3087 HOSKINS ROAD
NORTH VANCOUVER, B.C.
V7J 3B5
SUBMITTED TO
MR. CHARLIE WESTERN
REGIONAL RECREATION OFFICER
VANCOUVER FOREST REGION
2100 LABIEUX ROAD
NANAIMO, B.C.
V9T 6E9
JANUARY 1995
The following report documents the current information pertaining to the management of forested Cave/Karst ecosystems. Only recently, since the late 1980's, have unique and potentially significant karst resources in B.C. been recognized by the Recreation Branch of the Forest Service. This recognition has come as a result of efforts of the B.C. Speleological Federation and work conducted, mostly in Alaska, by the U. S. Forest Service.
The discussion focuses on the unique geologic, hydrologic, biological, cultural, and recreational attributes of Karst resources and the sensitivity of these systems to development . In general, land management activities can lead to sedimentation, contamination, flooding, and subsidence of the karst ground water basins.
The potential impact of forest management operations on karst/cave resources are dependent on a number of factors. These include the sensitivity of the karst area, method of harvest, quantity and quality of constructed roads, and the associated ecological attributes of the site.
The difficulties entailed in the management of karst resources are compounded by limited management experience of land managers in B.C. Karst resources occupy only a small portion of the land base when compared with other geologic formations. Since 1987 the U.S. Forest Service, in Alaska, has greatly expanded efforts to map and identify cave and karst resources threatened by proposed timber harvesting. The U.S. Forest Service approach is conducted using recharge area delineation combined with vulnerability mapping. Recharge delineation is carried out by ground water tracing. Vulnerability mapping (sometimes called hazard mapping) is four stage process involving;
The review of the literature demonstrates that in B.C., we clearly lack an understanding of existing karst resources. Traditionally, protection of karst resources have been focused on caves and access to caves. This should be considered inadequate as these efforts may have dramatically underestimated the biological, geohydrological and cultural importance of the resource.
It is recommended that the Ministry of Forests investigate some of the issues identified in this paper by:
This report has been prepared in response to a request by Charlie Western, Regional Recreation Officer - Ministry of Forests, Vancouver Forest Region. The following report summarizes all available information which pertains to the management of forested Cave/Karst ecosystems.
Karst is a three dimensional terrain developed on, and within, a soluble bedrock (Aley et al. 1993). Only recently, since the late 1980's, have unique and potentially significant karst resources in B.C. been recognized by the Recreation Branch of the Forest Service. This recognition has come as a result of efforts of the B.C. Speleological Federation and work conducted, mostly in Alaska, by the U.S. Forest Service. The focus within B.C. has been concentrated on protection and management for recreation purposes. Limited work has been conducted which emphasizes the significance of karst geology, hydrogeology, biology, and cultural aspects of the resource. All of these characteristics of karst systems must be recognized if they are to be properly managed within forest land management objectives of the Province.
In British Columbia more than 750 caves, predominantly on Vancouver Island, have been explored and documented (Runka 1992). This represents only a fraction of the potential number of caves and significant karst lands present in the Province. The Karst area of Northern Vancouver Island, which represents the largest proportion of carbonate rocks present on the Island, occurs on the Quatsino Formation as a very uniform, micritic deep-water limestone that is up to 600 m in thickness.
If compared with Alaska, the cave/karst resources of B.C. are a unique, nonrenewable resource with potentially national and international scale attributes. Significant attributes associated with karst resources which have been identified in the literature and may pertain to B.C. include:
To protect these unique and fragile karst resources mitigation strategies have been developed within Canada and the U.S. However, recent U.S. studies have demonstrated that in many cases these strategies have been inadequate and have failed to protect the integrity of the karst ecosystem.
The intent of this paper is to document and describe current cave/karst management strategies as they relate to forest harvesting, and the role of temperate rain forests on cave/karst processes.
Baichtal (1993) has described the karst landscape as an ecological unit found atop carbonate bedrock on which karst has developed and the recharge areas on adjacent noncarbonate substrate. Important characteristics of this ecological unit include: well developed forest communities, productive plant and animal communities, highly productive aquatic communities, extensive subsurface drainage networks, and significant and unique cave resources. A description of the karst resource includes a discussion of geological, hydrological, biological processes and natural history associated with these landscapes.
