Investigation of Potentially Sensitive Plant Communities in the Old Dummy Burn, Kanuti National Wildlife Refuge, Alaska, 2006
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Investigation of Potentially Sensitive Plant Communities in the Old Dummy Burn, Kanuti National Wildlife Refuge, Alaska, 2006 Robert Lipkin Alaska Natural Heritage Program Environment and Natural Resources Institute University of Alaska Anchorage 707 A Street Anchorage, Alaska 99501 December 2007 INTRODUCTION........................................................................................................................................ 2 METHODS.................................................................................................................................................... 2 RESULTS AND DISCUSSION................................................................................................................... 3 COMMUNITIES........................................................................................................................................... 3 FLORISTICS ............................................................................................................................................... 6 RECOMMENDATIONS ............................................................................................................................. 9 ACKNOWLEDGEMENTS ....................................................................................................................... 10 LITERATURE CITED.............................................................................................................................. 10 APPENDIX A: TABLES ........................................................................................................................... 12 APPENDIX B: LIST OF VASCULAR PLANTS COLLECTED FROM THE KANUTI NATIONAL WILDLIFE REFUGE, 13–18 JULY 2006................................................................................................13 APPENDIX C: ALASKA NATURAL HERITAGE PROGRAM CONSERVATION RANK DEFINITIONS FOR SPECIES................................................................................................................. 15 APPENDIX D: FIGURES ......................................................................................................................... 16 1 Introduction The Kanuti Kilolitna River flows west along the southern boundary of the Kanuti National Wildlife Refuge (KNWR) and then turns sharply north through the refuge to join the Kanuti River northwest of Old Dummy Lake. The KNWR has an active wildfire history and the Old Dummy fire of 2005 burned areas adjacent to the Kanuti and Kanuti Kilolitna rivers. During a 1999 survey of the Kanuti Kilolitna River, Saperstein (2007) noted plant associations on gravel bars and adjacent upland sites that were not seen elsewhere in the Kanuti National Wildlife Refuge, including wild carnation (Dianthus repens) and sage (Artemisia spp.). The University of Alaska, Alaska Natural Heritage Program (AKNHP), had been contracted to conduct a post-fire investigation of invasive plants in KNWR and agreed to expand this work to include a preliminary study of these alpine and riparian plant associations, including their statewide and global significance and the potential effects of fire on these associations. This report focuses on the results of the 2006 investigations of these alpine and riparian sites. Methods Fieldwork was conducted between 13-18 July 2006 by Robert Lipkin (AKNHP) and refuge biologist Lisa Saperstein. Gravel bars, river terraces, and alpine slopes with potentially interesting plant assemblages were identified from aerial photography, maps, and the previous experience of Saperstein. These sites were accessed in the course of invasive plant surveys and Composite Burn Index (CBI) surveys conducted in the Refuge at the same time. We based out of KNWR housing in Bettles and accessed individual sites by helicopter. We surveyed the sites on foot, sampling representative habitats and exposures, so as to capture the range of variation at each site. Each site was mapped on an aerial photo or USGS topographic map and a georeferenced point was recorded using a handheld GPS. The routes surveyed were also mapped and representative photos were taken of the sites. At each site we recorded significant landforms and plant associations. A species list was compiled for most sites, with notes on the abundance and habitat for all taxa collected, as well as other taxa present, where possible. Collections were made only if the population was large enough to support removal of individuals following the collecting protocols of Murray and Parker (1990) and Parker and Murray (1992). Rare plant sighting forms with maps were completed for species with an AKNHP state rank of less than 3 (“rare or uncommon,” see Appendix B for discussion of Heritage Program ranks). Each specimen was given a unique collection number tied to a particular date and site, a provisional identification, and dried in plant presses in Bettles. Final determinations were made in Anchorage. The first set of collections will be archived at the Herbarium of the University of Alaska Museum (ALA). A duplicate set, where there is sufficient material, will be housed at the herbarium of the University of Alaska Anchorage (UAA). 