CAVER'S IMPACTS   -   SOME THEORETICAL AND APPLIED CONSIDERATIONS

Andy Spate, Investigations Officer - Karst, New South Wales National Parks and Wildlife Service, South Eastern Region
Associate Professor Elery Hamilton-Smith, Department of Leisure Studies, Phillip Institute of Technology, Bundoora, Victoria, 3083

INTRODUCTION

We have long held the view that caves, their contents and values are more at threat from cavers and their activities than they are from the activities of quarry operators and other users, or abusers, of karst areas (Hamilton-Smith 1962, Spate 1973, 1989). Of course, when there are impacts from non-caver users, then they may well be more extreme, as in, for example, the dumping of sheep in both Three Sisters Cave and Earls Cave in the Mount Gambier region, logging in Junee-Florentine and the appalling destruction at Mount Etna, amongst other examples, but these each affected a limited number of caves rather than the thousands damaged by cavers although these latter may have been minor impacts. But they are across the whole system.

The activities of cavers have produced widespread impacts from Tasmania to the Kimberleys and from South-western Western Australia to Chillagoe. Unfortunately these impacts are not well documented - and it is not easy to quantify and subsequently document them. It is easy to say that the responsible and properly organised cavers, that is, those who belong to speleological societies or caving clubs, have minimal impacts and that the problems we see arise from other users. But, this is simply not true. Probably more importantly, it is usually the dissemination of information about caves from these organisations or their members which leads to wider public interest in caves. This quickening of interest of the wider community may not be deliberate but it does occur in spite of the stated conservative policies of caving clubs.

We consider here the activities of all cave visitors - researchers with universities and government departments, cave area managers and other staff, speleological societies and their members, scout and other youth groups, and casual cavers such as family groups and other cave visitors who cannot easily be classified. Although the last are often considered by organised speleologists to be a 'yobbo' element, our experience suggests many of them have a better attitude to cave conservation than many of the more identifiable people.

The one group we exclude are those visiting conventional tourist caves, because these caves have been hardened against visitor impacts; in other words, management impacts replace visitor impacts and that is a different question - even if the impacts have been severe. Even this definition causes problems by truncating the spectrum of cave users and the dividing lines between conventional tourism, adventure caving and wild caving are fuzzy indeed.

There is a truism (from Tom Aley's famous 1975 paper 'Caves, Cows and Carrying Capacity') that has been increasingly re-iterated by Australasian cave managers in recent years - caves have a zero carrying capacity. Whilst this is not entirely true, for most practical purposes it is so and the re-working of the ASF motto by SRGWA into 'Whatever we have now is more than we will have tomorrow' is entirely apposite.

Before dealing in more detail with impacts upon caves, we will firstly review the history of conceptual thinking about recreational impacts upon natural resources. This provides a backdrop against which to consider cave-specific problems.

CARRYING CAPACITY AND OTHER MANAGERIAL MODELS

The original idea of carrying capacity was derived from agricultural practice, in which it was defined as the maximum number of animals of a given species which might populate a given area on a sustained basis (Dasmann 1964). Given that many park managers come from biologically-based education and ideology, it is not surprising that the notion was transferred to recreation management, even though it was already being seriously questioned and found wanting in its pastoral fields of origin.

The central problem of carrying capacity as an idea is that it rests upon the assumption that any one environment has a fixed limit to the amount of use which it can withstand and hence has a fixed population which it can support. But this is just not true. Timing and patterns of use, range size, cyclical and other natural changes in climate and vegetation, managerial intervention and a range of other problems all mean that carrying capacity is just another beautiful idea murdered by a gang of ruthless facts.

Nevertheless, several thousand research papers have been published on recreational carrying capacity since the turn of the century. One important turning point was marked by Wagar's (1964) argument that the concept could not usefully be considered only in ecological terms, but that the social dimensions were vital. This spurred students of recreation studies to new efforts in dealing with the idea of 'social carrying capacity', but a further turning point came with Burch (1984), and his statement that 'never has so much been said by so many on a topic of such inconsequential irrelevance.'

Essentially, Burch argued that the concept has no conceptual or theoretical basis, and hence cannot support valid research or sound management practice. At the same time, it is clear that there remains a genuine problem for resource managers - recreational use does have potentially major impacts upon the natural environment, and managers must find ways of controlling these so that they remain at an acceptable level.

A much more comprehensive review of the history of the carrying capacity idea and its various problems is provided by Stankey and McCool (1989), and it concludes with the words 'the term is no longer useful in guiding research or management'.

They and others now argue that the issue is one of identifying the quality of recreation experience which is to be provided in any given environment, and determining the environmental conditions which are then appropriate. Thus, thinking has moved away from a concern with the setting per se to a concern with proper formulation of managerial objectives and with the proper implementation of these objectives.

Two parallel series of planning and management tools have now emerged. One series, including the well-known Recreation Opportunity Spectrum (ROS) and the Canadian Visitor Activity Management Process (VAMP), is concerned with identifying specific classes of opportunity, providing a basis for characterising these and allocating resources to them. These tools are central to enhancing the quality of recreational experience, but irrelevant to questions of environmental impact. The other, which includes the Limits of Acceptable Change (LAC) and Visitor Impact Management (VIM) processes, is concerned with defining desired environmental conditions and procedures for maintaining these. They are thus central to environmental impact management. Ideally, either ROS or VAMP would be used in tandem with either LAC (initially developed as a companion to the ROS) or VIM.