The term "karst" as it is understood today is generally taken to define or designate one distinctive type of geomorphic and hydrogeologic system that is associated with particularly soluble rocks (Gams 1993). Compared with other hydrogeologic systems Karst has two unique features (Aley et al. 1993). Firstly, the permeable nature of the karst facilitates the circulation of fluids in the down-gradient direction. This feature is absent in most other hydrogeologic settings. The second distinguishing feature of karst landscapes is the organization and hierarchy of the collector structures and permeability pathways which are created by the hydrologic circulation system (Aley et al. 1993).
Geologic features which are generally considered significant when assessing the diversity of karst areas include epikarst, shafts, sinkholes, sinking streams and caves. The epikarst can be described as an intensely dissolved veneer consisting of an intricate network of intersecting roofless dissolution-widened fissures, cavities and tubes dissolved into the surface of the carbonate bedrock. Within the literature reviewed there is very limited discussion describing the epikarst present in the carbonate rocks of B.C. Yet in Alaska the epikarst within the Tongass National Forest has been characterized as of a quality only surpassed by selected epikarsts in places such as China, Papua New Guinea and Madagascar.
The hydrogeology of cave and karst landscapes make these areas hydrologically significant (Quinlan 1989). Many cave systems have been found to be hydrologically active, and those that do carry streams are subject to extreme variations in flow (Aley et al. 1993). These systems are capable of transporting sediment, organic material, and even rocks through karst groundwater systems. Transport of water can occur over several thousand feet to receiving caves, springs, and surface streams. Cave/karst water courses have virtually no ability to treat water-borne contaminants, instead they merely transmit contaminant, much as a sewer pipe would (Ford and Williams 1989).
Hydrologic models used for estimating the cumulative effects of proposed surface management activities are not designed to model the effects of timber harvest on the karst landscapes (Baichtal 1993). Evidence, from around the world, suggests that timber harvesting increases surface runoff, thereby accelerating erosion, sediment production and debris transport which in turn results in flooding of karst passages which have not flooded for long periods of time (Baichtal 1993, Harding and Ford 1993, Huntoon 1992, Gams 1993, Kiernan unknown)
Few studies have documented the importance of the karst environment to plant and animal life. Limited work in Alaska by the U.S. Forest Service, has begun to investigate the contribution of karst/cave areas to vegetation, wildlife and fisheries.
Forest and Vegetation
The literature identifies a link between forest site productivity and karst. Karst areas are inherently more productive when compared with equivalent sites with nonkarst bedrock types. Increased productivity can be attributed to nutrient rich soils with higher base saturation and well developed subsurface drainage (Aley et al 1993, Baichtal 1993, Harding and Ford 1993). Review of the literature suggests that site productivity is related to the development of the epikarst. The greater the epikarst development the greater the surface /subsurface connection which provides vertical nutrient transport. Disturbance of forest cover and soils in karst landscapes can reverse the positive flow of nutrients to the surface and result in the vertical migration of nutrients and soil beyond the depth of the rooting zone. Karst systems are productive but fragile (Huntoon, 1992a and b; Streveler andBrakel, 1993).
Various reports and studies have attributed higher rates of harvest in karst versus non-karst forests to the superior tree size and quality of these ecosystems (Aley et al 1993, Baichtal 1993, Steveler and Brakel 1993).
Wildlife
The importance of the cave/karst resources has been poorly studied in B.C. Alaska researchers have found that many wildlife species find the surface karst features and the stable environment and shelter provided within the caves to be valuable habitat (Baichtal 1993). Caves provide important natal den sites for otters, and resting and denning sites for deer, bear, wolves, and small furbearers. Deer are known to rest in the vicinity of caves during both the summer, when air from the caves is cooler, and in winter, when cave entrance air is generally warmer.
Cave systems are critical habitat for bats where they are used for roosting and hibernation. Cave environments provide specific air circulation patterns, temperature profiles, humidity, cave structure, and location relative to feeding sites which bats require (Hill and Smith 1992).
Cave environments provide habitat for a significant number of invertebrate species. During 1992 preliminary studies identified 77 invertebrate species from collections made within several caves (Baichtal 1993). The relationship and importance of cave habitats to invertebrate communities within B.C. are poorly researched and documented. This appears to be a significant oversight, as management of surface resources may have a significant impact on these communities.
