Relative Species Richness
Models of the relative species richness of trees/shrubs in burnt and
unburnt plots had limited explanatory power (i.e., 5.78%), and model
averaging revealed that the 95% confidence intervals of most parameter
estimates overlapped zero (Table 2). Protection status did, however,
influence relative species richness of trees/shrubs – with species
richness increasing at burnt sites relative to unburnt controls in
unprotected sites, whilst within protected sites species richness was
more similar in burnt and unburnt sites (Table 2; Fig. 2a). Models of
forb relative species richness in burnt and unburnt plots had much
higher explanatory power (i.e., 41.74%) than models for other life
forms (Table 2). Model averaging revealed interactions between biome
type and type of fire. In flooded grasslands and savannahs forb species
richness increased in plots experiencing non-prescribed burns relative
to unburnt controls, with species richness being more similar in burnt
and unburnt controls following prescribed burns (Table 2; Fig. 2b). In
contrast, in moist broadleaved forest prescribed burns increased forb
species richness relative to unburnt controls, whilst non-prescribed
burns resulted in similar species richness in burnt and unburnt controls
(Table 2; Fig. 2). Models of the relative species richness of climbers
in burnt and unburnt sites also had relatively limited explanatory power
(i.e., 5.17%) with model averaging revealing that prescribed burns
resulted in climber richness increasing in burnt plots relative to
unburnt ones, whilst non-prescribed burns resulted in species richness
declining in burnt sites relative to unburnt controls (Table 2; Fig.
2c). The best model of graminoid relative species richness had a higher
AICc (88.90) than that of the null model which lacked predictors (AICc
86.97).
Table 2: Results from model averaging across multiple
regression models of relative species richness in burnt sites relative
to control (unburnt) sites for trees/shrubs, forbs, and climbers.
Results for graminoids are not included as no model had a lower AICc
than the null model (i.e., one that lacked predictors). Parameter
estimates are provided with 95% confidence intervals in brackets. FGS
(Flooded Grasslands and Savannas); TSCF (Tropical and Sub-tropical
Coniferous Forests); TSDBF (Tropical and Sub-tropical Dry Broadleaf
Forests); TSGSS (Tropical and Sub-tropical Grasslands, Shrublands and
Savannas); and TSMBF (Tropical and Sub-tropical Moist Broadleaf
Forests).