Carbon mass fluxes of forests in Belgium determined with low resolution optical sensors

The primary objective of this paper is to describe the validation of a parametric model (C-Fix) designed to estimate the basic carbon mass fluxes of forests in Belgium. Most validation efforts in the literature are based on point measurements. Since landscapes in Belgium are quite heterogeneous, the spatial up-scaling of a point measurement to the level of a sensor pixel is a crucial issue. Process based models quite often have a large set of input variables, some of them hardly available or not measurable on a regional basis; on the other hand most of the process based models possess a prognostic capacity. The parametric C-Fix model estimates carbon mass fluxes from local, regional to continental scales. It ingests only a modest number of meteorological input variables, including satellite observations. Parametric models do not possess a prognostic capacity, but the spatial up-scaling by the use of remote sensing data is much more straightforward than with process models. In this paper, we describe the validation of C-Fix with eddy covariance NEP (net ecosystem production) measurements and further applied C-Fix for the mapping of the geographical distribution of carbon mass fluxes over the entire Belgian territory, using NOAA-AVHRR (1997) and SPOT4-VGT imagery (April 1998–March 1999). We combine a forest probability map, derived from NOAA data for 1997 with the mapped estimates of Belgian NEP to obtain forest NEP per image pixel. Forest NEP is validated regionally, with measurements of carbon exchange obtained at two Belgian Euroflux eddy covariance tower sites (the Brasschaat, ‘Inslag’ and Vielsalm, ‘Tinseubois' forest sites). A correlation analysis is performed for the estimated forest NEPs at both Euroflux sites and the NEP measured there, assumed to be primarily from forest. Finally, a correlation analysis with a process-based stand scale model (ASPECTS) is performed for the two forest sites, as a cross check on the validation results. Our results demonstrate that a parametric model, like C-Fix, provides a good basis to estimate the evolution and geographical distribution of the main constituents of the carbon budget of terrestrial ecosystems, in this study specifically forest ecosystems at the regional scale (Belgium).

[1]  D. Pury,et al.  Simple scaling of photosynthesis from leaves to canopies without the errors of big‐leaf models , 1997 .

[2]  Eddy-covariance CO2 flux measurements using open- and closed-path CO2 analysers: Corrections for analyser water vapour sensitivity and damping of fluctuations in air sampling tubes , 1991 .

[3]  D. Paslier,et al.  Net Exchange of CO2 in a Mid-Latitude Forest , 1993, Science.

[4]  Frank Veroustraete,et al.  Seasonal variations in leaf area index, leaf chlorophyll, and water content; scaling-up to estimate fAPAR and carbon balance in a multilayer, multispecies temperate forest. , 1999, Tree physiology.

[5]  F. Veroustraete,et al.  Estimation of carbon mass fluxes over Europe using the C-Fix model and Euroflux data , 2002 .

[6]  P. Buringh.  The role of terrestrial vegetation in the global carbon cycle , 2006 .

[7]  M. Aubinet,et al.  Modelling short-term CO2 fluxes and long-term tree growth in temperate forests with ASPECTS , 2001 .

[8]  Frank Veroustraete,et al.  MC-FUME: A new method for compositing individual reflective channels , 2000, IEEE Trans. Geosci. Remote. Sens..

[9]  Tiina Markkanen,et al.  Footprint Analysis For Measurements Over A Heterogeneous Forest , 2000 .

[10]  Gérard Dedieu,et al.  Monitoring seasonal and interannual variations of gross primary productivity, net primary productivity and net ecosystem productivity using a diagnostic model and remotely‐sensed data , 1995 .

[11]  George M. Woodwell,et al.  The role of terrestrial vegetation in the global carbon cycle : measurement by remote sensing , 1985 .

[12]  M. Déqué,et al.  The ARPEGE/IFS atmosphere model: a contribution to the French community climate modelling , 1994 .

[13]  S. Goward,et al.  Evaluating North American net primary productivity with satellite observations , 1987 .

[14]  I. Levin,et al.  Long‐term observations of atmospheric CO2 and carbon isotopes at continental sites in Germany , 1995 .

[15]  F. Veroustraete,et al.  On the use of a simple deciduous forest model for the interpretation of climate change effects at the level of carbon dynamics , 1994 .

[16]  Ranga B. Myneni,et al.  Estimating net ecosystem exchange of carbon using the normalized difference vegetation index and an ecosystem model , 1996 .

[17]  R. Myneni,et al.  On the relationship between FAPAR and NDVI , 1994 .

[18]  A. Verhoef,et al.  A system to measure surface fluxes of momentum, sensible heat, water vapour and carbon dioxide , 1997 .

[19]  Yadvinder Malhi,et al.  The use of eddy covariance to infer the net carbon dioxide uptake of Brazilian rain forest , 1996 .

[20]  K. Mccree.  Test of current definitions of photosynthetically active radiation against leaf photosynthesis data , 1972 .

[21]  Ü. Rannik,et al.  Respiration as the main determinant of carbon balance in European forests , 2000, Nature.

[22]  John Moncrieff,et al.  Eddy-covariance CO2 flux measurements using open- and closed-path CO2 analysers: Corrections for analyser water vapour sensitivity and damping of fluctuations in air sampling tubes , 1990 .

[23]  R. Leuning.  A critical appraisal of a combined stomatal‐photosynthesis model for C3 plants , 1995 .