222Rn, and an independent estimate of respiration by extrapolation of daytime Eddy flux data to zero light. Eddy-covariance measurements between 2002 and 2006 showed a mean net ecosystem carbon loss of 0.25 ± 0.04 μmol m-2 s-1, with a mean respiration rate of 8.60 ± 0.11 μmol m-2 s-1 at our site. We found that lost nocturnal flux can potentially introduce significant bias into these results. We develop robust approaches to correct for these biases, showing that, where appropriate, a site-specific u* threshold can be used to avoid systematic bias in estimates of carbon exchange. Because of the presence of gaps in the data and the day-night asymmetry between storage and turbulence, inclusion of canopy storage is essential to accurate assessments of NEE. We found that short-term measurements of storage may be adequate to accurately model storage for use in obtaining ecosystem carbon balance, at sites where storage is not routinely measured. The analytical framework utilized in this study can be applied to other Eddy-covariance sites to help correct and validate measurements of the carbon cycle and its components. © 2008 Elsevier B.V. All rights reserved.	en_US
dc.relation.ispartof	Agricultural and Forest Meteorology	en_US
dc.relation.isbasedon	10.1016/j.agrformet.2008.03.007	en_US
dc.subject.classification	Meteorology & Atmospheric Sciences	en_US
dc.title	Resolving systematic errors in estimates of net ecosystem exchange of CO<inf>2</inf> and ecosystem respiration in a tropical forest biome	en_US
dc.type	Journal Article
utslib.citation.volume	8-9	en_US
utslib.citation.volume	148	en_US
utslib.for	0705 Forestry Sciences	en_US
utslib.for	04 Earth Sciences	en_US
utslib.for	06 Biological Sciences	en_US
utslib.for	07 Agricultural and Veterinary Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
utslib.copyright.status	closed_access
pubs.issue	8-9	en_US
pubs.publication-status	Published	en_US
pubs.volume	148	en_US

Abstract:

The controls on uptake and release of CO2 by tropical rainforests, and the responses to a changing climate, are major uncertainties in global climate change models. Eddy-covariance measurements potentially provide detailed data on CO2 exchange and responses to the environment in these forests, but accurate estimates of the net ecosystem exchange of CO2 (NEE) and ecosystem respiration (Reco) require careful analysis of data representativity, treatment of data gaps, and correction for systematic errors. This study uses the comprehensive data from our study site in an old-growth tropical rainforest near Santarem, Brazil, to examine the biases in NEE and Reco potentially associated with the two most important sources of systematic error in Eddy-covariance data: lost nighttime flux and missing canopy storage measurements. We present multiple estimates for the net carbon balance and Reco at our site, including the conventional "u* filter", a detailed bottom-up budget for respiration, estimates by similarity with 222Rn, and an independent estimate of respiration by extrapolation of daytime Eddy flux data to zero light. Eddy-covariance measurements between 2002 and 2006 showed a mean net ecosystem carbon loss of 0.25 ± 0.04 μmol m-2 s-1, with a mean respiration rate of 8.60 ± 0.11 μmol m-2 s-1 at our site. We found that lost nocturnal flux can potentially introduce significant bias into these results. We develop robust approaches to correct for these biases, showing that, where appropriate, a site-specific u* threshold can be used to avoid systematic bias in estimates of carbon exchange. Because of the presence of gaps in the data and the day-night asymmetry between storage and turbulence, inclusion of canopy storage is essential to accurate assessments of NEE. We found that short-term measurements of storage may be adequate to accurately model storage for use in obtaining ecosystem carbon balance, at sites where storage is not routinely measured. The analytical framework utilized in this study can be applied to other Eddy-covariance sites to help correct and validate measurements of the carbon cycle and its components. © 2008 Elsevier B.V. All rights reserved.

Please use this identifier to cite or link to this item:

http://hdl.handle.net/10453/14689