Fisheries
Research into the relationship between karst landscape and productivity has been reported by Swanson (1993). The karst landscape influences the quality of aquatic habitat in several ways. The geochemistry associated with karst development contributes to productivity in aquatic environments through its carbonate buffering capacity and carbon input dissolved from the limestone bedrock (Baichtal 1993). According to Baichtal, geochemical inputs to water courses within these landscapes have significant downstream effects on the aquatic food chain and biotic community. Preliminary research in Alaska also suggests that these karst stream systems might be eight to ten times more productive than those associated with non-karst dominated aquatic habitats. The karst dominated aquatic systems appear to support higher biodiversity, have higher growth rates for smolts and resident fish, have less variable temperatures and flow regimes, and contain unique habitat affecting species distribution, abundance, and adaptations (Swanson 1993). Alaskan researchers believe that water courses within karst landscapes have the following connection to fisheries:
Karst systems in Alaska have been associated with Pleistocene paleontology and intimately related archeological sites (Aley et al 1993). The cool, basic and constant temperature environments maintained in caves provides an exceptionally good environment for the preservation of bones and organic material. Within the Tongass National Forest significant archeological and paleontological materials have been discovered in more than thirty caves and rockshelters (Carlson 1993). These materials have been recognized for their significance in reconstructing regional history, climate change, and human colonization by humans and wildlife in the past.
In B.C. the driving force behind karst/cave protection has been from the B.C. Speleological Federation. This small group of organized cavers has been responsible for the exploration and inventory of many of the caves identified to date. They have documented the enormous recreational resource values and potential, and have work tirelessly for improved protection(Pynn 1992).
For reasons discussed previously the higher productivity of these systems generally provides for significant surface and subsurface features of recreational importance. The unique cave karst features present in B.C. have attracted national and international recreational cavers (Scheffer 1993). The Ministry of Forests is currently responsible for the inventory of karst/cave resources in B.C. and to date manages the Candlestick, Upana, and Artlish Caves as recreation sites.
Designation of cave and karst resources as recreation sites offers significant protection status if classed ER l(no harvesting allowed); given the current state of knowledge of these systems, this could be considered adequate. The current state of protection does not adequately represent the karst/cave resource as an ecosystem which must be managed as such. Recreation sites are generally too small to protect these values. This is not entirely the fault of the Ministry of Forests, as only recently has work in Alaska determined the significant geologic and biological interrelationships of these systems.
Unlike other rock formations karst rock types are considered more sensitive to development. In general land management activities can lead to sedimentation, contamination, flooding, and subsidence of karst ground water basins.
Soil development in karst areas often results in thin folisols which contain only small amounts of inorganic matter. These soils are highly susceptible to erosion and sediment transport resulting from high precipitation levels encountered in coastal ecosytems.
The subsurface drainage networks within these systems have been found to operate independently of, and with more complexity than, surface drainage systems on the surface (Aley et al. 1993). Aley et al. 1993 have documented three important considerations in this regard:
The transport of sediments within karst areas is different from non-karst areas. Lateral movement of sediments for only a few feet may result in direct transport downward into conduit portions of the karst groundwater system (Baichtal 1993). Once in the groundwater system there is no natural trapping or retention mechanisms for sediments, resulting in direct input to receiving streams and springs. The depth of the epikarst is also important to the movement of sediments. Areas with deep and well developed epikarst have more closely spaced near-surface openings into which sediments can be flushed. As a result sediment transport is typically much greater in deep well developed epikarst (Aley et al 1993).
The potential impact of forest management operations on karst/cave resources are dependent on a number of factors. These include the sensitivity of the karst area, method of harvest, quantity and quality of constructed roads, and the associated ecological attributes of the site.
The traditional method of harvest in coastal B.C. forests has been clear-cutting. This has been the preferred method for economic as well as ecological reasons. Generally the clear-cut system is seen to be the most efficient and cost effective method to harvest forest trees. It has also been seen as the most effective-way to achieve reforestation objectives. In general, clear-cutting prepares the site for planting and provides a preferred environment for the management of desirable tree species. In B.C. the decision to clearcut is based on knowledge of management objectives, the ecological characteristics of the ecosystems, stand characteristics,and the climatic conditions conducive to successful regeneration (Klinka et al. 1990). However, clear-cutting is like any silvicultural treatment, a useful technique when applied in the right manner, at the right time, in the right place, and for the right reason (Kimmins 1977).
