Agriculture Reference
In-Depth Information
(a)
(b)
Fig. 1.7
Forests are widespread in some MTC regions; in particular: (a)
Pinus
-dominated
conifer forest in California, and (b)
Eucalyptus
-dominated broadleaf forest in southern
Australia. These forest types are widespread far outside the MTC on both continents. Similar
conifer-dominated forests occur in the Mediterranean Basin and broadleaf and conifer forests
in southern Chile, but such forests are largely lacking in the South African Cape region
.
(Photos by Jon Keeley.)
A central concept that ties together the five MTC regions is the hypothesis
that these ecosystems exhibit a remarkable degree of evolutionary convergence
in the structure and function of many taxa. The idea originated with the
nineteenth-century geographers and botanists Grisebach (
1872
) and Schimper
(
1903
). They recognized that disparate regions of the world possessed similar
sclerophyllous woodlands, and that the greatest centers of evergreen sclerophyl-
lous leaf development were in regions of MTC. Similarities between these
regions were evident at the community scale as all comprised vegetation with
similar growth forms, including a high preponderance of multistemmed shrubby
phanerophytes (see Raunkiaer growth form entry in
Box 1.2
) and geophytes.
Despite these remarkable similarities, MTC regions were floristically very
different and such observations formed the basis for one of the classical
examples of evolutionary convergence. This concept provided an important
opportunity for testing ideas of adaptation in intensive comparative studies of
MTC ecosystems beginning in the early 1970s by Mooney and colleagues
(di Castri & Mooney
1973
; Mooney
1977a
). This International Biological
