A landmark report calls for a fundamental rethink of Tasmania’s controversial logging practices, finding “significant” links to downstream siltation of waterways and declines in aquatic life.
Conducted by experts from the University of Tasmania and the state Forest Practices Authority, it finds a “significant relationship” between upstream clear-fell logging and forest burning and downstream sediment and declines in aquatic life.
The study, comparing 43 waterway reaches in logging and non-logging catchments, found that sedi¬≠ment run-off from logging and from unsealed logging roads had impacts as far as 10km downstream.
The findings are significant ¬≠because the FPA and Forestry Tasmania have resisted calls to recognise downstream impacts by imposing logging-free buffer zones around headwaters flowing into the habitat of threatened species such as the giant freshwater crayfish.
Despite being partly funded by the FPA and Forestry Tasmania, and involving one FPA res¬≠earcher, the report calls for a broad rethink of forestry planning and practices.
It urges a shift away from reliance on logging plans based around small parcels or coupes.
“We see an expanded focus on estate-level forest management in Tasmania as desirable,” conclude the authors, led by UTAS adjunct professor Peter Davies, a former FPA deputy chairman and adviser to the Murray-Darling Basin Authority.
“(This should be) with long-term forest practice plans complementing the shorter-term coupe/parcel-based ‚Ä¶ planning process.”
It also calls for measures to prevent run-off from unsealed gravel logging roads into waterways, and changes to the extent and intensity of post-logging forest burns.
The report was hailed as a ¬≠potential game-charger by ¬≠experts pushing for tighter forest practices. “Their own science is now backing up the fact that even a minor amount of clearing of headwaters causes sediment ¬≠issues to the detriment of juvenile crayfish,” said giant freshwater crayfish expert Todd Walsh.
“This report supports the idea of putting some decent, 30m buffers (of trees left standing) around selected headwaters, and to say that we won’t log more than a ¬≠certain percentage of selected sub-catchments.”
The state’s Forest Practices Code requires a 30m buffer of trees around waterways containing giant freshwater crayfish, but this does not apply to headwaters that feed into such areas.
The state said it, with the FPA and Forestry Tasmania, would “consider the report and its application to the Forest Practices Code, after scientific review”.
The study found a “significant relationship” between the percentage of a catchment subject to “clear-fell, burn and sow” forestry and numbers of aquatic insects, mayfly, stonefly and caddisfly, found downstream.
There was also a “clear and significant relationship” between cleared areas and the amount of sand and silt downstream.
A “significant” link was found between unsealed logging roads and a decline in the aquatic insect species downstream, while numbers of giant freshwater crayfish dropped dramatically in heavily clear-felled catchments.