Esa12 extreme climatic events drive mammal irruptions

222 views

Published on

Published in: Technology, Education
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
222
On SlideShare
0
From Embeds
0
Number of Embeds
4
Actions
Shares
0
Downloads
1
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • Usually talk about means/medians when analysing changes in climate, but extreme climate events, although statistically rare, are important mechanisms for ecosystem functionE.g. Hurricanes/cyclones –forest, cassowary –Long droughts – increased mortality of species extreme rainfall events, like in central Aust over the last couple of years – irruption in animal populationsAlso predicted to increase in mag and freq. from climate change making them important to mechanisms to understand for ecologists.
  • Also important for ecologists to understand is how extreme climate events will manifest themselves on diff spatial scales-increases in temp predicted ofr global scales but how manifest on regional or local scales maybe quite different.Important for predicting the affect of climate change on biodiversity
  • magn of extreme climate events have changed over time for central Aust.Changed at similar rates to the medianChanged consistent across different spatial scalesLocal scale = weather stationRegional = simpson desert
  • Simpson desert b/w 200-400 mm isopleths170 000 km2 areaRecords ~100 years from all avail stations were usedCaptures of small mammal from Ethabuka reserve
  • Quantile regression for if magnitude has changedGLMM for if the years b/w extreme rainfall events has decreased. 95thWeather stations as random, with slope an intercept allowed to vary to account for variation b/w weather stations.
  • Year on x-axis and min temp on y-axis. Introduce quantilesSign quantiles are in redMin temps rising in both the lower extremes, median and upper extremes, except AliceNo diff b/w the rate of increase of extremes or median range
  • No diff in rate of change b/w median and extremes.
  • Won’t show you all 11 graphs, but here is a respresentive set.Glen and bed 95th > than median
  • Extreme high rainfall events all increasingExtreme low all decreasingMedian increasing4 weather stations had no sign change
  • Across simpson desert
  • Restate aimSmall mammals split by rodents and dasy as they have diff responses to rainfall. E.g. Spin hop mouse, lesser hairy footed dunnartAnnual Rainfall from year before. Allow for lag from breeding and migration.Measured onsite and missing values filled from nearest station.Thresholds: no change in pop unless an extreme rainfall event occursPiecewise reg fits two linear lines, where they meet is the break point and id the threshold. All analyse performed in R
  • ~400 mm represents an extreme rainfall event ~95th for ethabuka
  • Extreme and median annual min and max temps have increased at both local and regional scales. Changes in global temp may manifest themselves in smaller scales in the same manner.No diff in rate of increase b/w median and extreme eventsRainfall in extremely wet years is increasing at greater rates than the median. Highlighting the importance of investigating extreme events.
  • Implications from this climate change- Wildfire driven by 90th quantile events as seen last summer.Intro predators and other feral species become established in the drier areas of central auste.g. House mice, rabbits and foxes.Dasy not driven by rainfall directly – if wildfires increase and introduced predator populations increase they could be indirectly neg affected.Wildfires reduce cover and increase predation risk.Lastly -Novel interactions driven by the changing climate. Taking all these things together, changes in climate and extreme climate events will lead to significant changes to the ecology of central Aust.
  • Esa12 extreme climatic events drive mammal irruptions

    1. 1. Extreme climatic events drive mammal irruptions: 100-year trends in desert rainfall and temperature Aaron C. Greenville, Glenda M. Wardle and Chris R. Dickman Desert Ecology Research Group School of Biological Sciences University of Sydney
    2. 2. Extreme climatic events Current Future Climate parameter
    3. 3. Extreme climate: spatial scale CSIRO & BOM (2012) Global Regional Local IPCC (2007)
    4. 4. 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?
    5. 5. Methods: study region • 11 weather stations for annual rainfall. • 4 weather stations for annual min and max temperatures. • Small mammal trapping from Ethabuka Reserve.
    6. 6. Methods: climate • Quantile regressions at 5,10, 50, 90 and 95th • Poisson GLMM
    7. 7. 1938 1950 1962 Year 1980 1986 2010 17 1920 16 1890 15 11 12 13 14 15 2010 14 15 16 17 18 19 Annual minimum temperature (° C) 10 Annual minimum temperature (° C) Alice Springs Min Temp 14 Annual minimum temperature (° C) 13.5 14.0 14.5 15.0 15.5 16.0 Annual minimum temperature (° C) P < 0.05 Boulia 1890 1920 Year Oodnadatta 1965 1950 1980 Year 1980 1995 2010 Year Birdsville 2010
    8. 8. P < 0.05 Max Temp Boulia 1885 1910 1935 1960 1985 34 33 32 31 30 Annual maximum temperature (° C) 30 29 28 27 Annual maximum temperature (° C) Alice Springs 1890 2010 1910 1930 2010 2000 2010 32 31 30 29 Annual maximum temperature (° C) 31 30 29 28 27 Annual maximum temperature (° C) 1990 Birdsville Oodnadatta Year 1970 Year Year 1940 1950 1960 1970 1980 1990 2000 2010 1950 1960 1970 1980 Year 1990
    9. 9. P < 0.05 Rainfall 700 570 440 310 50 180 400 600 Annual Rainfall (mm) 800 Glenormiston 200 Annual Rainfall (mm) Alice Springs 1870 1905 1940 1975 2010 1890 1920 Year 1980 2010 1990 2010 Year Bedourie 570 440 310 180 50 100 200 300 Annual Rainfall (mm) 400 700 Oodnadatta Annual Rainfall (mm) 1950 1905 1940 Year 1975 2010 1930 1950 1970 Year
    10. 10. Rainfall Extreme high events Extreme low events Median events
    11. 11. 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.
    12. 12. Methods: small mammals • 22 years live-trapping data: – rodents and dasyurids. • Threshold relationship. • Piecewise regression.
    13. 13. Results: small mammals Rodents Dasyurids
    14. 14. 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.
    15. 15. Implications • Increased wildfire. • Establishment of introduced species. • Indirect effects and new interactions. • For more: Ecology and Evolution 2012; 2(11): 2645–2658.
    16. 16. 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

    ×