Agriculture Reference
In-Depth Information
Relative proportion of different functional types
Mediterranean
California
Chile
South Africa
Australia
Obligate
resprouters
+++++
++++
+++++
+
-
Restricting
seedlings to
postfire sites
Postfire
seeders
++
+++
-
+++++
+++++
Resprouting lost
and total reliance
on seeding
Obligate
seeders
+++
++++
-
++++
+++
Fig. 14.2
In the evolution of fire-dependent ecosystems two important transitions are
evident (see
Fig. 9.5
).
Mediterranean-type climate ecosystems differ in the importance of
these modes.
regimes. Future global changes will be best anticipated by confronting the issue of
fire directly and best management practices require that we think about such
systems in terms of climate, fire and geology interactions if we are to anticipate
future global changes and adapt.
Convergence in Fire-prone Mediterranean-type Climate Ecosystems
Convergence theory states that similar environments will select for similar
biotas through a combination of evolutionary adaptation and ecological
sorting. The five MTC regions have long been noted as examples of convergence
in both the dominance of evergreen sclerophyllous-leaved woody plant commu-
nities of mediterranean-type vegetation (MTV) and their highly fire-prone
character. These regions are tied together by their similar seasonal distribution
of cool weather growing season sufficiently mesic to produce sufficient biomass
capable of spreading fires during the hot, dry fire season. However, no two
environments are identical and subtle differences in climate, not so subtle
differences in geology, and substantial differences in phylogeographical histor-
ies, have all contributed to differences in plant traits (
Fig. 14.2
), community
composition and fire regimes. It should be taken as axiomatic that convergence
is to be expected, but since no two environments are identical the question
becomes, “which environmental factors have played the greatest role in driving
non-convergences?”