2 Results and Discussion Communities Eighteen sites were visited during the 2006 CBI and invasive plant surveys (Table 1, Figure 1). The vegetation of most of KNWR consists of a mosaic of boreal spruce and birch forest intermingled with riparian, palustrine and lacustrine wetlands typical of much of Interior Alaska. Many of the sites visited were characteristic of this boreal forest type, but several (detailed below) represent unusual associations. Two unburned gravel bars along the Kanuti Kilolitna River (sites 141 and 148) contained communities dominated by Artemisia alaskana, Bromopsis pumpellianus, Calamagrostis purpurascens and Dianthus repens (Figure 2). Both communities were on older channels of the river, back from the active point bars, but still subject to seasonal flooding. Both were moist sites, with a very high cover of mosses. In both cases A. alaskana was the dominant vascular plant (> 25% cover), with Dianthus repens and Lupinus arcticus frequent to abundant forbs, and Bromopsis pumpellianus, Calamagrostis purpurascens, Festuca richardsonii, Poa glauca, and Elymus spp. the most common grasses. Although A. alaskana is not uncommon on rubble slopes and (as a minor element) on some gravel bars in Interior and northern Alaska, I have not been able to find any records where it is the dominant member of a riparian gravel bar community, especially not in combination with Dianthus and C. purpurascens. This community is not described in existing vegetation classifications (e.g. Viereck et al. 1992) and discussions with other Alaskan ecologists and botanists have not uncovered similar communities in Alaska or the Yukon Territory. In reviewing Viereck et al. 1992, these communities might represent a variant of an open low scrub Sagebrush-Grass community, II.C.2.n, but differ in being on a gravel bar rather than a steep, south facing bluff, in having a high percentage cover of moss, and in the unusual combination of A. alaskana and Dianthus as dominant species. Other affinities might be with the dry graminoid herbaceous Midgrass-Shrub community, III.A.1.c, but these communities have less than 25% shrub cover, are typically on dry slopes not gravel bars and, again, lack the unusual species combination seen here. These gravel bar communities have elements that suggest they may be analogs of steppe- like grassland communities thought to be more widespread in Alaska during the most recent emergence of the Bering land bridge 8,000 to 20,000 years ago (Young 1982). Young suggests these communities were generally open and characterized by bunch grasses (such as Bromopsis spp. and Calamagrostis purpurascens) and one or more species of Artemisia. Although A. frigida is often seen as a common indicator of modern analogs on south facing bluffs, A. alaskana is likely to have been an important member of such communities on other sites. Both sites (141 and 148) are on the Kanuti Kilolitna River, between the Ray Mountains at the south boundary of the refuge and the confluence with the Kanuti River to the north. A cursory look at satellite imagery of KNWR on Google Earth shows few other gravel bars with similar signatures, and all of them are restricted to this same stretch of the Kanuti Kilolitna River. 3 Flying over the KNWR you are impressed by the extensive stands of mixed spuce and birch boreal forest, interspersed with wetlands, that make up most of the refuge. At the southern edge of the refuge, however, we find a distinctive set of orange colored alpine slopes extending northeast from the northern edge of the Ray Mountains towards Caribou Mountain and the Dalton Highway. These slopes are part of an extensive ultramafic deposit (Patton and Miller 1970) and form one of a series of bands of ultramafic outcrops in Alaska (Patton et al. 1989). The Kanuti series of ultramafics was first mapped by Mendenhall in 1902 during a remarkable traverse by canoe from Fort Yukon to Deering via the Dall, Kanuti, Alatna and Kobuk Rivers. The Kanuti ultramafics were characterized by Patton and Miller (1970) as “typical serpentinites, composed almost entirely of serpentinized peridotites, chiefly harzburgite, and serpentinized dunite. In the field these rocks are recognizable, even at a distance, by their characteristic red-brown weathering and sparse cover of vegetation.” Ultramafic and serpentine soils are well known for supporting unusual