Model Of Forest Carbon Sequestration Incorporating Aerial Wood Radiative Budget

The CHANCE model, simulating CO2, energy and water fluxes in a forest ecosystem, is presented. The components of
the simulated canopy are the leaves, the branches, the trunks and the soil. The first three are divided into sunny and shaded
zones. The model has been calibrated and validated in comparison with measurements performed in the temperate beech
forest of Vielsalm (Belgium). For the reproduction of half-hourly net CO2 fluxes, the quality of the CHANCE results is
comparable to other models (systematic error of 14%—0.51 molm−2 s−1, R2 = 0.79). The differences between simulated
and measured fluxes result essentially from noise in the data, underestimation of the stomatal conductance during very dry days
and heterogeneity of the south, southeast sector (presence of conifer patches). Three sensitivity tests have been performed.
The first one, neglecting the contribution of aerial wood in the radiation budget, doubles the annual carbon sequestration
(Seco). This trend is strengthened in the second test where common radiative and photosynthetic properties are assigned to
leaves and branches. The third test induces a 30% reduction of Seco when the calculation of canopy component temperatures
using the complete energy balance is replaced by the use of air temperature.
© 2004 Elsevier B.V. All rights reserved.