MANAGEMENT PLANNING FOR WELCOME STRANGER CAVE, TASMANIA
ABSTRACT
Management issues affecting caves in the Junee-Florentine karst in Tasmania are well illustrated in the case of Welcome Stranger Cave. Much of the cave lies within a national park, but the entrance is located in an area where forestry has been the principal land use. Forestry activities and unrestricted visitation by recreational cavers have been responsible for substantial impacts on the cave. The nature of impacts are described, and management objectives and actions appropriate in the context of important and sensitive values at the site are defined. Reservation of the surface environment, control of access through gating of the cave and a permit system, interaction with users, rehabilitatory measures such as cleaning of muddied speleothems, route delineation in the cave, and monitoring procedures are actions consistent with management objectives.
INTRODUCTION
The Florentine Valley in central southern Tasmania is one of the state's principal karst areas. Some 426 caves developed in Ordovician limestone with a maximum relief of c400m are recorded by Matthews (1985). This is undoubtedly only a portion of the actual number and major new caves are discovered regularly. The karst is significant from a number of perspectives. The numerous deep vertical systems of the area are regarded by recreational cavers as some of the most challenging in Australia. Several caves have been identified as Pleistocene human occupation sites, and others are known to contain important vertebrate fossil and sub-fossil remains. The potential for geomorphological, hydrological, and other studies of the karst is largely unrealised.
A proportion of the known caves are situated within the boundary of Mt Field National Park. However, most of the karst is located outside the park in a logging concession held by Australian Newsprint Mills. The fact that logging has been the principal land use in the area since the 1930s has had serious implications for the integrity of karst values. Blockage of at least one cave entrance by logging debris has been reported, and destruction of karren forms by heavy machinery and spalling as a result of fire is widespread. Tree death in the wake of escaped forestry fires has been responsible for major landslips in both the logging concession and the adjacent national park. Landslips and the acceleration of erosion in general, as a consequence of forest clearance, appear to be responsible for the high turbidity of karst waters at several locations in the Florentine Valley. In general, however, the impact of forestry operations on karst landforms and processes, water quality, and cave biota in the Florentine Valley is poorly documented.
The conservation status of caves located in areas subject to ongoing forestry activities is clearly insecure, although recent introduction of a Forest Practices Code (Forestry Commission, 1987) provides a set of standards that give some protection for karst and other environmental values during forestry operations. However, the park or reserve status that has been conferred on other caves is no guarantee that their integrity will be respected. A good example of this is Junee Cave, the resurging point of a major aquifer fed by swallets up to 8km away, where a small reserve was created in the immediate vicinity of the entrance. This has parallels elsewhere in Tasmania, where the major portion of 'protected' caves extend well beyond reserve boundaries into areas where land uses may be inimical to the integrity of karst systems. The fact that a limestone quarry is operated only a few hundred metres from known sections of Junee Cave, and that logging has been the principal land use elsewhere within its catchment, makes the reserve at the cave entrance of questionable value if anything more than lip service to conservation ideals is intended.
In many respects the disregard for karst values that has been prominent in the history of Junee-Florentine karst is portrayed in microcosm at Welcome Stranger Cave. Prior to 1950 it was located within the boundary of Mt Field National Park, but in one of more than twenty instances where gazetted reserves have been formally revoked by the Tasmanian government (Mercer & Peterson, 1986), the area in the vicinity of Welcome Stranger's entrance was made available to ANM for timber harvesting. At that time the cave's existence was unknown, and its discovery and exploration followed clear felling of the area in 1969. As a consequence of relatively intense visitation by recreational cavers over the following two decades, substantial impacts have occurred to the underground environment at Welcome Stranger. This paper summarises the results of a recent management planning exercise at Welcome Stranger. Management objectives and actions considered appropriate in the context of important and sensitive values at the site are defined.
VALUES AND IMPACTS
The major portion of Welcome Stranger's 1650m of surveyed passage consists of a horizontal streamway leading to a sump at its upstream end. The main passage is spacious and of vadose character, but crossing it at several points are relics of an earlier phase of development in the form of upper level passages exhibiting clear phreatic forms. Paragenetic modification is evident in places and Welcome Stranger's present morphology clearly reflects a complex evolutionary history. A swallet to the east and within Mt Field National Park has been dye traced to the cave and is the principal source of the stream. Surface karst features associated with Welcome Stranger include - karren forms, dolines and dry valleys. No detailed inventory of biological resources at the site has been undertaken, but twelve invertebrates of which six are thought to be obligate cave dwellers have been recorded (Eberhard et al, 1991).
