Agriculture Reference
In-Depth Information
7
Fire in the Cape Region
of South Africa
South Africa's mediterranean-type climate (MTC) region is the smallest of the
five MTC regions, centered in the southwestern corner of the Western Cape
Province (
Fig. 7.1
). This Cape region is dominated by fynbos shrublands (see
Fig. 1.6e
) but this fynbos biome continues eastward far outside the MTC. The
Cape region is unusual in that shrublands dominate under climate regimes that
also support forests. Entire landscapes can support alternative ecosystem states.
Even the semi-arid areas can support entirely different vegetation: fire-prone
shrublands or fire-resistant broadleaf thickets. Perhaps more than any other
MTC region, fire plays a central role in determining major vegetation patterns
of winter rainfall regions of South Africa. Soils are also thought to be of major
importance since much of the Cape's MTC region is on nutrient-poor sandy
soils (see
Fig. 1.5
). A complex interplay between soils, fire and climate and, in the
east, large mammal herbivory, determines boundaries of major biomes. The Cape
Floristic Region is extremely rich in species with very high levels of endemism
(Linder
2003
). It is the world's richest temperate flora and is largely restricted
to fire-prone ecosystems (Cowling
et al.
1996
; Linder
2003
). So, contrary to
the widely held popular belief that fires are an anthropogenic disturbance
(e.g. Pillans
1924
; Axelrod
1980
), or merely incidental to this formation (Hopper
2009
), a rich endemic flora has evolved in the Cape whose members are
overwhelmingly fire dependent,
implying a long history of natural fires as a
selective force.
Major Vegetation Patterns
This chapter discusses fire regimes in the Cape region, what little is known of their
determinants, and how they influence major vegetation patterns in the region.
Though a large number of studies have explored plant responses to fire (reviewed
by Bond
1997
; Cowling
et al.
1997a
), these are heavily biased toward fynbos
shrublands, the dominant vegetation cover of the region (
Fig. 7.2
). Fire responses
of species belonging to other vegetation types are poorly known. Yet the existence
of these other vegetation types is one of the central conundrums of the Cape
region. It implies failure of climate alone to explain apparent convergence with