Each of these have been subject to various problems in implementation, usually because one or another have been seen as a comprehensive planning process rather than as simply a tool to be utilised within an appropriate planning process, or sometimes because one of these tools has been used for a purpose for which it was never intended and is in fact inappropriate.

Turning to a more detailed analysis of each, the ROS (Clark and Stankey 1979) essentially identifies a spectrum of recreation opportunities generally ranging from relatively undisturbed natural environments for low density recreation use to highly modified environments for high density use. It is based in a series of theoretical ideas which assume a relationship between the preferences of individual recreationists and the natural settings within which recreation occurs, and this has proved problematic; it demands further research (Driver et al 1987). It is worth noting here that the ROS has stimulated some attention to specialisation analysis, as a relatively crude means of establishing a typology of recreationists, and this method has been applied to consideration of cavers in Australia (Hamilton-Smith 1981).

The Cave Classification Scheme (Worboys et al, 1982) developed in Australia is in effect a variant of the ROS approach. Like other applications of the ROS approach, there have been attempts to apply it to issues of significance or conservation management - something for which it was never intended and is totally unsuited. What it can do is provide a basis for allocation of management resources, and because it was designed for uniform terminology, to help communicate managerial decisions to cave visitors. Hamilton-Smith (1981) demonstrated the potential relationship between this classification and specialisation analysis.

The VAMP (various authors, in Graham and Lawrence 1990) is less familiar to Australians at this point in time. Rather than starting from opportunities as does the ROS, or even from any assumption of a spectrum as is inherent in specialisation analysis, it starts by identifying various patterns of visitor behaviour and interests, then specifies for each visitor category the demands upon and expectations of environmental opportunities and managerial initiatives.

The inherent logic of commencing with identification of visitor categories appears to provide a potentially better process than ROS. It is already proving to be a very powerful tool indeed, although its comprehensive implementation demands a far more sophisticated data management system than is yet available in Australia. The conceptual basis of VAMP is in fact very akin to that of much market research with its focus upon the identification of 'market segmentation'.

Both the LAC (Stankey et al 1985) and VIM (Graefe et al, Kuss et al, both 1990) processes have been developed as tools to help the manager identify desired environmental conditions and to manage in a way which will maintain these. As noted above, either can be used in tandem with ROS or VAMP, and indeed, should be. To clarify the nature of these processes and as an example, VIM comprises the following steps:

• Review and summarise existing situation
• Review management objectives and produce specific area objectives which specify anticipated visitor experience and resource management conditions
• Select key indicators and measurements to assess impacts
• Set standards of achievement for each indicator
• Compare existing conditions with standards
• Identify causes of undesirable impacts
• Identify management strategies to deal with causes of undesirable impacts
• Implement and monitor

In summary, it seems that the profitable directions which managers might pursue include:

1. developing satisfactory typologies of both environments [caves] and visitors
2. learning how to adequately define management objectives for specific environments [caves] or categories of environment [cave classes]
3. establishing management practices which will insure the proper implementation of these management objectives

Speleologists, as one of the 'organised' visitor categories, can play a role in furthering this improved management. However, there are problems in this. Some minor ones are to do with lack of expertise in or understanding of resource management, but the most important is to do with conflict of interest. Speleologists have an inherent interest in maintaining their own access to caves, often at the expense of other potential visitors. We will vary greatly in the way in which we might express this, but we do no service to ourselves or anyone else if we deny it.

Following a review of the impacts of cave access by all cave visitors, we will return to the question of strategies which might be pursued to reduce such impacts.

IMPACTS OF CAVE USE

As we have noted above we are confining our attention here to the end of the user spectrum away from cave tourism and paid adventure caving. It is very surprising (considering the various ethical codes, do and don't lists and the acceptance by many, if not all cavers, that caving does affect the cave) that there has not been more objective discussion, measurement or monitoring of what these supposed impacts might be. We have surveyed a great deal of the Australian, United States and British cave literature as well as some of that from other countries and found very little other than the 'motherhood' type of statement above.

It is worthwhile to consider what it is that makes up a cave environment and what makes it different from aboveground situations. Firstly, we have no short wave-length radiation - no visible light or infra-red. Therefore energy sources to support life must be derived from material washed or carried in from outside or from very low energy chemical reactions such as the oxidation of iron and similar chemical species. The absence of light of course means no photosynthesis and ecosystems must therefore be based on a narrower base than those we are used to on the surface.

Secondly, the cave and speleothem development processes rely upon a flow of water and carbon dioxide from the atmosphere, through the soil and rock and thence to the cave. Maintenance of an adequate soil and vegetative cover is needed to maintain the cycle of water and carbon dioxide through the system. The atmosphere contains about 0.03% carbon dioxide, soils up to about 10% (for the very best soils in the very best climates!) but more usually around 1-3%. Cave atmospheres - at least the ones humans get into - tend toward equilibrium with the outside atmosphere but their confined nature and the constant degassing of dripping and flowing waters means that their carbon dioxide content is commonly greater than atmospheric and up to around 0.5% although of course much more highly enriched caves are well known in New South Wales.