The practice of clear-cutting has often has often been associated with the degradation of karst/cave resources in B.C. and other parts of the world. This is mainly a function of the removal of forest cover and the associated increased surface runoff, sedimentation and woody debris which easily moves through karst systems and impacts significantly on the hydrogeologic, biological and recreational characteristics of the karst resource. In addition, the clear-cut harvest method has also been responsible for:
The quantity and quality of roads constructed for harvesting are also critical in their potential impact on karst resources. Poor road building techniques which result in increased sedimentation, soil surface erosion, collapse of interconnecting caves and tunnels may lead to serious reductions in the quality of the karst resource. In general, road construction has the potential to impact on habitat of cave dwelling organisms, subsurface water quality and flow rates, interconnected surface/subsurface springs and streams, and fish habitat.
The density of constructed roads both for permanent access and those used specifically for harvesting may also significantly impact karst areas. This will be influenced by the type of equipment used. Ground based skidders, hoe chucking, and grapple yarding have the potential to significantly increase the area of soil disturbance and site degradation when compared with cable harvest systems.
The unique and sensitive ecological characteristics of karst/cave sites have already been discussed in previous sections. In addition to previous sections, negative impacts on karst systems will be further aggravated on steep slopes which exceed 70% (Harza Northwest Inc. 1994). These authors reported slopes exceeding 70% require protection because of soil erosion and forest regeneration considerations.
The difficulties entailed in the management of karst resources are compounded by limited management experience of land managers in B.C.. Karst resources occupy only a small portion of the land base when compared with other geologic formations. In fact, within the literature reviewed, figures on the exact percent of Karst area on Vancouver Island and within B.C. have not published. The small area represented by karst is not unique to the Province. For example, in the Australian state of Tasmania, carbonate rocks represent about 4% of the land surface (Kiernan unknown). While in Alaska, Ketchikan area karst landscapes represent approximately 11% (Baichtal 1993). The largest reported proportion of karst rock types are found within China, where they represent 33% of the landscape (Kiernan unknown ).
Since 1987 the U.S. Forest Service, in Alaska, has greatly expanded efforts to map and identify cave and karst resources threatened by proposed timber harvesting. Initially mitigation strategies were developed to protect caves from the effects of timber harvest (Baichtal 1993). These initial protection efforts were focused on protection of karst feature preservation. The early strategies developed were inadequate as many of the timber reserves set aside to protect karst resources blew down causing extensive degradation. Mitigation was successful only in those situations where buffer areas were large enough to insulate karst resource features from the effects of micro-climate change, road building, and windthrow.
U.S. Forest Service land managers began to realize that karst resource protection was based on an understanding of karst system function, and the management of these areas as ecological units. Their research indicated that the success of protection efforts was a function of the maintenance of surrounding forest integrity and that the "recharge area" was not affected by harvesting and road building activities. The "recharge area" was defined as an area contributing to water sources of a cave or spring. This area varies in size and may be very small, representing only the land which overlies a cave, or may be very large in areas where caves have significant streams or lakes. In addition, work by Aley et al.(1993) identified some additional shortcomings of the karst resource protection program which included;
Recharge delineation is carried out by ground water tracing. Ground water tracing is conducted by introducing fluorescent tracer dyes at water entry points in the karst system. Suspected water courses (including springs, caves and other relevant points) which flow from within the groundwater of the karst area are then sampled for these dyes.
"Vulnerability mapping" (sometimes called hazard area mapping) has been described as a management tool which has been effectively used in a number of karst areas (Aley and Aley 1993). The following steps outline the procedure to conduct vulnerability mapping as described by Aley and Aley 1993.
The first step is to separate areas of carbonate and non-carbonate geology. The recommended vulnerability mapping should be applied only to carbonate rock areas or areas which contribute water to carbonate rock areas.
The second step in the process is to delineate important features through inventory methods. These features would include, but are not necessarily limited to, the following:
The fourth step in the process is to delineate the area under investigation into various vulnerability classes. Most karst areas in Alaska have been identified as one of four categories: low, moderate, high, and extremely high vulnerability to resource degradation.
In reviewing the literature it is apparent that in B.C. we clearly lack an understanding of existing karst resources. Traditionally, protection of karst resources have been focused on caves and access to caves. This should be considered inadequate as these efforts may have dramatically underestimated the biological, geohydrological and cultural importance of the resource. The current inventory and protection status provided to these karst resources demonstrates a fundamental lack of understanding about the function and ecological sensitivity of these areas and related impacts on other resources.
