Longer-term water use of native eucalyptus forest after logging and regeneration: The Coranderrk experiment

SummaryThe Coranderrk Project, located 70 km east of Melbourne, is Australia’s longest-running paired catchment study. Three small catchments (“Slip Creek”, “Blue Jacket Creek”, and “Picaninny Creek”) originally carrying old growth mountain ash and mixed species have been gauged since 1958. In 1971/72 Picaninny Creek catchment was substantially clear-felled and regenerated, predominantly with mountain ash (Eucalyptus regnans). The annual flow increased for the next 3 years (relative to the control), reaching a peak of almost 300 mm increase relative to the control catchment. Flow then declined; 8 years after the logging the annual flow had returned to pre-logging levels. Annual flow then continued to decline with a maximum reduction of around 200 mm per annum. Thirty-four years after logging the flow was still below the pre-treatment flow and showing no sign of recovery, although there were year to year variations associated with rainfall and drought. In 1972/73 Blue Jacket Creek had a “sawmiller selection” cutting in which approximately 50% of the basal area was removed. The response was a similar but muted version of the Picaninny Creek response. A statistical analysis used 1 year of the pre-treatment period to establish error limits. This showed that in both cases there was a statistically significant increase in flow followed by a statistically significant decrease in flow relative to old growth. Measurement of two of the catchments is continuing.