Thirdly, the cave climates tend to be isolated from the outside world - although again there are many exceptions and the range of degrees of isolation produce a wide array of specific environments. Caves tend to be at the mean annual temperature of the rock mass that encloses them (remember the volume of rock is usually much, much greater than the volume of cave). This temperature is usually close to the mean annual temperature of the area in which the caves lie and in most of our caves the temperature range will only be a degree or less once away from the entrance - the range is often less than the accuracy of our thermometers! There is normally a plenitude of water vapour in the air and the relative humidity will tend toward 100% - saturation. Again the accuracy of water vapour measurement required exceeds the specifications of our instruments.

The physical characteristics of cave contents - speleothems, sediments, fossils and so on as well as archaeological materials and cave biota (simple plants and more complex animals) living in caves will have been produced by, and in equilibrium with, these various relatively unchanging environmental characteristics. Lack of variation means that systems are not well able to cope with greater change than they are used to.

Often it is the very unchanging or at least buffered cave environment which permits the preservation of sediments, fossils, bones and speleothems. We could liken caves to a refrigerator - things won't keep forever inside but they do keep a hell of a lot better if we don't leave the door open or modify the system environment be turning the power off.

Fourthly, the conditions under which many cave sediments are emplaced are often 'quieter' than surface environments and their densities may be low or they may be delicately stratified so that disturbances such as trampling may markedly damage the characteristics of the site. This is particularly so of airborne deposits and bones in owl roosts.

One way of looking at this is to recognise that the typical cave is essentially an extremely low energy environment - it is for all essential purposes over the short term a homeostatic one with little energy input. So, even the entry of one person with their own body temperature, movement and usually at least one source of light constitutes a major change in the energy regime. This will have little or no impact upon the bedrock, but a major impact upon micro-climate and hence a potentially major one on various of the cave contents.

We can consider user impacts on caves and their contents in two ways. Direct physical impacts such as compaction, breakage, sampling and disturbance to bats are widespread and usually comparatively obvious. The indirect effects of environmental modification may not be so obvious and may have very far-reaching effects. The essentially non-renewable nature of most cave resources means that few impacts are reversible through the application of time or technology. Some impacts may be reversible - for example we could block up a dig - but the results of that original modification may have led to irretrievable damage if, say, a colony of bats had left the cave because of climate change and had been unable to find an alternative site.

Stitt (1977) points out that increasing the numbers of people using caves may combine in three ways. Cumulative effects are those where the impacts simply add together; synergistic effects are those where two or more effects combine and produce an effect greater than would be expected if the two had occurred independently. Where an impact has no influence on the effects of other actions it is said to be independent. All three of these types will be occurring throughout a cave visit. We tend to forget that synergistic effects (= multipliers, snow-balling, positive feedbacks) do occur in non-mechanistic systems. This is especially true of compaction and liquefaction and other types of sediment disturbance and probably of much else. Stitt then argues that the "impact of a party of ten is more than twice that of a party of five' - we cannot help but agree.

As many natural materials possess some 'elasticity' of some of their properties smaller parties are better than large even if the total numbers of passes is as high or higher. Whether this is even partly true of cave ecosystems is a matter for conjecture although it can be demonstrated for relatively simple agricultural systems and for sand dune communities. Casual observation, but by many observers, seems to indicate that the earliest visits to new caves will rapidly reduce the abundance and diversity of cave invertebrates. That is, there appears to be a threshold of disturbance which is soon reached - and then the community collapses.

Dave Gillieson (pers. comm.) cites the Russenden Cave at Texas as an example. This cave when first discovered had a flat, silt floor rich in organic material 10-15 cm deep. The first trip numbered five, the second 12 and after about six trips the total visitor numbers had reached about 100. One of us (EHS) collected a rich invertebrate fauna. By the sixth trip the fauna was demonstrably impoverished, water flow had been channelised and the low density silt had been compacted over large areas. This sort of story seems common over large areas with Byaduk Caves, in the lavas of Western Victoria being another 'good' example.

Frank Howarth (1981), in an interesting paper on the conservation of cave invertebrates, asks the question 'How does one sensitise cavers to respect the resources within caves?' and goes on to say:

My experience has been that it is fairly easy to instill a conservation ethic within the sphere of interest of one individual but much more difficult to instill such a feeling across many disciplines in any one individual. I have introduced many Hawaiian biologists to the wonders of Hawaiian caves, and all have been quick to agree with my own conservation feelings on biological resources, but some have been slow, even recalcitrant, to understand that there might be other resources in the caves and blithely trample through archeological, geological, or other wonders. Conversely geologists and archeologists have quickly grasped the significance of cave resources in their own field only to trample unknowingly through biological resources. Such sensitivity seems to accrue only after long experience in caves, that is only after the explorer has seen the degradation of cave resources for himself does he realise he is part of the problem.

On a recent field trip with a biologist who quickly became impressed with cave fauna and who carefully avoided breaking tree roots or disturbing the animals, I pointed out some rather nice sand castles built in the volcanic ash by dripping water. His reaction to this relatively rare phenomenon in Hawaiian caves was to suddenly stomp and kick his way through the whole display saying: 'Sand castles! They look like just piles of sand to me!' I protested his actions rather vehemently, but I am afraid that I did not convince him that I did not convince him that sand castles in caves have any use or aesthetic value.

