Canadian Forest Service Publications

Sensitivity tests of the integrated biosphere simulator to soil and vegetation characteristics in a pacific coastal coniferous forest. 2002. El Maayar, M.; Price, D.T.; Black, T.A.; Humphreys, E.R.; Jork, E.-M. Atmosphere-Ocean 40(3): 313-332.

Year: 2002

Issued by: Northern Forestry Centre

Catalog ID: 20725

Language: English

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Abstract

Testing and sensitivity analysis of the Integrated BIosphere Simulator (IBIS) were performed for a range of vegetation and soil variables at a temperate coniferous forest site on eastern Vancouver Island, British Columbia, Canada. Vegetation structure and species composition, as well as seasonal changes in vegetation cover fraction and leaf area index, were imposed based on observed data. Simulated fluxes of sensible and latent heat, soil heat and net carbon exchange, and related estimates of soil temperature, soil moisture, and abiotic decomposition, were first compared to a complete year (1998) of half-hourly observed data. The model reproduced observed daily, seasonal and yearly fluxes reasonably well, and was particularly successful in estimating the magnitude of net annual carbon uptake. Because of the high spatial variability in soil moisture content, however, it was difficult to obtain a complete assessment of model performance. Soil texture classification was found to have important effects on all fluxes, and particularly on estimates of soil decomposition, raising concerns about the effects of using spatially aggregated soils data for driving regional and global simulations. Simulation of net ecosystem exchange was also found to be highly sensitive to the value selected for canopy fractional cover and maximum carboxylase activity, Vmax, which suggests that environmental factors, such as limited nutrient availability and changes in vegetation type, will have important impacts on predictions of productivity and carbon budget.