Agriculture Reference
In-Depth Information
20
E
30
E
Cape Town
Port Elizabeth
Legend
INDIAN OCEAN
Mediterranean-type climate
Mediterranean-type veg
0
125
250
500
750
1,000
Kilometers
30
E
Fig. 7.1
Distribution of the mediterranean-type climate (MTC) in the Western Cape Province
of South Africa (dark shading) and shrublands dominated by mediterranean-type vegetation
(MTV) outside the MTC region (hatched).
other MTC regions (
Chapter 1
). For example, low shrublands would be expected
in deserts replaced, as rainfall progressively increases, by taller shrublands, wood-
lands and then forests. But this is clearly not the case in the Cape region. The
dominant fynbos vegetation shows very little variation in aboveground biomass
from arid desert fringes (mean annual precipitation
250 mm) to rain-drenched
high-altitude heathlands (> 3000 mm) (
Fig. 7.3
). Yet across the entire rainfall
gradient fynbos co-occurs with alternative ecosystems with much greater woody
biomass. These broadleaf thickets and forests have an entirely different floristic
and functional composition and often are restricted to isolated fire-protected
refugia (
Fig. 7.2
; Taylor
1978
; Kruger
1979
; Cowling
et al.
2005
; Rebelo
et al.
2006
). The implication is that apparent convergence of shrubby fynbos growth
forms with other MTC plant communities cannot be understood in terms of
climate alone and that one needs to think in terms of the climate, fire, geology
filter (see
Fig. 1.4
).
∼
