KARST AND CAVE RESOURCE SIGNIFICANCE ASSESSMENT KETCHIKAN AREA, TONGASS NATIONAL FOREST, ALASKA. November 23, 1993 Report of the Karst Resources Panel Thomas Aley, Panel Leader Ozark Underground Laboratory, Protem, MO. Catherine Aley, Panel Member Ozark Underground Laboratory, Protem, MO. William R. Elliott, PhD., Panel Member Research Fellow, Texas Memorial Museum, Univ. of Texas, Austin, TX. Peter W. Huntoon, PhD., Panel Member Professor of Geology, Univ. of Wyoming, Laramie, WY A study and report prepared by the Ozark Underground Laboratory under contract to Ketchikan Area, Tongass National Forest, Federal Building, Ketchikan, Alaska 99901. [This report is a slightly reformatted facsimile of the original.] Educational Field Programs (cid:121) Water and Land Use Investigations in Soluble Rock Terrains (cid:121) Research Facilities and Assistance ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ EXECUTIVE SUMMARY Karst is a three dimensional terrane developed on, and within, a soluble bedrock. At least 700 square miles of the Ketchikan Area of the Tongass National Forest (the “study area”) is karst, and it is likely that the extent of karst will prove to be larger when more detailed geologic mapping is conducted. Karstlands extend from salt water to some of the peaks. Springs, caves, sinkholes, losing streams, and a host of other karst features are abundant and often spectacular. A Karst Resources Panel (“the Panel”) was established under contract to the Forest Service to: (1) assess the significance of the karst, (2) determine the effectiveness of present strategies for protecting karst resources and recommend appropriate changes, and (3) recommend focused resource evaluation goals and research for karst areas. This report documents the results of this work. The climatic, geological, and biological setting of the study area is fundamental to an adequate understanding of the significance of its karst resources. The climate is temperate and maritime. Precipitation is abundant; it may exceed 250 inches a year at some higher altitudes; annual runoff ranges from about 60 to 200 inches a year. The carbonate rocks that comprise these karst areas originated on tropical Pacific islands that were transported by plate tectonic movements to their current locations. There is no other place in the world where tropical limestones have travelled so far, been involved in such an oblique collision with a continent, and ended up emplaced in an archipelago setting at such high latitudes. Finally, karst portions of the study area are found in temperate coniferous rain forests, adjacent to peatlands, and in both subalpine and alpine zones. The diversity of karst resources, features, and cave types present in the study area exhibit unusual breadth. Epikarst is an intensely dissolved veneer of intersecting roofless dissolution-widened fissures, cavities, and tubes dissolved into the surface of the carbonate bedrock. Typical thicknesses of the epikarst zone range from more than 100 feet in recently unglaciated alpine areas to =========================================================== _________________________________- _1_ -_______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ less than 5 feet in recently glaciated low elevation areas. The quality of some of the epikarst in the study area is surpassed only by selected tropical epikarsts in places such as China, Papua New Guinea, and Madagascar; certainly there is no better epikarst in the United States. Vertical shafts and caves are abundant. Some areas have sinkhole densities estimated at 3,000 to 10,000 per square mile. The caves are highly diverse in form and age. Some of them are of great antiquity. Other are intimately associated with up-gradient peatlands. Por- tions of the area contain superb littoral (sea) caves, some of which were formed when massive weights of glacial ice had depressed the land surface relative to sea level. A troglobitic amphipod, Stygobromus quatsinensis, was discovered on Heceta Island (55°45’53”N) during the Panel’s visit. This discovery is a high-latitude Western Hemisphere record for a cave—adapted species. Archeological and paleontological deposits in the area are primarily known from cave and rockshelter sites. Preservation of bone and organic materials is excep- tionally good in these cold environments. To date, significant archeological and paleontological materials have been discovered in at least thirty caves and rock— shelters on seven islands in the study area. Such material is of international importance in tracing the regional prehistory, the effects of climatic changes, and the colonization of the Alexander Archipelago by wildlife and humans at different times in the past. The karstlands of the study area, and the caves within, have enormous recreational values. They offer beauty, discovery, and adventure. The entire Panel was extremely impressed by the exceptional recreational values existing in the karst of the area. It is the conclusion of the Panel that karst resources of the study area possess eight attributes which are of international-scale significance. These are: 1. The occurrence of major karst development in the unique geologic and archipelago setting of Southeast Alaska. 2. The occurrence of significant portions of the karst in a largely undisturbed, high-latitude temperate =========================================================== _________________________________-_ 2_ _-______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ coniferous rain forest. Such settings are, for practical purposes, globally limited to Southeast Alaska. Small amounts of karst in temperate coniferous rain forest remain on Vancouver and Queen Charlotte Islands. 3. The tremendous diversity of karst features present in the study area. 4. The quality of natural preservation of karst resources. 5. The density and degree of development of karst features. 6. The existence of large and extremely well—preserved littoral (sea) caves, some of which are now located at elevations higher than present—day sea level. 7. The presence and abundance of archeological resources which include cave art and may include critically important deposits helping us understand prehistoric colonization of the North American Continent. 8. The existence of outstanding and unique paleon— tological deposits of international significance in understanding climatic changes and their effects. The panel further concludes that karst resources of the study area possess nine attributes of national—scale significance. These are: 1. Regional karst dissolution rates (regional denudation rates) on the order of at least 4 to 8 times greater than rates in most other American karst areas. 