Welcome Stranger contains a comprehensive assemblage of clastic and chemical deposits, and is particularly renowned for its impressive array of carbonate speleothems. These include well-known types such as stalactites, flowstone and associated forms, as well as less common speleothems such as dog-tooth spar and tower coralloids. Clastic sediments are equally well represented, being widely distributed throughout the cave. The location of some clastic material indicates that stream aggradation, to the extent that infilling approached ceiling level, has occurred in the past. These and other sediments are of considerable interest as clues to fluctuating conditions in the external environment including glacial episodes. The fact that many of the sediments in Welcome Stranger are associated with carbonate deposits that can be radiometrically dated greatly enhances their scientific value.
The environment at Welcome Stranger has been affected by forestry in several ways. The character of vegetation at the site has been substantially modified, with the original wet sclerophyll and mixed forest of eucalypts and rainforest species replaced by a dense scrub consisting mainly of bracken, dogwood and wattle. The ridge above the cave is marked by a paucity of soil, and this has contributed to poor forest regeneration. The exposure of subsoil karren forms suggests soil loss following forest clearance, while burning-off has caused the spalling of rock surfaces and resultant damage to karren surfaces. Fires lit for forest management purposes have also had a major impact inside the boundary of Mt Field National Park where Welcome Stranger has its major catchment. Here, loss of root support in the soil, as a result of tree death due to burning, is responsible for a major landslip that extends over a distance of ~lkm and approaches to within tens of metres of the swallet that is the principal source of water in Welcome Stranger. A flux of clastic debris that has been washed downstream of the landslip partly obscures the swallet, and massively increased turbidity is now a feature of the cave stream at high stage.
A road constructed for forestry purposes that approaches to within several hundred metres of Welcome Stranger makes it extremely accessible. Moreover, Welcome Stranger is one of the few caves in the Florentine Valley that contains significant speleothems and is consequently popular as a venue both for cave photographers and introductory trips by caving clubs for newcomers to the sport. Caving club publications record some 83 trips involving approximately 483 person visits since the Welcome Stranger's discovery in 1969, but these figures probably substantially underestimate actual visitation levels. Use of the cave has almost exclusively involved members of established caving clubs due to the fact that the location of the cave has not been well known and restrictions on public access to the ANM concession. Both these conditions are in the process of changing and this gives some urgency to the need for management of the site.
The most obvious impact of recreational caving at Welcome Stranger is damage to speleothems, particularly in upper level passages and meanders. Here, traffic has left broad muddy trails across extensive areas of flowstone. In some instances the delicate rims of gour dams and crystalline pool deposits have been crushed under foot. Erosion of clastic sediments is also a problem in upper level areas, and sediments destabilised by traffic are gravitating onto adjacent flowstone and gours or into the stream. Speleothems in the active stream passage are subject to disfiguration by mud transferred from the hands and clothing of passing cavers. In some areas the process of the permanent incorporation of mud into crystal surfaces is well advanced. Less easy to quantify is the destruction of speleothems, particularly straws, due to breakage. Accounts by the first explorers indicate the existence of considerable numbers of long straws along the length of the streamway. Very few now remain that reach below the level of head-height. In some instances it has been possible to determine the extent of speleothem destruction by comparing photographs of particular features taken in the early 1970s with more recent ones.
Whilst the present condition of Welcome Stranger reflects the cumulative effect of more than two decades use, there is reason to believe that much damage occurred relatively soon after its discovery. The most intensive use by recreational cavers took place in this time, and three and a half years after the initial exploration, Skinner (1973) noted the disturbing results, commenting that it 'must have been a splendid cave before careless cavers broke many of the straw stalactites along the stream and clambered over the upper levels'. The issue of Welcome Stranger's deteriorating condition was raised again the following year (Skinner, 1974a) and some route delineation in the upper levels and cleaning of formations was undertaken. Eight months later, however, Skinner (1974b) reported that reflective markers used to define routes had been carelessly trampled.
The impact of both cavers and forestry on biological values underground is unknown, although it has been recognised that cave ecosystems are very sensitive to disturbance (Poulson, 1976; Poulson & Kane, 1977). Two important habitats - the cave stream and litter fall areas in the vicinity of the entrance - are also routes heavily trafficked by cavers. Aquatic fauna may also be affected by the recently increased turbidity of the stream.