In another instance I was in a newly discovered pristine cave with one of the most effective conservationists in Hawaii who is also an astute field biologist. He had gotten ahead of me, and imagine my shock when I rounded a corner in the cave passage and came upon the word SHIT written in 10 cm high black letters in a small patch of white cave slime. I caught up with him and gave him my lecture again on how graffiti begets graffiti in caves, but he was quite unconvinced because he felt that it was not a graffiti, because he was marking the location of a small pile of rat droppings which had some interesting insects on them and furthermore this was a pristine cave without graffiti and it was unlikely that graffiti artists or vandals would find it. Both of his arguments were patently false of course, and after some consideration I erased the word even though it virtually destroyed the remains of a rather nice patch of slime and its inhabitants.

There seem to be some interesting lessons in these two accounts!

Direct impacts of use

These impacts are produced by direct physical processes and may affect physical, aesthetic, archaeological and biological attributes of the cave environment.

Although most cavers have respected the integrity of speleothem decoration, there are the exceptions. We are all familiar with caves which have been almost totally stripped of decoration. Scotts Cave and Baldocks Caves at Mole Creek, Honeycomb Cave at Murrindal and Cotter Cave near Canberra are good examples. The first two of these were formerly show caves and are the worst Australian examples of the phenomenon, also noted in the United States (Ross Gurnee, pers. comm.), that the worst vandalised caves are abandoned show caves. It is quite remarkable to look at the photographs of these caves taken at the turn of the century by Stephen Spurling III and recognise the former aesthetic qualities of these caves, including probably some of the finest examples of conulites (Hill and Forti 1986:30-31) seen in Australia.

Another example of the destruction of conulites in Australia is at Dalleys Cave, Murrindal, where although less spectacular, the occurrence there was one of the largest and most complex yet known - now trampled into total extinction.

Honeycomb Cave is also an interesting example, in that it was first discovered and its value recognised in 1907 (Hamilton-Smith 1991a). It was concealed from view at that time and only rediscovered by the current generation of cavers in 1960. Sadly, its beauty then lasted less than a year.

Pool crystals were deliberately removed from Punchbowl Cave, Wee Jasper, in the late fifties or early sixties for placement in a museum so that at least some of the material would survive trampling (Jennings 1964). Whether the removal triggered less respect for the site is unknown - but this is possible.

The 'rock-hound' type caver is a particular problem. Examples which come to mind in Australia include those apprehended by a landholder after taking a sackfuls of speleothems from a cave at East Buchan; those responsible for extensive quarrying of pool crystal (which later appeared on the retail minerals circuit) from Federal Cave at Buchan and the individual who tried to market fossils from Victoria Fossil Cave, Naracoorte (but was blocked simply because one of us looked in the window of a mineral shop and recognised the material). But think of all of us cavers who have one or more pieces hidden away or sitting on their mantle shelf.

We do not intend to enter into any discussion about the ethics of bolts and similar devices but we do wonder when cavers will start to protect columns or stalactites used for ladder belays. It is interesting that even SRT ropes can have direct impacts on caves as in the deep grooves worn in the top of last pitch in Midnight Hole. These have developed to such an extent that there is a real danger of the permanent jamming of the rope.

The very acts of movement on feet, hands, knees or prone bodies crawling can markedly change calcite or other mineral speleothems on cave floors, walls and ceilings. Examples of the destruction of micro-gours can be seen throughout NSW. More commonly, and frequently of less apparent concern to users, are clastic (clay, sand and silt deposits = 'mud') deposits. These may be compacted, liquefied, eroded after disturbance or transported to other places. Often quite beautiful and delicate structures - notwithstanding any scientific values in addition to their aesthetics - may be destroyed. Transport and compaction may lead to the dimpled, 'brain-surface' pathways common in many heavily used areas.

Sometimes transport from elsewhere in the cave can lead to the development of a compacted pathway on which the surface actually builds up. One such pathway, in Signature Cave, Wee Jasper, has built up by about two centimetres in the last four years by this process.

The impact of feet and bodies are not necessarily confined to unconsolidated sediments. Many a weta or other invertebrate has perished underfoot. The changed physical state of the substrate may also preclude its use by burrowing species. A good example of the latter has occurred at Mount Widderin Cave, Skipton. Hamilton-Smith (1968) recorded an important invertebrate community living on the loosely consolidated floors of this cave. This community provided a virtually unique opportunity for long-term research. However, the landholder concerned has encouraged (for a small fee) indiscriminate and unmanaged wild caving at this site. When last visited by one of us, the floor was trampled to a virtually polished surface; no fauna at all was seen.

Mud transfer from sediment areas to clean surfaces and to stalactites and stalagmites is an ongoing problem and together with speleothem breakage is the most obvious and intractable sign of degradation. It is, of course, a difficult issue as caves are alternately clean and 'dirty' and changing of overalls every five minutes is never going to be popular! However, simple precautions like using the back of one's hand for balance if it is needed can markedly remove the problem. Speleothem breakage can be accidental or deliberate but today's cavers probably break very little deliberately. However on popular routes and in confined spaces damage can be ongoing.

