Fire in Chile - Fire in Mediterranean Ecosystems - page 160

1978 ; Montenegro et al. 1983 ). The vigor of resprouting is typically high in woody
shrub and arborescent species such as Lithraea caustica , Kageneckia oblonga , Quil-
laja saponaria , Azara dentata and Cryptocarya alba , but is relatively weak in colon-
izing and semi-woody species such as Baccharis linearis , Muehlenbeckia hastulata
and Colliguaya odorifera (Segura et al. 1998 ).
All Chilean matorral shrubs establish seedlings in the absence of fire (Fuentes
et al. 1984 , 1989 , 1994 ; Fuentes & Espinoza 1986 ). This fire-independent
recruitment syndrome is typically associated with particular fruit characteristics
that enhance dispersal (see Chapter 9), and for species with this syndrome (i.e.
obligate resprouters) there are marked similarities between Chile and California
(Hoffmann et al. 1989 ). In Chile, most woody shrubs have animal-dispersed
propagules, and isolated shrubs provide suitable perching sites (Jime´ nez &
Armesto 1992 ). This dispersal pattern may account for the preponderance of
seedling recruitment being associated with shrub clumps (Fuentes et al. 1984 ),
although factors during recruitment also appear to play a role (Holmgren et al.
2000b ).
A small number of matorral shrubs accumulate soil seedbanks between fires,
and may also produce a small pulse of seedling recruitment in the first growing
season after fire. However, these are from hard-coated seeds in families such as the
Fabaceae and Rhamnaceae, and they germinate under a range of disturbance
conditions. Examples of shrub species that may establish abundant seedlings after
low-intensity fires are Acacia caven , Trevoa trinervis , and Muehlenbeckia hastulata
(Mun˜ oz and Fuentes 1989 ; Fuentes et al. 1994 ; Segura et al. 1998 ). Canopy storage
of dormant seeds in serotinous cones or fruits, as occurs in the South African and
Australian MTC regions, is not present in any of the Chilean matorral species.
Although fires promote the germination and establishment of some herbaceous
species in matorral (S. Keeley & Johnson 1977 ;A ´ vila et al. 1981 ), most seeds in
matorral soils are killed by the heat of a fire (Mun˜ oz & Fuentes 1989 ; Segura et al.
1998 ). The widespread annual flora of open matorral stands largely consists of
generalist species, as well as an abundance of non-native European annual grasses
and forbs, with transient seedbanks (Figueroa & Jaksic 2004 ). Several studies have
suggested that anthropogenic fires in central Chile may promote the invasion of
alien plants with fire-adaptive traits not present in the native flora (Mun˜ oz &
Fuentes 1989 ; Segura et al. 1998 ; Holmgren et al. 2000a , 2000b ; Figueroa et al.
2009 ;G´ mez-Gonza´ lez & Cavieres 2009 ). Field studies in matorral have found
that fire has little or no influence on the composition of herb floras and herb
abundance (Holmgren et al. 2000a ), although fire appears to promote the invasion
of alien annual species under some conditions (A ´ vila et al. 1988 ). Other studies
have shown that high-intensity fires negatively affect the seedling emergence of
both native and alien species, but more strongly so in native species. Low-intensity
fires do not significantly affect the emergence of native herbs but did lead
to increased alien species richness (Go´ mez-Gonza´ lez & Cavieres 2009 ). Fire-
following annuals with dormancy broken by chemical cues from ash have not
been recorded from Chile.