MANAGEMENT OBJECTIVES
Welcome Stranger's significance as a feature of considerable scientific and social importance leaves no doubt that the most appropriate management orientation is towards preserving the natural values of the site. The following is therefore considered appropriate as a primary management objective:
- to protect and preserve Welcome Stranger, its physical and biological contents, and to allow natural processes to continue there with minimum disturbance
This primary objective will only be achievable if the surface environment and hydrological systems associated with Welcome Stranger are also protected. Thus, additional necessary objectives are:
- to manage the surface environment at Welcome Stranger with the aim of minimising human impacts on karst processes and features, and biological communities
- to maintain the integrity of hydrological systems associated with Welcome Stranger
Insofar as they are consistent with the above principles, three further objectives are considered appropriate:
- to provide the opportunity for recreational use of Welcome Stranger
- to encourage research into features and processes relating to Welcome Stranger, particularly where this will aid management.
- as far as is practicable, undertake rehabilitation of natural values where these have been degraded.
MANAGEMENT PRACTICES
The following management practices are considered essential if progress towards management objectives is to be made:
(1) Reservation of the Surface Environment
Further disturbance to vegetation and soil in the immediate vicinity of Welcome Stranger is incompatible with management objectives, thus the establishment of an area exempt from forestry activities is required. This should include a substantial buffer zone between the cave and any forestry activities, although the fact that clearance of re-growth in the process of establishing a pulpwood plantation has recently advanced to within several hundred metres of Welcome Stranger limits the options in this regard. It is envisaged that the area of re-growth remaining around the cave will be given formal reservation status. Welcome Stranger's principal catchment area lies within the boundary of Mt Field National Park and for this reason appears relatively secure from future disturbance, albeit that major impacts have occurred in the catchment as a result of fire.
The fact that the area recommended for reservation is contiguous with Mt Field National Park of which it once formed part, suggests that the assumption of direct management responsibility for Welcome Stranger by the Department of Parks, Wildlife and Heritage is the most logical step. This would be entirely commensurate with the high conservation values of the site and is an option that should be seriously examined.
(2) Access Control
The cost to important natural values of continued unrestricted access to Welcome Stranger is likely to be high. Ease of access and the fact that its location is relatively well known results in a high risk of damage to the cave either by deliberate vandalism or simply through visitors not being aware of low impact caving practices. Thus gating of Welcome Stranger and the use of a permit system to administer access are considered necessary. Additional advantages of a permit system include the interaction with users and the gathering of accurate data on visitation levels that are made possible.
It is anticipated that access will be restricted to members of established caving clubs, although it is recognised that caving club membership does not guarantee awareness of conservation priorities, and that Welcome Stranger has suffered considerable impacts in the past as the result of almost exclusive use by caving clubs. However, it is believed that an awareness of management aims and practical measures such as route delineation will promote greater responsibility amongst users. No limit on the number of permits issued is envisaged initially, although this may become necessary if the monitoring procedures indicate that impacts are continuing to occur at an unacceptable level.
(3) Interaction With Users
There is an obvious need for greater interaction with the principal users of Welcome Stranger, namely local caving clubs. A permit system for access to the cave will help in this respect, but the most productive interaction is likely to be that which involves cavers more directly in the management process (Middaugh, 1982). It is therefore considered necessary to actively seek input from caving clubs on possible management options and to communicate with them on an ongoing basis. The involvement of cavers in tasks such as a speleothem cleaning program is desirable for practical reasons, and may also encourage an awareness of cave conservation issues and an appreciation of management concerns.
(4) Route Delineation & Rehabilitation
It is anticipated that practical efforts to reduce impacts underground will consist primarily of route delineation in upper level passages. Although the use of reflective markers to define routes through sensitive areas in caves has merits in some circumstances, previous use of this technique in Welcome Stranger has proved ineffective in confining traffic (Skinner, 1974b). An alternative method involving the use of string lines on either side of a narrow route is likely to be more successful. In defining routes through particular areas, questions will have to be resolved, such as: the best route where a choice exists, whether it is preferable to avoid flowstone at the expense of disturbing clastic sediments, whether a particular route can be effectively cleaned, and the possibility of barring entry to some highly sensitive areas, especially where these areas can be viewed adequately without the need to approach closely.