Anemone Cave at Wee Jasper provides an example of almost wanton destruction of a beautiful speleothem by mud transfer and stalactite breakage. There are two routes through this tiny cave. One lies through the 'Anemone' itself - a perfectly round hole fringed with white calcite stalactites - the other by an unexciting low ramp. The Anemone is all but destroyed and caked with brown mud. In most heavily used caves as well as many highly protected and little used caves one can find evidence of highly inappropriate behaviour - that of mud fights. This as a cave damaging pastime appears to have persisted where other forms of vandalism such as littering have markedly declined. Is it something primeval in being dirty and having a plentiful supply of ammunition ready to hand?

Erosion of unconsolidated materials and polishing of limestone by moving bodies can be seen in many cave areas. At Bungonia and Wee Jasper, for example, polishing has become so pronounced that in caves such as the Grill and Punchbowl slopes that could once be easily climbed are now difficult - if not dangerous. In Dog Leg Cave erosion and reworking of the stream bed has very markedly changed the course of the creek. This, coupled with the positive delight many visitors get out of wallowing in the pools, does not appear to have unduly inconvenienced the invertebrates found in this cave in spite of APS' concerns of 15 years ago. These unique Gondwanaland species must be remarkably resilient to have survived the impacts of probably thousands of visitors.

Here we have the ambiguity of a population, which one would expect to be particularly vulnerable, surviving considerable disturbance. However, one cannot generalise from this. In the first place, the cave has an active, if non perennial stream - it is a much higher energy environment than most caves to begin with. Secondly, the changes which result from disturbance are probably within the range of the normal variation on the stream environment changes in temperature, sediment load and nutritive content. One could only fear the result of other changes which might have occurred had a cigarette butt or a spill of battery acid polluted the pool - both of these will produce changes considerably outside the normal parameters.

Erosion of surface soils around entrances and entrance facies themselves is particularly marked in many areas. Large volumes of material moved into caves not formerly receiving such slugs of sediment is undesirable.

Changes in vegetation over caves consequent upon recreational activities are not known to have produced underground changes in Australia although cavers have been implicated in unnecessary vegetation destruction in some areas (see, for example, Anon 1987). Other examples include gathering wood for campfires in the aridity of the Flinders Ranges, the chopping down of a rainforest remnant species at Murrindal simply for greater ease of access, and the degradation of the doline at Corra-lynn Cave, Curramulka over the 1954-60 period. Destruction of vegetation around entrances may have led to accelerated erosion on those sites. However, the formalisation of camping and access at Bungonia, for example, has allowed remarkable recovery of the understorey in that area which has certainly improved the aesthetics of the area if nothing else.

Digging has had a direct effect on many Australian caves and it would be interesting to catalogue the various efforts to see how much new cave has been revealed. At Yarrangobilly and Bungonia stratified sediments containing sub-fossil bones have been destroyed. Elsewhere digs have produced indirect effects - these will be discussed below.

Direct disturbance of bat populations by cavers (and bat researchers) has lead to dramatic changes in their distributions and reductions in their populations. We must plead mea culpa and state that we conducted research into bent-winged and horseshoe bats in eastern Victoria in the 1960s and may have contributed to the species decline in the latter species. On noticing that decline we changed our practices and there now seems to have been an upsurge in the species numbers and a re-occupation of abandoned roost sites (Hamilton-Smith 1970).

Mohr (1975) asks the question '... does caving disturb bats?' He goes on to point out a number of ways in which cavers interfere with roosting bats and quotes rates at which disturbed bats loss their fat reserves through the winter months.

Sluiter and Van Heerdt (1957, 1964) record their long-term observations of bat populations in the Southern Netherlands, and demonstrate how a continuing decline in population was reversed by cessation of population disturbance.

Cave bat numbers seem to be increasing again in eastern Australia but they are still very vulnerable to direct interference (Hamilton-Smith 1991b). In the past our major concerns were for the sanctity of the maternity sites so important to the populations in the summer months. The over-wintering sites such as Thermocline Cave at Marble Arch are also critically important for the life cycle of these, and other, species and should be avoided if possible (Hall 1982).

The actions of managers, be they well-intentioned cavers or the paid kind, often exert direct impacts on cave environments in an effort to improve some deleterious situation. Very many gates have been 'installed over the years with very little thought on how they might limit bat movements and nutrient flows and completely change cave environments. Webb (1984) presents a particularly good account of how a cave was much modified by the heavy hand of management. During the work that one of us (APS) carried out with others in 1991 on the resources of Kubla Khan in Tasmania it became obvious that a gate, with a low sill, installed by cavers had halted the flow of leaf litter and other material to the waiting jaws of the invertebrates below. How significant this effect is we do not know. It may be that the balance is at least partly redressed in this instance by the material actually carried into the cave on boots, clothing and SRT gear.

Williams (1975) first drew attention to the role of an artificial barrier across the streamway at Waitomo Caves, New Zealand, in causing a massive decline in the famous glowworm population. This has since been dealt with, but continued monitoring has periodically revealed damaging impacts of other minor well-intentioned actions.

