Agriculture Reference
In-Depth Information
350
500 000
Number of fires
Area
450 000
300
400 000
250
350 000
300 000
200
250 000
150
200 000
150 000
100
100 000
50
50 000
0
0
123456789 0 1 2
Month
Fig. 7.5 Number of fires and area burned in protected areas across the Cape region. Data
ex Cape Nature and includes montane and lowland fynbos (total area 1 100 000 ha, total
n ¼ 1969 fires, data shown from 1927 to 2006) .
spread ranging from 0.04 to 0.89 m s 1 (van Wilgen et al. 1985 ). However this
range of values does not include fires burning under extreme conditions when fire
intensity is likely to be considerably greater and when large fires are more likely to
occur. Comparison of fynbos fuel loads with other MTC ecosystems (see Table
2.1 ) shows they are higher than Australian heathlands and comparable to younger
stands of Mediterranean Basin matorral and California chaparral.
Postfire Responses
Natural History of Fire Responses
Reproduction
One of the most striking features of a postfire stand of fynbos is the abundance of
seedlings contrasting with unburned stands where there are usually none. Curi-
ously, the phenomenon was not recognized by botanists early in the twentieth
century who argued forcefully for fire suppression (e.g. Pillans 1924 ). Though no
one has counted them all, it seems probable that > 90% of the
6200 plant
species of the fynbos biome recruit seedlings in the first year or two after fire (Le
Maitre & Midgley 1992 ; Cowling et al. 1997a ). Fire-stimulated recruitment is
strong evidence for the importance of fire in plant life histories.
Fire-stimulated recruitment implies the presence of persistent propagules in
which the population locally persists in propagule form after 100% scorch by
fires (Pausas et al. 2004b ). Propagules that survive fire must have fire-stimulated
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