An additional management priority that has been identified is the need to effect rehabilitation of speleothems where these have been degraded. Damage in the form of breakages is generally irrevocable, but rehabilitation may be possible with the use of water and brushes where speleothems have been muddied. There is a huge backlog of this work to be undertaken and it can probably only be achieved if caving clubs are involved. Periodic attention will also be required in the future as effects of subsequent use accumulate. It is anticipated that problems will arise in cleaning certain sections of the upper level passages due to the risk that water used may drain onto other sensitive areas and cause further muddying. In other instances, cleaning is impossible because of permanent disfiguration as the result of the incorporation of mud into crystal structures. Rehabilitation of clastic sediments that have been disturbed is also desirable, though it is not yet clear how this may be best accomplished. In the interim, reducing the rate of degradation of clastic sediments by route delineation is an obvious need.
(5) Monitoring Procedures
It is on the basis of monitoring that the effectiveness of measures adopted in an effort to reduce impacts will be judged, and decisions made as to whether visitation levels need to be limited or further cleaning and route delineation are required. Photo-monitoring is a technique that has the advantage of allowing relative objectivity in identifying changes (Larson, 1978; Stout, 1978), and a photo-monitoring program to be undertaken annually has therefore been designed for use at Welcome Stranger. It is recognised, however, that the technique only monitors a fraction of the area potentially subject to impacts, and the role of more subjective assessments based on visual impressions of the cave as a whole is also considered important.
(6) Other Uses
The possibility exists that in the future Welcome Stranger will be considered as a venue for tourist cave development or adventure-type tours. Developing Welcome Stranger for tourism would involve major impacts and any such proposal should be very closely scrutinised in view of the likelihood that potential returns would not compensate for the cost to natural values in the cave. In the case of adventure-type tours, these may in theory be comparable with management objectives but only insofar as substantial new impacts are not involved. Specific guidelines as to numbers, appropriate behaviour and areas to which access is allowed would be required.
The implications of any proposed scientific research at Welcome Stranger should also be carefully considered. Research should be encouraged for its intrinsic worth and the value it may have in identifying management needs, but activities such as removing speleothems for radiometric dating or the collection of cave invertebrates where only small populations exist are potentially major impacts on a cave.
Thus, any research proposals should be assessed on a case by case basis taking into account the nature of the proposal, its likely impact on the cave, the value of the results to the broader community, the scientific worth of the researchers and their capacity to extract maximum information from finite resources.
ACKNOWLEDGEMENTS
The impetus for this management study came from Kevin Kiernan, and his contributions in the form of plentiful comments, advice and encouragement are gratefully acknowledged. Ron Mann is acknowledged for making available photographs taken shortly after Welcome Stranger's discovery, and Phil Jackson and other members of the Southern Caving Society are thanked for the use of their cave survey.
REFERENCES
EBERHARD, S.M., RICHARDSON, A.M.M., & SWAIN, R., 1991, Invertebrate Cave Fauna of Tasmania, Report to the National Estate Office, Canberra
FORESTRY COMMISSION, 1987, Forest Practices Code, Forestry Commission, Hobart
LARSON, C.V., 1978, Photo-monitoring as a cave management tool, National Cave Management Symposium Proceedings, Adobe Press, Albuquerque, pp. 96-103.
MATTHEWS, P.G., (ed), 1985, Australian Karst Index 1985, Australian Speleological Federation, Sydney
MERCER, D. & PETERSON, J., 1986, The revocation of national parks and equivalent reserves in Tasmania, Search, 17(5-6):134-140
MIDDAUGH, G.B., 1982, The state of the art in management planning - a case for caver involvement, National Cave Management Symposia Proceedings, Pygmy Dwarf Press, Oregon, pp211-213
POULSON, T.L., 1976, Management of biological resources in caves, National Cave Management Symposium Proceedings, Speleobooks, Albuquerque, pp46-52
POULSON, T.L. & KANE, T.C., 1977, Ecological diversity and stability: principles and management, National Cave Management Symposium Proceedings, Speleobooks, Albuquerque, pp18-21
SKINNER, A., 1973, A problem of deterioration, Speleo Spiel, 78:2-4
SKINNER, A., 1974a, Welcome Stranger and its problems, Speleo Spiel, 87:4-5
SKINNER, A., 1974b, Junee-Florentine - 14/9/74, Speleo Spiel, 95:3
STOUT, D.L., 1978, A photo-monitoring system for Horsethief Cave, Wyoming, National Cave Management Symposium Proceedings, Adobe Press, Albuquerque, pp104-107