Removal of gates and walls at Jenolan has permitted bats to return to previously abandoned roosts in the northside tourist caves (Ernst Holland pers. comm.). Similarly modification of the gate on Cotter Cave, near Canberra, has allowed bats to return to their former home [it is will known that bats exhibit considerable philopatry ('love of home') - do they constantly explore their environment or is there some 'racial memory' drawing them back to their former homes?].

Indirect impacts of use

As indirect impacts are frequently subtle and of long duration the effects may be corresponding subtle and long-term. Often systems, particularly biological systems, show threshold effects when perturbed. That is, the disturbance can continue for some time before the system shows signs that it is in trouble. Often the system collapses catastrophically and irretrievably.

Some indirect impacts may be deliberate, for example changing water or airflows through digging. The use of explosives, which has been all too common in Australian caving practice, normally leaves a residue of oxides of nitrogen - the impact of these upon invertebrate populations could be disastrous. Indirect impacts may also be accidental as in the introduction of nutrient sources such as chocolate flakes from Mars Bars!

The impact of underground camping or other massive assaults on the energy system is even more extreme. Cigarette butts or ash and spent carbide or dry cells are all magnificent sources of insecticides - quite apart from the aesthetic impacts of bad caving practice (Howarth 1981). Howarth says that "This last perturbation [human visitation] needs elaboration, for its effects are probably least understood, and yet disturbance seriously affects a greater number of caves [than quarrying, pollution and so on]".

Having brought up the subject of food we will continue in this sphere. Cave ecosystems are, by their very evolution, are stable but are fragile given that the various organisms are adapted to a fairly unchanging set of conditions. Ecosystems with low biomass and species diversity are particularly sensitive to perturbation and additions to the naturally occurring food source can have very large effects on the system (McReynolds 1975). Although we say cave ecosystems are relatively stable, McReynolds points out that they are in "...a tenuous balance that teeters on the brink of doom".

Poulson and Kane (1990) have demonstrated how the introduction of a new food type (horse manure!) changed a deep cave community quite dramatically. Local specialist species were repelled, new species were attracted into the site and previously rare species became dominant the expense of others. As a result a whole new community developed. Glenn Campbell, in his PhD work at Sydney University, discovered that many food scraps were being utilised by cave animals.

May (1971) collected nine species of fungi from North Island, New Zealand, caves. Two of these were growing "on remains of bread mixed with mud". [Kiwi cavers obviously don't eat Mars Bars!] During the Kubla Khan work referred to above three of us sat on the sand bank above where the River Alph sinks and consumed our lunch - three battered Mars Bars. Although we were not aware of having dropped any fragments at all within a few days it became apparent that we has done so. Tiny pieces of the chocolate 'skins' had fallen onto the silt bank - fungi grew upon the chocolate and various species came to feast on the fungi and each other. Whether this had a long term effect in this environment is unlikely but the 'Paradox of Enrichment' is a very real peril to the stability of cave animal communities.

Cavers are a potential effective force for the introduction of plants and animals from one cave or area to another. How many of us launder our overalls and clean our boots between trips - much less than between caves? It is clear that we may be transporting only highly cryptic species but nonetheless it is probably occurring. Derek Ford suggested to APS that the bacteria which may or may not be involved in mondmilch (moonmilk) production are prime candidates for transport and infection of another cave. He went so far as to suggest that this may have happened to Jillabenan Cave at Yarrangobilly.

From time to time one hears suggestions that we could transplant animals or re-populate de-pauperate caves. Vandel (1965) warns against such propositions and a moments reflection will suggest some of the dangers that may be arise. He cites some examples of taxonomic confusion brought about by transplants but Australian cavers would probably be more convinced by the example of the rabbit, the cane toad and the prickly pear.

Changes to the hydrologic regime, both as to quality and quantity, induced by cavers are quite common. These may range from water tracing activities to major diversions such as were propounded at the Tenth ASF Conference in Brisbane. Such activities deserve especial care as we very rarely have any real understanding of cave waters and their biota. Poulson (1975) argues that aquatic cave ecosystems are even more vulnerable than terrestrial cave communities. In a dry continent such as Australia we should be especially careful.

The coal-tar derivative dyes such as fluorescein and rhodamime WT are relatively environmentally inoffensive especially in low concentrations. However, the optical brighteners such as leucophor may be less so. It should be noted here that soaps and detergents - cavers have been known to wash - as well as being pollutants in their own right may act as transport agents for bacteria, viruses and other biological entities for greater distances than would usually occur (McReynolds 1975).

Enlarging or creating entrances or by linking caves at depth may well produce changes in cave microclimate to the detriment of speleothems and other sediments as well as biological systems. Most of our examples of the damage to caves produced by changing cave microclimates come to use from tourist cave areas but there are undoubtedly instances of changed cave environments arising from wild cave digs.

Various examples are recorded in the literature, but the most spectacular from our personal experience is at Dalleys Cave, Murrindal, (Hamilton-Smith 1970). When this cave was first entered, the walls of the lower passages were coated with wet mud which in turn supported a great population of invertebrates. Within a couple of weeks, the walls were dry (and have remained so ever since) while most of the fauna has disappeared. In this case, the cave had obviously always had considerable air circulation, and the digging to gain entry was relatively minor in relation to the cave as a whole; yet the cave climate was changed to a remarkable extent.

