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save the Blue Tier

erosion & water catchment

- b. finlayson


    of downhill ploughing

"While the Forest Practices Board publicises good practice, such as poughing along the contour in its annual report the reality is that where the operations are on public land, the standards of practice are much lower (figures 2 and 4)."
[click on image for larger version]


Forestry operations now taking place in northeast Tasmania under the Regional Forestry Agreement are making substantial and irreversible changes to this landscape. For many issues, it is known what the outcome will be, especially in relation to biodiversity. Large areas of complex natural and regrowth forest with a rich diversity of plant and animal species are being replaced with plantations of a single Eucalypt species.

Soils developed on the granites of the Blue Tier are sandy and highly erodible and this is recognized in the publications of Forestry Tasmania. Despite this, roading, logging and deep ripping to establish plantations is being carried out on very steep slopes, estimated to be over 50° in many areas. Significant erosion, sedimentation of water courses and deterioration of water quality would be expected to result from these operations.

In the case of water yield, the long term outcome is not known, though estimates can be obtained from hydrological models. It is a national scandal that such major irreversible changes are being put in place with no prior assessment of the long term impact, not only on water yield but the whole of the physical and socioeconomic system of this region. At the very least an environmental impact assessment and a social impact assessment should have been carried out.

The hydrological predictions indicate that for an average rainfall year, once the plantation system has become established, annual runoff will probably decline by about 30%. The decline in flow during the critical summer low flow period will be about 25%. Under real, varying climatic conditions there will be year to year variation and the impact of forest changes will be felt most severely in dry years when water is in highest demand.

The Forest Practices Code 2000 is a weak document which rarely provides definitive prescriptions for forest practices. Sufficient discretion is allowed for almost any activity to be acceptable under the provisions of the code. Not surprisingly, the standards of practice actually achieved in the process of clearing vegetation and establishing plantations are appallingly low.

The Forest Practices Board has the duty of overseeing the operations of Forestry Tasmania. Here we see an example of institutional failure where insufficient separation has been achieved between the Board and Forestry Tasmania so that the Board is unable to effectively carry out its functions.

Local residents persistently attempt to bring these issues forward and to establish meaningful debate on both the process and the manner of its execution. It is my view that the present process should be suspended across the whole of northeast Tasmania to allow for a public review by an independent panel from outside Tasmania.

B. Finlayson, Ph.D.
Centre for Environmental Applied Hydrology
School of Anthropology, Geography and Environmental Studies
The University of Melbourne
Victoria 3010

[Republished with permission of the author and editors of Upper Catchment Issues, which first published this in Vol.2#1A ISSN 1444-9560. The full report is available online]

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