This same problem has only very recently been recognized in the U.S. and land management strategies have been adjusted to deal with current program inadequacies. The recent evolution of karst management in the U.S. has included assessment of the significance of the resource, evaluation of existing protection and mitigation strategies, and development and refinement of cave/karst protection using more intensive inventory, recharge delineation and vulnerability mapping methods to reduce the impacts of timber harvesting on these resources.
In B.C., we are just now beginning to update inventory information on the location of caves and cave entrances. However, this inventory work may not provide enough detail to adequately address all of the issues discussed previously. The work to date has poorly linked the significance of the cave/karst environment to water quality, fisheries, and wildlife habitat and primarily focused on recreational significance of these resources.
Management strategies need to be developed which recognize all karst/cave characteristics and provide the necessary safe guards to protect these environments. With the advent of the Forest Practices Code and the emphasis on wildlife, fisheries and other resource protection it could be considered a major oversight if these resources were impacted negatively by poor cave/karst management.
It is recommended that the Ministry of Forests investigate some of the issues identified in this paper by:
Definitions from the United States Department of Agriculture, Forest Service, Tongass National Forest Ketchikan Area.
Aley, T. and C. Aley. 1993. Delineation and hazard area mapping of areas contributing water sot significant caves. In: D.L. Foster (ed.): Proc. Natl. Cave Mgmt. Symp., 1991. Amer. Cave Conserv. Assn. pp. 116-122.
Aley. T., C. Aley, W.R Elliott, and P. Huntoon. 1993. Karst and Cave Resource Significance Assessment Ketchikan area, Tongass National Forest, Alaska. Final Report, prepared for Ketchikan Area of the Tongass National Forest. 79 pp. and appendix.
Baichtal, J.F. 1993. Evolution of Karst Management on the Ketchikan Area of the Tongass National Forest: Development of an Ecologically Sound Approach, In: Proc. Natl. Cave Mgmt. Symp., 1993. Ama. Cave Conserv. Assoc. In Press., 14 pp.
Carlson, R. 1993. Overview of archaeological resources associated with caves and rockshelters in southern southeastern Alaska. Alaska Anthropological Assoc., 20 th annual meeting. 12 p. Ford, D.C. and Williams, P.W. 1989. Karst Geomorphology and Hydrology. London, Unwin Hyman, 601 p.
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Hill, J.E., and J.D. Smith 1992. Bats- A Natural History. University of Texas Press. Austin, TX 243 pp.
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Kimmins, H. 1977. On the need for ecological classification of forests. Pp. i-iv in G.A. Drew and J.P. Kimmins, editors. Ecological classification of forest land in Canada and northwestern U.S.A. Vancouver, B.C.: Center for Continuing Education, University of British Columbia.
Klinka, K., R.E. Carter, and M.C. Feller. 1990. Cutting old-growth forests in British Columbia: Ecological considerations for forest regeneration. Northwest Environmental Journal. 6:221-242.
Pynn, L. 1992. Written in Stone. Equinox 65:73-80.
Quinlan, J.F. 1989. Ground-water monitoring in karst terranes: recommended protocol and implicit assumptions. U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory, Las Vegas, Nev. EPA1600/X-89/050 88 p.
Rubin, P.A. 1991. Land use planning and watershed protection in karst terranes. Third Conference on Hydrogeology, Ecology, Monitoring, and Management of Ground Water in Karst Terranes. Nashville, Tenn., Proceedings. National Ground Water Association, Dublin, Ohio. 635 p.
Runka, G. 1992. Stewardship of cave and karst resources in B.C.- a review of legislation, policy and management. Contract report to the Recreation Branch, B.C. Ministry of Forests. 148 p.
Scheffer, J. 1993. Industrial forest operations and their effects on the cave and karst resources of Vancouver Island. Report prepared for the Ministry of Forests, Recreation Branch. 22 pp.
Streveler, G. and J. Brakel. 1993. Cave lands of Southeast Alaska; an imperiled resource. A report to the Southeast Alaska Conservation Council by Icy Strait Environmental Services, Gustavuws, AK. 39 p. + appendix and materials.
Swanson, D. 1993. Preliminary report on current research into stream productivity of karst versus non-karst dominated streams. Research Geologist, Forestry Sciences Lab., Juneau AK.