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Towards operational remote sensing of forest carbon balance across Northern Europe

Olofsson, Pontus LU ; Lagergren, Fredrik LU ; Lindroth, Anders LU ; Lindström, Johan LU ; Klemedtsson, Leif; Kutsch, Werner and Eklundh, Lars LU (2008) In Biogeosciences 5(3). p.817-832
Abstract
Monthly averages of ecosystem respiration (ER), gross primary production (GPP) and net ecosystem exchange (NEE) over Scandinavian forest sites were estimated using regression models driven by air temperature (AT), absorbed photosynthetically active radiation (APAR) and vegetation indices. The models were constructed and evaluated using satellite data from Terra/MODIS and measured data collected at seven flux tower sites in northern Europe. Data used for model construction was excluded from the evaluation. Relationships between ground measured variables and the independent variables were investigated.



It was found that the enhanced vegetation index (EVI) at 250 m resolution was highly noisy for the coniferous sites, and... (More)
Monthly averages of ecosystem respiration (ER), gross primary production (GPP) and net ecosystem exchange (NEE) over Scandinavian forest sites were estimated using regression models driven by air temperature (AT), absorbed photosynthetically active radiation (APAR) and vegetation indices. The models were constructed and evaluated using satellite data from Terra/MODIS and measured data collected at seven flux tower sites in northern Europe. Data used for model construction was excluded from the evaluation. Relationships between ground measured variables and the independent variables were investigated.



It was found that the enhanced vegetation index (EVI) at 250 m resolution was highly noisy for the coniferous sites, and hence, 1 km EVI was used for the analysis. Linear relationships between EVI and the biophysical variables were found: correlation coefficients between EVI and GPP, NEE, and AT ranged from 0.90 to 0.79 for the deciduous data, and from 0.85 to 0.67 for the coniferous data. Due to saturation, there were no linear relationships between normalized difference vegetation index (NDVI) and the ground measured parameters found at any site. APAR correlated better with the parameters in question than the vegetation indices. Modeled GPP and ER were in good agreement with measured values, with more than 90% of the variation in measured GPP and ER being explained by the coniferous models. The site-specific respiration rate at 10&deg;C (<i>R</i><sub>10</sub>) was needed for describing the ER variation between sites. Even though monthly NEE was modeled with less accuracy than GPP, 61% and 75% (dec. and con., respectively) of the variation in the measured time series was explained by the model. These results are important for moving towards operational remote sensing of forest carbon balance across Northern Europe. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
MODIS, NPP, carbon balance, respiration, NEE, remote sensing, NDVI
in
Biogeosciences
volume
5
issue
3
pages
817 - 832
publisher
Copernicus Publications
external identifiers
  • wos:000257303400014
  • scopus:44349094860
ISSN
1726-4189
DOI
10.5194/bg-5-817-2008
language
English
LU publication?
yes
id
8a6097d8-10c8-4058-b262-6c2a5b0b8d3b (old id 694566)
alternative location
http://www.biogeosciences.net/5/817/2008/bg-5-817-2008.html
date added to LUP
2007-12-17 10:27:18
date last changed
2017-04-16 03:32:33
@article{8a6097d8-10c8-4058-b262-6c2a5b0b8d3b,
  abstract     = {Monthly averages of ecosystem respiration (ER), gross primary production (GPP) and net ecosystem exchange (NEE) over Scandinavian forest sites were estimated using regression models driven by air temperature (AT), absorbed photosynthetically active radiation (APAR) and vegetation indices. The models were constructed and evaluated using satellite data from Terra/MODIS and measured data collected at seven flux tower sites in northern Europe. Data used for model construction was excluded from the evaluation. Relationships between ground measured variables and the independent variables were investigated.<br/><br>
<br/><br>
It was found that the enhanced vegetation index (EVI) at 250 m resolution was highly noisy for the coniferous sites, and hence, 1 km EVI was used for the analysis. Linear relationships between EVI and the biophysical variables were found: correlation coefficients between EVI and GPP, NEE, and AT ranged from 0.90 to 0.79 for the deciduous data, and from 0.85 to 0.67 for the coniferous data. Due to saturation, there were no linear relationships between normalized difference vegetation index (NDVI) and the ground measured parameters found at any site. APAR correlated better with the parameters in question than the vegetation indices. Modeled GPP and ER were in good agreement with measured values, with more than 90% of the variation in measured GPP and ER being explained by the coniferous models. The site-specific respiration rate at 10&amp;deg;C (&lt;i&gt;R&lt;/i&gt;&lt;sub&gt;10&lt;/sub&gt;) was needed for describing the ER variation between sites. Even though monthly NEE was modeled with less accuracy than GPP, 61% and 75% (dec. and con., respectively) of the variation in the measured time series was explained by the model. These results are important for moving towards operational remote sensing of forest carbon balance across Northern Europe.},
  author       = {Olofsson, Pontus and Lagergren, Fredrik and Lindroth, Anders and Lindström, Johan and Klemedtsson, Leif and Kutsch, Werner and Eklundh, Lars},
  issn         = {1726-4189},
  keyword      = {MODIS,NPP,carbon balance,respiration,NEE,remote sensing,NDVI},
  language     = {eng},
  number       = {3},
  pages        = {817--832},
  publisher    = {Copernicus Publications},
  series       = {Biogeosciences},
  title        = {Towards operational remote sensing of forest carbon balance across Northern Europe},
  url          = {http://dx.doi.org/10.5194/bg-5-817-2008},
  volume       = {5},
  year         = {2008},
}