When change occurs — the Junee/Florentine Experience
My presentation today deals with the issues arising for the area manager for land management agencies on completion of a detailed scientific study.
The importance of non-wood values under the Forest Practices Code has been highlighted by B. Witte as has the method of planning adopted by Forestry Tasmania by S. Whitely.
Karst has long been recognised as an important feature in the Junee-Florentine area, with some of the significant caves being identified by caverneers and forest workers. The limestone areas have also had an important role as the source of road building material. The full impact of the karst system has not been realised in the past as can be seen from the problems highlighted by C. Mitchell.
Forestry Tasmania sets aside funds under its Conservation and Community Service Program to finance projects considered important by the area manager and relevant specialist staff. The Junee-Florentine Karst study was proposed and funded under this Program with two stages identified. The total cost of the project is in excess of $100,000.
The first stage of the project dealt with the catchment of the Junee River and has been completed by Rolan Eberhard with a draft report submitted to Forestry Tasmania. Work is now being continued on the second stage covering the northern part of the Florentine Valley.
The first stage covered an area of approximately 7,500 hectares and the report (and its maps) identified
- bedrock geology showing extent of limestone
- caves and karst hydrology summarising the cave surveys and water tracing results
- karst sensitivity zoning and natural hazards
The catchment area of the Junee system was found to be 5,500 ha.
The sensitivity zoning rated the study area into three levels of low, medium, and high and had recommended management constraints for each level. Increasing sensitivity brings with it increasing constraints on the land use within that zone and the task now rests with the relevant management authorities to consider those levels of constraint to apply within each zone and the impact of the decisions.
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The impact is in two areas:
Forest previously considered available for wood production may now be unavailable or subject to operational constraints in harvesting and regeneration. The challenge facing forest managers is to review operational techniques to enable forest operations to be conducted while meeting the objective of karst management or to protect the area from operations.
The areas zoned low sensitivity can be managed from a karst perspective as production forest under the standards set by the Forest Practices Code. Discounts will occur in this zone for features such as streamside reserves and wildlife corridors.
All areas in the medium and high sensitivity zones will be given Special Management classification for Geomorphology as a minimum. This means that where wood production will adversely affect the karst value, the harvesting will need to be modified or may even be foregone if modification is not possible. Protection will be provided in the high sensitivity zone around cave passages or entrances and in those areas of high potential for landslip.
Within the high sensitivity zone, the most significant impact is approximately 600ha of silvicultural regrowth. This area has an existing road network and has been harvested and regenerated. Some of this regeneration is now of an age and size suitable for commercial thinning.
The challenge is to develop techniques that may significantly reduce the effect of harvesting and meet the constraints required for the karst.
In the past these areas would have been logged by ground-based equipment (dozer or skidder) with ground disturbance resulting from the tracking. The introduction of cable thinning in silvicultural regrowth has shown that the harvesting can be carried out with very low damage levels to the retained trees and with only minimal ground disturbance of less than 1% (disturbance being defined as being longer than lm and deeper than 10cm).
Reforestation has been done by burning and sowing, or by windrowing for plantations. Establishment using a cultivating head on an excavator has been successfully trialled providing spot disturbance for planting.
A small area of plantation will be continued to be managed under a modified plantation regime for the current rotation and then regenerated.
Recreational Use and Tourism
Karst features in the high sensitivity zone are also those of greatest interest for recreational caving and of highest potential for tourism, eg: as part of 4WD guided tours.
There has been noticeable deterioration within some karst areas from uncontrolled access. The implementation of management control imposes costs on the administrating agency. A number of caves on State Forest will continue to be monitored for visitor level and behaviour with the potential for control.
Within the study area, Forestry has prepared a management plan for Welcome Stranger Cave. This plan highlighted the deterioration of features through ongoing visitation. The recommendations adopted included the installation of a gate system and the issue of a permit and key from the Forestry office; a system that appears to be working effectively to date but raises the question, are the indiscriminate users now just visiting another cave system and causing damage there?
Tourist potential of multiple use forest is being increasingly realized and in this location, has potential impact in major cave entrances. The study has highlighted the sensitivity of a number of caves and the need to take preventative action.
PARKS & WILDLIFE SERVICE
The study area was based on catchment area and therefore crossed administrative boundaries. Approximately 3,100ha was shown to be within Junee Cave State Reserve and Mt Field National Park.
Caves such as Growling Swallet and Three Falls Cave are accessed through high sensitivity zone on State Forest and therefore future road access and road maintenance issues need to be jointly considered.
The impact of the study is yet to be formally discussed with the Park and Wildlife Service.
TASMANIA DEVELOPMENT AND RESOURCES
Limestone has been commercially extracted from within the study area. The material has used for:
- early paper processes
- road building material both within the forest network and also for major public road construction
- agricultural supplies
The closure of Bender's Quarry in the South raised the issue of alternate supplies in Southern Tasmania and investigations were made in the Maydena area. This concentrated in the Roberts Hill / Risbys Basin area south of the study area.
Prescriptions for management need to take into account these uses controlled by parties other Forestry and may imply management costs for these other organisations. Rehabilitation of major quarry such as Junee would require careful planning and a commitment to funds by the appropriate parties.
The high quality work undertaken by Rolan Eberhard for Forestry Tasmania has provided definitive zoning for karst sensitivity in the Junee catchment.
The challenge now is for the management authorities to consider the impact of this zoning and associated recommendations. This will mean that organizations such as Forestry will need to seek new practices and systems if some of these areas are to continue as production forest.
The next stage in the process is to formally consult with authorities and prepare a position paper on the management of the area. When an approved position is reached, then the zoning will be given status under the MDC system and recorded in our Geographic Information System (GIS). The GIS system will then provide area statements for future resource reviews and also to generate maps from operational Timber Harvesting Plans.