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- Title
A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies.
- Authors
Andreas AI Ibrom; Paul PGJ Jarvis; Robert RC Clement; Kai KM Morgenstern; Alexander AO Oltchev; Belinda BEM Medlyn; Ying YPW Wang; Lisa LW Wingate; John JBM Moncrieff; Gode GG Gravenhorst
- Abstract
Gross canopy photosynthesis (Pg) can be simulated with canopy models or retrieved from turbulent carbon dioxide (CO2) flux measurements above the forest canopy. We compare the two estimates and illustrate our findings with two case studies. We used the three-dimensional canopy model MAESTRA to simulate Pg of two spruce forests differing in age and structure. Model parameter acquisition and model sensitivity to selected model parameters are described, and modeled results are compared with independent flux estimates. Despite higher photon fluxes at the site, an older German Norway spruce (Picea abies L. (Karst.)) canopy took up 25% less CO2 from the atmosphere than a young Scottish Sitka spruce (Picea sitchensis (Bong.) Carr.) plantation. The average magnitudes of Pg and the differences between the two canopies were satisfactorily represented by the model. The main reasons for the different uptake rates were a slightly smaller quantum yield and lower absorptance of the Norway spruce stand because of a more clumped canopy structure. The model did not represent the scatter in the turbulent CO2 flux densities, which was of the same order of magnitude as the non-photosynthetically-active-radiation-induced biophysical variability in the simulated Pg. Analysis of residuals identified only small systematic differences between the modeled flux estimates and turbulent flux measurements at high vapor pressure saturation deficits. The merits and limitations of comparative analysis for quality evaluation of both methods are discussed. From this analysis, we recommend use of both parameter sets and model structure as a basis for future applications and model development.
- Subjects
PLANT canopies; PHOTOSYNTHESIS; CARBON dioxide; GASES from plants; FORESTS &; forestry
- Publication
Tree Physiology, 2006, Vol 26, Issue 7, p845
- ISSN
0829-318X
- Publication type
Article
- DOI
10.1093/treephys/26.7.845