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Aaron C. Greenville, Glenda M. Wardle and Chris R. DickmanDesert Ecology Research Group
School of Biological SciencesUniversity of Sydney
Extreme climatic events drive mammal irruptions: 100-year trends in desert rainfall
and temperature
Extreme climatic events
Current
Climate parameter
Future
Extreme climate: spatial scale
IPCC (2007)
CSIRO & BOM (2012)
Global
Regional
Local
Aims
• To determine if extreme climate events have changed at similar rates to median events over local and regional scales.
• Determine if the frequency of large rainfall events increased.
• Are extreme climate events important for drive small mammal populations?
Methods: study region
• 11 weather stations for annual rainfall.• 4 weather stations for annual min and max
temperatures.• Small mammal trapping from Ethabuka Reserve.
Methods: climate
• Quantile regressions at 5,10, 50, 90 and 95th
• Poisson GLMM
Min Temp
1890 1920 1950 1980 2010
10
11
12
13
14
15
Alice Springs
Year
An
nu
al
min
imu
m t
emp
era
ture
(°
C)
1890 1920 1950 1980 2010
14
15
16
17
18
19
Boulia
Year
An
nu
al
min
imu
m t
emp
era
ture
(°
C)
1938 1962 1986 2010
13.5
14.0
14.5
15.0
15.5
16.0
Oodnadatta
Year
An
nu
al
min
imu
m t
emp
era
ture
(°
C)
1965 1980 1995 2010
14
15
16
17
Birdsville
Year
An
nu
al
min
imu
m t
emp
era
ture
(°
C)
P < 0.05
Max Temp
1885 1910 1935 1960 1985 2010
27
28
29
30
Alice Springs
Year
An
nu
al
ma
xim
um
tem
per
atu
re (
° C
)
1890 1910 1930 1950 1970 1990 2010
30
31
32
33
34
Boulia
Year
An
nu
al
ma
xim
um
tem
per
atu
re (
° C
)
1960 1970 1980 1990 2000 2010
29
30
31
32
Birdsville
Year
An
nu
al
ma
xim
um
tem
per
atu
re (
° C
)
1940 1950 1960 1970 1980 1990 2000 2010
27
28
29
30
31
Oodnadatta
Year
An
nu
al
ma
xim
um
tem
per
atu
re (
° C
)
P < 0.05
Rainfall
P < 0.05
1930 1950 1970 1990 2010
50
180
310
440
570
700
Bedourie
Year
An
nu
al
Ra
infa
ll (
mm
)
1890 1920 1950 1980 2010
50
180
310
440
570
700
Glenormiston
Year
An
nu
al
Ra
infa
ll (
mm
)
1905 1940 1975 2010
100
200
300
400
Oodnadatta
Year
An
nu
al
Ra
infa
ll (
mm
)
1870 1905 1940 1975 2010
200
400
600
800
Alice Springs
Year
An
nu
al
Ra
infa
ll (
mm
)
Extreme high eventsExtreme low eventsMedian events
Rainfall
Results: climate
• Decrease in years between extreme rainfall events (>95th quantile).
• GLMM estimate: -0.54, SE = 0.21, z value = -2.54, P = 0.01.
Methods: small mammals
• 22 years live-trapping data:
– rodents and dasyurids.
• Threshold relationship.
• Piecewise regression.
Results: small mammals
Rodents
Dasyurids
Summary• Extreme and median temperatures have
increased at both spatial scales.
• Magnitude of extreme rainfall events have increased, droughts getting drier, but variable across the region.
• Increased frequency of large rainfall events.
• Populations driven by extreme climate events.
Implications
• Increased wildfire.
• Establishment of introduced
species.
• Indirect effects and new
interactions.
• For more: Ecology and Evolution 2012; 2(11): 2645–2658.
Acknowledgements• Bobby Tamayo and the DERG team.• All our volunteers.• Bush Heritage Australia.• Bedourie Hotel.• ARC and APA.
Volunteer info at:http://sydney.edu.au/science/biology/sites/dickmanlab/index.shtml
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