2. Abundant and unique moonmilk deposits. 3. Intimate relationship between peatlands and vertical shaft development in adjacent down—slope car- bonate rocks. 4. Contribution of runoff water to some of the most significant fisheries streams in the study area; it is probable that streams draining karst areas have appre- ciably greater aquatic productivity than streams draining nonkarst areas. The fisheries resources of streams in the study area are clearly of national significance. 5. Troglobitic (cave—adapted) invertebrates on inner islands (such as Prince of Wales) are either very rare or absent; such species are found on outer islands (such as =========================================================== _________________________________-_ 3_ _-______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ Heceta and Dali). This difference is probably attributable to differences in the extent of recent glaciation. 6. Discovery of a troglobitic cave amphipod, Sty- gobromus quatsinensis, in a cave on Heceta Island. 7. Cave use by large mammals to an extent no longer seen in the “Lower 48 States”. 8. The unique opportunity to study evolution and adaptation of invertebrates in an archipelago setting with a complex geologic and glacial history. 9. The recreational potential of vast and largely untouched and unexplored caves and cave passages beneath “the last frontier” of Alaska. Karst systems impose major land management liabilities not encountered in nonkarst areas. The subsurface karst drainage networks generally operate independently of, and with more complexity than, the surface drainage systems above them. Three important considerations apply. First, the size and shape of the karst systems often have little or no relationship to the overlying surface drainage systems. Second, the direction of flow through the karst systems often cannot be predicted from surface topography or geologic mapping. Third, the discharge from a karstic groundwater system is not always localized at one spot as occurs in a surface drainage basin. Water entering one sinkhole in a basin may discharge from several springs at diverse compass bearings from the input sinkhole. Flow velocities in the groundwater system often equal or approach surface stream velocities. Pollutants such as diesel fuels or fine sediments from roads or other dis- turbed lands can arrive unexpectedly at one or more distant springs within hours to a few days. Human water supplies and fisheries are routinely, and severely, impacted by such events in karst areas. In nonkarst portions of the study area sediment must move laterally to a stream, and then flow down the stream. Management efforts are made to protect riparian corridors from logging and its impacts. The large amounts of slash and cull materials remaining on the ground after logging, plus the heavy moss growths on the ground prior to logging, help trap and retain substantial amounts of the sediment. Vegetation can rapidly become established on trapped sediments. =========================================================== _________________________________-_ 4_ _-______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ Karst areas transport sediment differently from nonkarst areas. In karst, much of the sediment must move laterally for only a few feet before it is directly transported downward into conduit portions of the karst groundwater system. Once sediment is in the conduits there are no effective natural processes for trapping and retaining it within the system; as a result, it is delivered to a receiving spring or stream. As demonstrated by the dye—tracing work conducted by the Panel, the receiving spring or stream may be several thousand feet away from the point of sediment introduction. Areas with deep and well—developed epikarst have more closely spaced near—surface openings into which sediments can be flushed than is the case in areas with only shallow epikarst. As a result, sediment transport potential is typically much greater in areas underlain by deep and well-developed epikarst. Observations by this Panel indicate that most of the thin epikarst occurs in areas at relatively low elevations on the inner islands. These are also areas with typically less rugged relief. Much of the remaining virgin forest on karst is underlain by deep and well-developed epikarst and is characterized by steeper slopes. When timber harvest and road construction occur on well—developed epikarst with steep slopes, sediment transport and erosion problems will be substantially greater than on the thin epikarst and lower relief lands. The importance of cave resources has been recognized by the Forest Service in the study area since 1988. This recognition, and the enactment of the Federal Cave Resources Protection Act in 1988, led to cave inventory work and ultimately to the development of standards and guidelines. These contain laudable features and in some cases provide adequate protection for cave features. Cases where adequate cave protection occurs typically have both of the following characteristics: 1. The block of forest in which the cave entrance is located has not been logged or roaded and the cave is far enough from clearcut areas that accelerated windthrow of trees does not reach to areas close enough to the cave =========================================================== _________________________________-_ 5_ _-______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ entrance to alter entrance microclimate. 2. None of the area which contributes water to the cave is affected by logging or road construction. Cases where implementation of the existing standards and guidelines has not provided adequate protection for cave features typically have some or all of the following characteristics: 1. The area around the cave entrance has been logged and no buffer zone, or else only a narrow buffer zone, of uncut trees was left around the entrance. Windthrow of trees, when they are left in small, isolated patches, is excessive and appears to almost always occur. 2. Roads, quarries, or clearcuts were located in areas which contribute waters to the cave. 3. Caves were not discovered early enough to modify the cutting area and/or road construction. We have identified six short comings of present cave resource protection actions in the study area. They are: 1. The level of effort expended in reconnaissance work to locate and assess caves has been inadequate. This is to be expected in a fairly new program. 2. Insufficient time between reconnaissance work to locate and assess caves and the start of road construction or timber harvest activities. This results in last minute surprises and band—aid—mitigation efforts instead of sound resource management. 