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What can history tell us about our ability to
influence the condition of natural resources?

                             ...
What can history tell us about our
ability to influence the condition
      of natural resources?

              Ted Lefro...
Water quality in Tasmanian rivers and estuaries
 Oral history, sediment
                                                  ...
Little Swanport

                      1948
*                     1967

                      1973
                      2...
Sediment cores, air photos, historical records

                     C/N ratios, seagrass fragments, biogenic Si,
        ...
Duck, Montagu, Black & Detention
            Rivers



           *
Duck River
     Oral history, air photos, sediment dating

Black River, Detention River




       Cobble bottom

        ...
Water quality data & space-for-time
            experiment
                 AusRivAs dataset 1999 & 2006
                 ...
Substituting space for time
                   Blue - grazing
                   Hatched - cropping
                   Gre...
Substituting space for time


                  Threshold 55%



                   flow    light  temp

            te...
Detecting recovery
The Pet River




      *
The Pet River
 16 km2 catchment
 5-25% of sub-catchments treated
 12 sub-catchments monitored for 7 years
 No detectab...
Vegetation change 1946-2006
                                           1946



                                           ...
Summary 1
1. Multiple lines of evidence
  – Sediment cores
  – Space-for-time experiments
  – Air photo analysis

  – Hist...
Summary 2
2. In combination, they can be used to identify
  –   Biotic cycles
  –   Large infrequent events
  –   Human di...
Acknowledgements




Estuarine research – John Gibson, Barry Gallagher, Jeff Ross and Christine Crawford
Fresh water – Nel...
The Environment
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What can history tell us about our ability to influence the condition of natural resources?

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Presented by Ted Lefroy as part of the 2009 Place and Purpose Symposium run by the Landscape Science Cluster

Published in: Education, Technology
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Transcript of "What can history tell us about our ability to influence the condition of natural resources?"

  1. 1. What can history tell us about our ability to influence the condition of natural resources? Ted Lefroy
  2. 2. What can history tell us about our ability to influence the condition of natural resources? Ted Lefroy University of Tasmania
  3. 3. Water quality in Tasmanian rivers and estuaries Oral history, sediment Water quality data cores Response to intervention Large infrequent events 1. Sediment cores 2. Space-for-time exp. ** 3. Air photo analysis Historic WQ data, space for time exp. Disturbance thresholds for 4. WQ/veg condition data Tasmanian rivers * 5. Historical records 6. Oral history Sediment cores, air photos, historical records Biotic cycles and Large infrequent events
  4. 4. Little Swanport 1948 * 1967 1973 2003
  5. 5. Sediment cores, air photos, historical records C/N ratios, seagrass fragments, biogenic Si, isotopes, sand, tsunamite, ash Epiphyte growth Epiphyte crash Seagrass decline Seagrass recovery Catastrophic seagrass decline Seagrass recovery Flood or tsunami Epiphyte crash Seagrass recovery Catastrophic seagrass declinedecline Catastrophic seagrass Anthropogenic Flood or tsunami ? Seagrass recovery 1. Biotic cycles * 2. Large infrequent events 3. Human influence
  6. 6. Duck, Montagu, Black & Detention Rivers *
  7. 7. Duck River Oral history, air photos, sediment dating Black River, Detention River Cobble bottom Sediment dating Oral history Mud banks Duck River, Montagu River
  8. 8. Water quality data & space-for-time experiment AusRivAs dataset 1999 & 2006 781 sampling events Water quality, Biota, Geomorphology Habitat 100 90 80 70 60 50 Threshold: > 42% grazing 40 30 20 10 0 0 0.5
  9. 9. Substituting space for time Blue - grazing Hatched - cropping Green - conservation Red - forestry
  10. 10. Substituting space for time Threshold 55%  flow  light  temp terrestrial carbon  algal dominated
  11. 11. Detecting recovery The Pet River *
  12. 12. The Pet River  16 km2 catchment  5-25% of sub-catchments treated  12 sub-catchments monitored for 7 years  No detectable change in N or P
  13. 13. Vegetation change 1946-2006 1946 2006 % Canopy cover ? Large Infrequent Events: Gold, Fire Slow drivers: rabbits, sheep, Landcare, wool prices, tree change 1800 1870 1940 2010 Regeneration = 2 x Revegetation Private investment ~ 2 x Public
  14. 14. Summary 1 1. Multiple lines of evidence – Sediment cores – Space-for-time experiments – Air photo analysis – Historic WQ/veg condition data – Oral history – Historical records
  15. 15. Summary 2 2. In combination, they can be used to identify – Biotic cycles – Large infrequent events – Human disturbance – Recovery in vegetation extent 3. ….but its more challenging to – Document recovery in water quality – Document change in vegetation condition
  16. 16. Acknowledgements Estuarine research – John Gibson, Barry Gallagher, Jeff Ross and Christine Crawford Fresh water – Nelli Horrigan, Reg Majierowski, Steve Read and Peter Davies Riparian – Shane Broad, Bill Cotching and Ross Corkery Vegetation change – Garreth Kyle, Dave Duncan, Libby Rumpf and Graeme Newell www.landscapelogic.org.au
  17. 17. The Environment Institute
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