Agriculture Reference
In-Depth Information
Box 7.1 (
cont.
)
Caption for Fig. B7.1.2 (cont.) species and the genera that lack proteoid roots. Scale bar
represents 10 Ma. The different sections of the tree marked by dotted lines refer to
subfamilies (from top to bottom: Symphionematoideae, Proteoideae, Grevilleoideae,
Persoonioideae and Bellendenoideae; Weston & Barker
2006
). The genus
Banksia
sensu
stricto is paraphyletic and so here it includes
Dryandra
(Mast et al.
2005
; Mast and Thiele
2007
). Some genera of Australasia distribution also reach southeast Asia (e.g.
Helicia,
Macadamia).
Most African genera are confined to the Cape region.
Lomatia
and
Orites
are native to both Australia and South America, but are more species rich in Australia. Genera
native to South America are not generally found in MTC ecosystems.
been reported in a few species such as
Lomatia silaifolia
(Denham & Whelan
2000
)and
Telopea speciosissima
(Pyke & Patton
1983
;Bradstock
1995
).
Another fire-adaptive trait is resprouting, which is also widespread in the
family, including many species with lignotubers (see
Table 3.2
).
(
Cliffortia
), Cupressaceae, and even a strange monotypic genus in the Anacardia-
ceae,
Laurophyllus capensis
. Unlike serotinous cones in some conifers that remain
closed with viable seeds for decades, serotiny in most fynbos taxa is relatively
weak, with seeds typically being held for only a few years and then being released
from old fruits even in the absence of fire (Midgley & Enright
2000
). However,
successful recruitment between fires is very rare. Serotiny has not been recorded in
South African savannas, even where
Protea
spp. form the dominant woody plants.
Thus, it is not a fire adaptation
per se
but an adaptive response to a particular fire
regime characterized by crown fires that recur on the order of decades in fynbos
(see
Chapter 3
).
Persistence
There are several ways in which plant species survive fires, either by resprouting
vegetatively or by seedling recruitment. Many fynbos shrubs resprout after fire
and most have seedling recruitment after fire as well and are termed facultative
seeders. A significant number of these resprout from specialized lignotubers (see
Fig. 3.1
and
Table 3.2
).
In contrast, many shrubs do not survive fire and are known as non-resprouters
or
obligate seeders
since their ability to persist on burned sites is entirely due to
seedling recruitment from dormant seedbanks (see
Table 3.4
). A few taller pro-
teoids are usually obligate seeders, but may survive fire if the apical buds are not
damaged (e.g.
Leucospermum conocarpodendron
,
Mimetes fimbriifolius
,
Leucaden-
dron argenteum
). Such species have thicker bark then most other fynbos species,
suggesting adaptation to a somewhat different fire regime. Many plants are only
top killed by fire and belowground parts survive and resprout from vegetative