3. Inadequate recognition of the adverse impacts of roads on cave resources. 4. Inadequate recognition of the adverse impacts of quarries on cave resources. 5. Typical cave resource protection in the study area has focused almost exclusively on those caves reached through humanly accessible cave entrances. Such humanly accessible caves are only a fraction of the total cave resource. There are karst portions of the study area where surface features clearly demonstrate that caves, and probably very sizeable caves, underlie the area. Such caves are not receiving resource management attention compatible with that provided for caves with open entrances; this is not a desirable resource management =========================================================== _________________________________-_ 6_ _-______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ situation. 6. Cave resource protection actions have focused upon cave features (and particularly cave entrances) rather than upon cave systems. Cave resource protection must shift its focus from feature protection to system pro- tection strategies. A management strategy of recharge area delineation and vulnerability mapping is recommended by the Panel. The recharge area for a cave or spring is the area that contributes water to the cave or spring. In some cases the recharge area is little more than the land that overlies the cave. However, in many cases (and especially when the cave contains streams or lakes) the recharge area may be very large. Groundwater tracing is a fun- damental tool for recharge area delineation. Vulnerability mapping is a land management tool that has been used effectively in a number of karst areas. It utilizes the fact that some lands in a karst area create appreciably greater groundwater contamination risks than other lands. Recharge area delineation, in concert with vulnerability mapping, is appropriate and necessary for sound land management in the karst of the study area. Such delineation and mapping will help insure that land use and land management actions in karst portions of the study area are appropriately tailored to site conditions. Features and conditions that should be incorporated into a recharge area delineation and vulnerability mapping strategy are outlined. The Panel reached 12 summary conclusions: 1. The karst and caves of the study area have attributes of international—scale significance. 2. The karst and caves of the study area have attributes of national—scale significance. 3. Significant karst resources are likely to extend into other areas of the Tongass National Forest. 4. Karst attributes of national and international scale significance are being degraded by (1) timber harvesting, (2) road location, construction, and opera- tion, and (3) quarry construction and inadequate closure. 5. Resource management in the study area must be conducted with adequate recognition of the archipelago =========================================================== _________________________________-_ 7_ _-______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ setting of the area and its associated ecosystems. 6. Unique karst-specific conditions require that management of karstiands must follow a different man- agement track from the track appropriate to nonkarst areas. The karst areas should be thought of, and managed, as islands within islands. 7. The Panel is concerned about reforestation con- ditions that commonly occur on the karstiands following timber harvest and that degrade the utility and/or the utilization of karst resources. 8. Karstiands are of critical importance to the fisheries of the area. Maintenance of long term high productivity in these streams will be a major benefit from improved karstiand management. 9. Cave resource protection actions by the Forest Service have been laudable, but have commonly not provided adequate protection for cave features. 10. Management of karstlands should involve four key components: (A) inventories of karst features, (B) recharge area delineations, (C) vulnerability mapping, and (D) incorporation of results from items A through C into planning and land management decisions. 11. The Forest Service should identify one or two high-quality, but minimally-impacted, karst areas for possible designation as a Research Natural Area. 12. Ten future study topics have been identified and prioritized. Concurrent efforts on multiple items will probably be superior to placing all effort on a single item. Top priority should be given to: A) Protection and study of archeological and paleonto— logical deposits because they are fragile and irre- placeable. B) Testing and implementation of the outlined approach for recharge area delineations and related vulnerability mapping. C) Cave resource inventories and mitigation assessments should be expanded and enhanced to ultimately insure that they are reflective of the entire range of karst resources. D) Karst resources on other areas of the Tongass National =========================================================== _________________________________-_ 8_ _-______________________________ ____________________________________________________________ Ozark Underground Tongass N.F. Laboratory Karst Resources ============================================================ Forest are largely unknown and may be of comparable, and potentially complimentary, significance to those now known in the Ketchikan Area; they should be assessed. It is only very recently that the Forest Service has begun to recognize the significance of karst resources in the study area. With this ever-growing recognition of significance has come awareness of resource vulner- ability. This recognition and awareness led to the work of this Panel. Our Panel’s conclusions have clearly demonstrated that the karst resources of the study area are of tremendous national and international significance for a substantial number of reasons. We have also dem- onstrated that many of these unique and priceless resources are also highly vulnerable to resource damage. The challenge facing the Forest Service is to integrate management of karstlands into general land management. The Forest Service must adequately protect and utilize the host of newly—recognized resources and resource interactions; recognizing new resources does not mean forgetting older resources. The Forest Service goal must be ecologically sound and scientifically credible resource management of the karstlands of the study area. =========================================================== _________________________________-_ 9_ _-______________________________