Results |
| The validation of the length of
fire season as well as the fractional area burnt for different ecosystems
was relatively difficult due to limited available observations. This was
not the case for fire return intervals (FRI) described for a wide range of
ecosystems. Thus we converted the fractional area burnt into FRI (being the
reciprocal of the fractional area burnt following the approach of Johnson
& Gutsell (1994)).
The simulation results of the historical FRI
(Fig. 6) confirm the validity of the fire module for a wide range of vegetation
types as the comparison with observations shows (e.g. Mooney et al. 1981;
Goldammer 1990; Goldammer and Furyaev 1996; Whelan 1995; Moreno 1998). Major
geographical gradients are captured by the model, e.g. the bimodal moisture
gradient on the African continent from the Sahara towards the tropical rainforest,
or the temperature gradient in North America, where the south-wards rise
in summer temperature lengthens the fire season, seen in the FRI.
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