7th Workshop on Forest Fire Management - EARSeL, European ...

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I - PRE-FIRE PLANNING AND MANAGEMENT
al., 1996). The simulation of realistic fire disturbance regimes with biophysical
and biogeochemical models is a prerequisite for reducing the
uncertainty of the African carbon cycle, and the feedbacks associated with
this cycle and the global climate system.
2 - Materials and methods
2.1 - Model description
The model applied in this study is JULES (Joint UK Land Environment
Simulator), which is the community version of the UK Met Office’s MOSES
land-surface model. JULES is described in more detail by Cox et al. (1999),
but in essence was developed for coupling to a GCM, in order to calculate
the surface-to-atmosphere fluxes of heat and water. Each surface gridbox is
represented as mixture of five plant functional types: broadleaf trees,
needleleaf trees, C 3 grasses, C 4 grasses, and shrubs; and four non-vegetation
types: urban, inland water, bare soil and ice.
2.2 - Experimental setup
For this study, JULES was run from 1982 to 2003 at 0.5° x 0.5° spatial resolution
for IGBP land classes representing savannas and grasslands for
southern hemisphere continental Africa. Meteorological input data were
taken from 6-hourly NCEP reanalysis (Kalnay et al., 1996) and TRMM precipitation
(Kummerow et al., 1998) datasets. The selected IGBP land classes
were mapped onto the nine JULES surface tiles in accordance with
Dunderdale et al. (1999), and soil parameters were derived from the ISLSCP
II soil data set (Global Soil Data Task, 2000). Prior to the main run the
model was spun-up for a period exceeding 200 years, to enable the soil
temperature and soil moisture to reach a state of equilibrium.
An archive of FMC field measurements from four sites within Kruger National
Park (KNP), South Africa covering the years 1982 to 2003 were used to calibrate
and validate the model. These measurements were obtained by comparing
the sample weights before and after oven-drying. Measurements
acquired from Skukuza and Pretoriuskop sites were used for calibration,
with measurements from from Satara and Mopani sites used for validation.
3 - Results and discussion
For calibration of the model from measurements obtained from Skukuza and
Pretoriuskop sites for 1982 to 2003 (Fig. 1, left), the determination coefficient
(r 2 ) produced from the nonlinear multiple regression equation was
0.568 (p < 0.001):