Another long-standing example of the impact of digging, together with other impacts, is afforded by Alexandra Cave at Naracoorte, South Australia (admittedly a show cave). This cave was totally sealed and entry was obtained by digging out a depression where water had been seen to soak into the ground. Over many years, the speleothems dried out, became brittle and developed a dry, unattractive surface. Replacing the cave gate of widely space wooden slats with an airtight door quickly restored the surface quality of the decoration. However, it was then found that the entry of people had introduced algae, which led to an explosive growth of lampenflora, some of which has proved difficult to deal with as it had developed on moonmilk (probably also the result of introduced organisms, as it does not appear on the original photographs).

DEALING WITH IMPACTS

There are a range of ways in which we might minimise visitor impacts:

1. Hardening the environment in order to reduce the impact of visitors
2. Decreasing the demand for cave experience
3. Increasing the supply of caves
4. Exporting the demand to other countries
5. Restricting access to caves (rationing)
6. Reducing impacts of visitors

Every one of these has its problems or even contradictions. However, if the evidence of impacts which we have presented above is valid, and we believe it is, then we have a major problem. So, in spite of the problems, we must consider application of at least most of these possible techniques. We now turn to a discussion of ways to minimise impacts.

1. Hardening the environment in order to reduce the impact of visitors.

We are all familiar with this. Every tourist cave does it to at least some extent - often quite excessively. To an extent it works. EHS has recently replicated the first-ever photographs, often taken with a day or two of first entry, of many Australian tourist caves. In most cases, a remarkably complete preservation of speleothems has been achieved. But one only needs to look down at the floor to see massive destruction of layered sediments, fossil materials and nobody knows now what else. Obviously, this could have been avoided and hopefully would be avoided in future developments. That is just a technological application.

The greater problem is the one which leads many recreational cavers to feel uncomfortable or even negative about tourist caves. Geist (1979) puts it far more eloquently than we could:

... technological means to reduce user impact on wildlands increasingly put the individual into a technological cocoon that isolates him from the very wildlands he visits whether he like it or not. He who uses a propane camp stove instead of a campfire loses the knowledge and skills needed to find the proper kindling and wood, know how to coax a fire when the elements conspire against it nor will develop a pioneer's eye for selecting his nightly camp spot ... They rob a person of knowledge, skills and insights.

... does that not defeat and trivialise the very essence of recreation which is adventure and a test of oneself, be nature perceived as an adversary or romantically as a nurturing, supporting mother ? Add to all this the regulations, 'Thou shalt not ...' and the interpretive services that tell you where to look and what to appreciate. Is this the life of kings?

Geist challenges us to think carefully about hardening because it can dilute the quality of our recreational experience; but then so does destruction of the environment. So, we might find a marked trail in a wild cave detracts from the feeling of being in a truly wild environment - but isn't that better than having a calcite floor covered with multitude of muddy footprints?

2. Decreasing the demand for cave experience.

One of the great creators of demand for cave experience was Norbert Casteret's "Ten Years Under the Earth" with its multitude of editions in a multitude of languages. But Casteret has a million imitators in newspapers, magazines, movies and books (and even bumper stickers!).

We are probably all guilty of increasing demand, simply because we are enthusiastic about our chosen activity. But we all know that of the many people to whom we speak, only a few actually join with us in caving. It may only be 1% of those within whom we have discussed caving. But this vanishes into insignificance against .001% of the readers of a really widespread popular magazine, or .01% of the readers of "Australian Geographic".

It is probably impossible to avoid some creation of demand, but perhaps we can focus our publicity upon those most likely to be interested already, or most likely to be environmentally sensitive and responsible.

A particularly disastrous form of demand creation is the habit amongst some enthusiastic cavers of taking such groups as youth clubs, or school parties into caves of high scenic or other values and also high vulnerability. While this may give them a higher quality experience than more robust caves, it means that many of these visitors are likely to return with groups of friends as they now know the location of the cave and are confident that they can find their way. This is the 'vandalism chain' effect described by Barr (1963) - and it still happens! This accounts for at least a large proportion of the 'casual, disorganised' visitors whom we have encountered.

3. Increasing the supply of caves

Theoretically, one might reduce impacts per cave by an increase in supply. In practice, the discovery of further caves only provides a minor increase in supply and so serves to increases the number of significantly impacted sites. Experience over the last 40 years at areas like Buchan, Jenolan and Naracoorte demonstrates this. This is not a useful strategy.

4. Exporting the demand to other countries

Cavers of many countries, including our own, have done just this, but the ones who travel the world to seek new caves are a minority, and many cases, they take undesirable or sometimes quite extreme impacts with them. Again, this is no solution to impact problems.

5. Restricting access to caves (rationing)

One of us has already discussed this at some length (Hamilton-Smith 1983, 1990) drawing upon the important broader work of Stankey and Baden (1977). This paper dismissed four of the key methods - advance booking on first-come-first-served basis, lottery, queuing on site and pricing - as irrelevant or inappropriate to rationing of cave access in Australia.

