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The Forest Practices Authority

Planning for earth sciences special values - an introduction

This is a brief guide to how coupe planning in the Tasmanian forest practices system takes earth sciences issues into account.

Why do forest practices plans need to take account of earth sciences special values?

To prevent unacceptable rates of erosion and soil degradation (e.g. compaction); to maintain water quality both for ecological and social/economic reasons; to maintain water flows within the range of natural variation; and to prevent damage to sites of special scientific interest.

The basic protocol followed by Forest Practices Officers

Once an area (coupe) has been selected as being potentially suitable for harvest in a three-year plan, a Forest Practices Officer (FPO) will normally walk through the coupe to determine its special values.

To address earth sciences issues the FPO will ask questions like:

  • Are the streams correctly mapped?
  • What classes of streams are present?
  • Do any of them show unusual features like extensive erosion or steep-sided gullies?
  • Are the streams within a town water or domestic water catchment?
  • What is the underlying geology?
  • Does the observed geology match that shown on geological maps?
  • On the five-class erodibility scale, how do the soils classify?
  • Is soil erodibility going to be an issue when constructing roads, building stream crossings, or cultivating for plantations?
  • Is limestone or dolomite present on the coupe or nearby and if so, are there karst features like sinkholes or caves?
  • What are the maximum slopes?
  • Are landslides present and what is the landslide risk?

When answering these questions, many of which are formally included in the earth sciences special values evaluation sheet which the FPO must complete for each new coupe, the FPO will make use of many published documents, including the book Forest Soils of Tasmania, the Forest Soils Fact Sheets , the Tasmanian Geoconservation Database  and the Karst Atlas. But also important is the FPO's own experience of assessing and managing earth sciences issues.

Some features such as the presence of caves or landslides require consultation with an FPA earth sciences specialist, and in these cases a formal notification is submitted to earth sciences. This notification will include draft prescriptions to deal with those special values noted (e.g. measures required to protect an eroding stream, or a reserve around a significant geological feature like a cave). The notification will be assessed by earth sciences specialists at the FPA and if a field visit is required issues will be sorted out by a joint visit to the coupe.

The management prescriptions required on other coupes may be decided by the FPO himself or herself, usually in consultation with colleagues - not all plans have to be submitted to the FPA for comment or endorsement. However, FPA earth sciences specialists are always available to give advice on any coupe if required.

When preapring a forest practices plan, Forest Practices Officers map the streams and take note of any unusual features such as this stream which disappears undergound.
Forest Practices Officers notify the FPA when they identify a special value which needs careful management. Here, the FPA's earth science specialist provides advice on a stream in a second rotation plantion.

Correct estimation of soil erodibility is crucial to correct interpretation of many Forest Practices Code guidelines, and training courses for FPOs put a large emphasis on correct soil identification, so that environmental damage is limited in forest operations.

Apart from the Forest Practices Code itself, there are a number of formal documents available to FPOs that are obligatory to use when planning coupes. Examples are the Class 4 Stream guidelines , the Forest management on soils in basalt talus  and the Guidelines for forestry operations on soils formed in dolerite slope deposits (Dolerite talus).

Once the FPO has completed the earth sciences special values sheet, and received a reply from the FPA, or satisfied himself or herself that FPA consultation is not required, he /she then finalises prescriptions to protect the special values identified. These prescriptions are written into the forest practices plan which covers all planned operations from roading to harvest and revegetation.

Karst features, such as this arch at Trowutta, require special management to protect them.
Sometimes caves contain special values other than earth science values, such as this platypus nest.

After the plans have been certified and harvest has begun, earth sciences specialists are unlikely to have further involvement, but occasionally a feature or problem is discovered during harvest operations and further advice is given, or a field inspection is made, usually resulting in a formal variation to the original plan.

Once operations are completed, earth sciences specialists may conduct independent monitoring to check that recommendations have been applied and that measures taken have been effective in protecting environmental values. The earth sciences specialists may also be involved in compliance checks made by FPA compliance officers. Examples of studies undertaken include investigations into the sources of chemical contamination in streams, and erosion in east coast plantations subject to high-intensity rainfall. Investigations may also be made if difficulties arise during coupe harvest, or if members of the public make a complaint about planned or on-going forestry operations.

The application of the Forest Practices Code and earth sciences guidelines in a coupe is demonstrated step by step in a paper describing the coupe planning process written by FPA scientist Peter McIntosh and FPO Terry Ware Taking account of special values in the coupe planning process - an example from the southern forests, Tasmania.

The FPA's earth science specialist training forest supervisors in class 3 stream identification and management.

Apart from giving advice, earth sciences staff spend about a third of their time on research, to keep ahead of forest management issues and to enable them to continue to learn from the larger scientific community. They also spend time on training FPOs, foresters and contractors, not only by giving formal courses but by arranging field days to exchange knowledge and experience on special topics such as culvert design, assessing landslide risk or sinkhole protection.

Content last modified May 2, 2012, 10:06 am