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| Titel |
Runoff, sediment and nutrient dynamics at plot and catchment scale following fire in wet eucalypt forests |
| VerfasserIn |
Patrick Lane, Gary Sheridan, Phillip Noske, Chris Sherwin |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038181
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| Zusammenfassung |
| Two small mountain research catchments in SE Victoria, Australia, vegetated with wet eucalaypt forests were burnt in a wildfire in 2003. The experimental design produced a high resolution data set at plot and catchment scale on runoff, sediment and nutrient generation and fluxes, and the processes driving changes.
The key findings were:
• Annual discharge increased by around 70%, after the fire, and persisted for at least three years. At the plot scale there were orders of magnitude increases in overland flow generation under rainfall simulation
• Flow duration curve analysis showed there was no apparent change in the runoff processes delivering water to the stream network, despite the rainfall simulation results
• Suspended and coarse sediment fluxes increased by 8-9 times in the first year post-fire, but relaxed to pre-fire levels by the end of the second year
• Phosphorus and nitrogen fluxes increased by perhaps 5-6 times, and showed the same recovery rate as sediment, with the majority of both P and N transported in fine particulate form
• P enrichment ratios from plot to catchment were around 2, and the data suggests a relatively even split between organic and mineral P
• Water quality recovery was a function of the ground cover recovery
• There were no debris flows observed in these catchments despite rainfall and soil conditions that has triggered them in drier forest types nearby
• Hillslope process experiments revealed the importance of soil water repellency and the spatial arrangement of saturated hydraulic conductivity in pollutant pathway length, and these data suggested near-stream areas to be the pollutant source areas
• These experiments demonstrated that existing erosion process models do not work in these environments
• The results from this study are germane to a wet eucalypt environment under “average” rainfall conditions and good vegetation recovery
• A probabilistic approach to modelling is recommended to deal with extreme variation in post-fire rainfall and vegetation recovery over large burnt areas.
The relatively rapid recovery of these severely burnt landscapes suggests a high ecosystem resilience to wildfire. However a subsequent fire event that burnt an third of the catchments 4 years after the initial fire has resulted in an ecological response that suggests a fragility when subjected to repeated fires. |
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