This leaves us with the allocation of opportunities by merit, and we quote from Hamilton-Smith (1990):

This seems appropriate, because it allocates access to those who most 'deserve' it. In the case of fragile land resources, as caves are, the assumption is that we will ration the resource amongst those who are best able to safeguard its values. The problem is how we might best decide which applicants are likely to safeguard these values. In Australia, it has been general practice to limit caving in some areas to member societies of the Australian Speleological Federation. Personally, I have some doubts about this, not because there is necessarily anything lacking in the competence and sense of responsibility of such groups (although sometimes there may be - it would be foolish to claim perfection) but rather because there is almost certainly equal competence and responsibility in other groups. In other words, a permit system which operates on questionable and arbitrary basis may very well be quite inequitable. So, allocation by merit tends to be unjust. Land managers are forced to either adopt an arbitrary criterion, such as membership of a recognised organisation, or to enter into the very difficult and inevitably subjective task of assessing the merits of each applicant party.

Today the situation is changing. Clearer thinking about the locus of responsibility and accountability of public agencies makes it much more difficult for managers to use organisational membership as a basis for rationing unless it is linked with some sort of formal qualification (as in the Cave Divers Association of Australia). Further, many managers and their staff are now well skilled and experienced in caving techniques and have a well-developed understanding of environmental management. They are now able to move towards making their own judgements about which groups are trustworthy, or demanding evidence of both competence and responsibility on the part of at least party leaders.

It is also possible in the current economic climate that we may have to come to grips with pricing as a possible control over cave access. It has already been suggested in several states of Australia, and although it has been strongly contested on the grounds that cavers are major providers of knowledge to managers, it is probably only a matter of time before caving parties are charged an access fee as in some other parts of the world. Given that most caving parties do no original or additional investigation at all and neglect to submit copies of reports or photographs to managers, we are (as cavers) on truly shaky ground in arguing against the imposition of fees.

Has the time come when organised speleologists should set up training programs for party leaders, open to all interested people - not just their own members ?

6. Reducing impacts of visitors

Essentially, this means changing the behaviour of visitors. Firstly, let us be positive, noting that a great deal has already been done. Cavers not uncommonly remove their boots and muddy overalls in well decorated areas; survey markers are much more unobtrusive; cavers rarely smoke in caves; underground camping has almost disappeared; graffiti is now relatively a rarity; littering has generally disappeared (remember flash bulbs and cubes?); trails are often marked and even if they are not, cavers are more likely to follow existing tracks; carbide lighting is almost dead.

All of this good behaviour may well occur amongst the organised, including both ASF member societies and Scouts. But it is also commonly seen amongst some of the 'casual, disorganised' cavers, many of whom, as we noted in our introduction, are remarkably environmentally responsible.

At least two other issues are worth noting here. One is the issue of repeated visits. Intuitively one caver visiting the same cave 200 times has much the same impact as 200 cavers each visiting once. This is not always the case as repetitive use in short time frames (i.e. many at once) often has a greater direct effect on soil/sediment stability and transport and on animal communities than does a large number of individual impacts. Many impacts in a short time are multiplicative; smaller numbers over a long time seem to produce additive impacts. Ethical questions also need to be considered here. The extreme example is probably the Tasmanian caver who actually brags of the number of times he has visited Kubla Khan! Part of any low-impact ethic would surely be that we will refrain from re-visiting any cave unless there is good reason for doing so. Certainly, there often is good justification for repeated visits to continue exploration, or carry out some other research and study activity - but just going back to the same cave for the pleasure of doing so has to be considered in relation to the level of impacts which result.

The other is the practice in some caves, for example, Scrubby Creek at Buchan and at Yarrangobilly and many other places, of providing in-cave notices which instruct visitors on-site in appropriate minimal impact behaviour. Many well-known examples of destruction, for example, Chevalier at Jenolan and Honeycomb at Murrindal, might have been avoided or at least lessened if this had been done - many destructive impacts result from ignorance or stupidity rather than any wilful and deliberate action.

So, as a practical outcome of all this, perhaps the Federation should, as a matter of urgency, draw up a Low Impact Caving Ethic and make this widely available through member societies, equipment shops, land managers, etc. We use the word 'ethic' deliberately and advisedly. It is not just a matter of a code of behaviour, but rather our total position in relation to our land resources. Such an ethic would draw upon various of the past statements of the Federation and others, integrating these into a single statement with a focus on minimising impacts.

Britton (1975) in a comparison of British and American cave conservation and management practices states that in Great Britain:

In the entire country, no cave now exists which has a man-sized entrance and undisturbed biology or sediments, and the bitter fruit of the early gatings ensures that the reservation of caves which remain to be discovered will be difficult or impossible ...

He goes on to say:

There is little discernible difference between American and British cavers and they will probably react similarly in similar situations. Thus it seems reasonable to expect that, over a period of time, the great bulk of American caves will be gutted of everything fragile by sport caving but that the period of time may be markedly extended if leadership of stature is available ... Much remains undamaged as yet but unless America finds the solutions which eluded the British it will not stay that way.

Australia has a long and positive record of cave conservation and management and one would hope that Britton's gloomy, hopefully overstated, outlook is not to be a model for this country. However, without doubt there is a need for us to build on our record and leave some of Australia's caves and their contents in a relatively untouched condition.

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