Fire and Wildlife in the Mallee - Eyre Peninsula Natural Resources ...

How old is mallee
vegetation
Knowing the amount and location of
vegetation of different age-classes is valuable
for fire management. Satellite imagery is
useful, but such images are available only
from 1972 onwards.
We developed and validated a technique for
ageing the vegetation based on the average
diameter of mallee eucalypt stems at a site.
These results showed that many sites are
much older than expected, up to 160 years
or more!
This figure shows the estimated percentage
of mallee vegetation in different age-classes.
a) Age classes based on satellite mapping of
fires; all vegetation burned before 1972 is
grouped (orange). b) Greater understanding
of the spread of age-classes based on
estimating age from stem diameters.
60
Percentage
50
40
30
20
10
0
30
20
10
0
35+
30-34
20-29
10-19
0-9
Species respond differently to time since fire
Different species show different responses to changes in the vegetation after fire. For example: a) Chestnut-rumped Thornbill is more likely to be
detected in early stages of regrowth; b) White-eared Honeyeater peaks in occurrence in the mid-successional stage around 40 years post-fire;
and c) Yellow-plumed Honeyeater is most strongly associated with older tree-mallee vegetation (40-100 yrs post-fire).
35-39
80-89
70-89
60-69
50-59
40-49
35-39
30-34
20-29
10-19
0-9
Percentage
80-89
70-89
60-69
50-59
40-49
Years since fire
Years since fire
160-169
150-159
140-149
130-139
120-129
110-119
100-109
90-99
160-169
150-159
140-149
130-139
120-129
110-119
100-109
90-99
a
170-179
b
170-179
...9 years ...43 years ...95 years
Probability of Occurrence a
1.0
Chestnut-rumped Thornbill
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 20 40 60 80 100
Probability of Occurrence b
1.0
White-eared Honeyeater
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 20 40 60 80 100
Probability of Occurrence c
1.0
Yellow-plumed Honeyeater
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 20 40 60 80 100
Years since fire
Communities
change in composition
after fire
Reptile communities, for example, change in
composition following fire. Soil-dwellers, such
as those that use burrows (dark grey shading)
are common in the early stages following fire.
Species that use spinifex (light grey) are most
common in mid-stages (19-50 years), while
the numbers of litter-dwellers (orange shading)
increased with increasing time since fire.
25
20
15
10
5
0
< 1yr
Years since fire
Mean captures per site
Soil-dwellers
Spinifex-dwellers
Litter-dwellers
2-11 yrs 19-50 yrs > 50 yrs
Years since fire
Years since fire