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Developing an empirical model of stand GPP with the LUE approach: analysis of eddy covariance data at five contrasting conifer sites in Europe
Author(s) -
MÄKELÄ ANNIKKI,
PULKKINEN MINNA,
KOLARI PASI,
LAGERGREN FREDRIK,
BERBIGIER PAUL,
LINDROTH ANDERS,
LOUSTAU DENIS,
NIKINMAA EERO,
VESALA TIMO,
HARI PERTTI
Publication year - 2008
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2007.01463.x
Subject(s) - photosynthetically active radiation , eddy covariance , environmental science , boreal , vapour pressure deficit , atmospheric sciences , primary production , covariance , temperate climate , leaf area index , ecosystem , mathematics , ecology , statistics , photosynthesis , botany , biology , transpiration , geology
This paper develops a statistical model for daily gross primary production (GPP) in boreal and temperate coniferous forests. The model applies the light use efficiency (LUE) approach, which estimates the conversion efficiency of daily absorbed photosynthetically active radiation (APAR) into daily GPP as a product of potential LUE and modifying factors. The latter were derived from daily total APAR and daily mean temperature, vapour pressure deficit (VPD) and soil water content (SWC). Modelling data came from five European eddy covariance measurement towers over 2–8 years. The model was tested against independent data from two AmeriFlux stations. The model with the APAR, temperature and VPD modifiers worked well in almost all the site–year combinations, but the SWC modifier only improved the fit in few cases. Geographical variation was found in the modifiers and potential LUE in site‐specific models. When a model was fitted to pooled data, differences between sites could be explained by potential LUE, leaf area and environmental conditions. The test against the AmeriFlux data corroborated this finding. The potential LUE varied from 1.9 to 3.1 g C MJ −1 , and a weak correlation was found between foliar nitrogen concentration and potential LUE. Some year‐to‐year variation remained which could be captured by neither the pooled nor the site‐specific models.