Agriculture Reference
In-Depth Information
Landscape conditions
Local conditions
Community
heterogeneity
Distance
from
coast
0.95
HETERO-
GENEITY
r
2
= 0.53
1.0
0.40
0.38/0.32
1.0
LANDSCAPE
POSITION
RICHNESS
spp./plot
0.27/0.20
0.46
LOCAL
ABIOTIC
CONDITIONS
0.26/0.18
- 0.28
Abiotic
optimum
0.31/0.25
1.0
- 0.46
0.49
STAND
AGE
FIRE
SEVERITY
PLANT
COVER
1.0
1.0
0.95
Fire
index 1
Total
cover
Age
Fig. 11.6
Structural equation model of direct and indirect effects on postfire diversity in
chaparral 5 years after fire (Grace & Keeley
2006
). Circles signify latent variables used to
represent theoretical concepts of interest, while rectangles represent observed variables that
serve as indicators of latent variables. Numbers associated with paths from latent to observed
variables represent loadings, while numbers associated with paths between latent variables
represent path coefficients.
different fire histories and this can have profound impacts on landscape patterns
of plant and animal diversity (Fox
1983
; Ferrenberg
et al.
2006
; Knapp
et al.
2007
).
Regional diversity of MTC landscapes is among the highest recorded globally
(Cowling
et al.
1996
; Myers
et al.
2000
), and since these are also among the most
fire-prone systems in the world, fire should be given some consideration for its
contribution to regional diversity. This would seem to be borne out in the fact that
many taxa within these regions are not just resilient to fire but also dependent on
fire and owe their origin to fire-selected traits.
Fire can also affect regional species diversity through localized selection of
endemics that are restricted by substrate and/or climate. Where this is most