The distribution and abundance of the endemic vascular plant taxa of the Athabasca Sand Dunes of northern Saskatchewan Eric G. Lamb, Jenalee Mischkolz, and Digit Guedo Department of Plant Sciences, University of Saskatchewan March 2011 Corresponding Author: Dr. Eric Lamb Assistant Professor, Department of Plant Sciences, University of Saskatchewan 51 Campus Dr. Saskatoon, SK S7N 5A8 306-966-1799 [email protected] 2 Lamb et al. 2011. Athabasca Endemics Occupancy Survey Executive Summary An extensive occupancy survey of the Athabasca Sand Dunes endemic flora was conducted in 2009 and 2010. This report is a summary of the findings of that survey. The Athabasca sand dune region is of high conservation value due to the presence of ten endemic vascular plant taxa. These endemics include two composites: Achillea millefolium var. megacephala and Tanacetum huronense var. floccosum, one grass: Deschampsia mackenzieana, four willows: Salix brachycarpa var. psammophila, Salix silicicola, Salix turnorii, and Salix tyrrellii, one pink: Stellaria arenicola and one leadwort: Armeria maritima ssp. interior All of these taxa have been assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). All of the Athabasca endemics are listed under the Species at Risk Act (SARA) as “Species of Special Concern” with the exceptions of Salix tyrrellii and Stellaria arenicola (Not at Risk) and Lechea intermedia (not listed). The 2009 and 2010 occupancy surveys were initiated to provide baseline data on the endemic populations and to provide data for potential status reassessment. Eighty-three prelocated 250m transects were surveyed in the Cantara Lake, Thompson Bay, and William River dune fields in 2009 and 141 prelocated transects were surveyed in the Thompson Bay, William River, MacFarlane River and Archibald lake dune fields in 2010. Extensive populations of Deschampsia mackenzieana, Salix brachycarpa, Salix silicicola, Salix turnorii, Salix tyrrellii, Stellaria arenicola, and Tanacetum huronense were encountered. Very limited populations of Achillea millefolium and Armeria maritima were surveyed, and no individuals of Lechea intermedia were found. Details of the habitat affinities, relative abundance, and community patterns of these species are presented in this report. Key findings of this study with respect to each endemic species include: Achillea millefolium var. megacephala 1) Present in very low abundance in the dune fields with only 592 individuals recorded in survey transects. Patchily distributed in the Cantara Lake, Thompson Bay, and William River dune fields and absent from the Archibald Lake and MacFarlane River fields. 2) Achillea was most frequently encountered and most abundant in wet interdune slacks, which clearly represent the critical habitat for this species. 3) Achillea’s very small population size and limited distribution is cause for significant concern. Armeria maritima ssp. interior 1) The least abundant endemic species observed during the occupancy survey with only 272 individuals identified. Armeria maritima was concentrated in the northeastern sector of the William River dune field, patchily distributed in the Thompson Bay and MacFarlane River fields, and was absent from the Archibald lake field. 2) Armeria was most frequently encountered in gravel pavement habitats with most other observations occurring in low slope Gravel pavements appear to be the critical habitat for this species. 3. Armeria’s very small population sizes, physically vulnerable growth form, and preferred habitat make this species of significant concern. In particular this species’ germination habit on sandy substrates stabilized by gravel pavements likely makes seedlings vulnerable mortality if acid precipitation impairs root growth. 3 Lamb et al. 2011. Athabasca Endemics Occupancy Survey Deschampsia mackenzieana 1. One of the most widely distributed and frequently encountered endemic species in this study, present in all habitat types, and sectors of the dune fields. Flowering individuals and seedlings of Deschampsia mackenzieana were frequently encountered. 2. The wide distribution of Deschampsia within the dune environment suggests that the Athabasca sand dunes as a whole should be considered critical habitat for this species. No obvious threats to Deschampsia mackenzieana populations were noted during this survey. The robust populations suggest that continued efforts to minimize human impacts on the sand dune environment should ensure the continued healthy population size of this species. 3. Deschampsia is extremely common in unstable surface environments, suggesting that it is likely to be minimally affected by surface disturbance (i.e. ATVs.) The open sand germination environment is potentially vulnerable acid deposition, as an impairment of root growth could likely lead to substantial seedling mortality. Lechea intermedia var. depauperata 1) No individuals of Lechea intermedia were observed during this study, even at sites where herbarium specimens had been previously collected. It is important to note, however, that Lechea is primarily found in habitats distinct from the other endemics, and thus survey efforts in potential Lechea habitats were limited. 2) Efforts to resolve the data deficiency for Lechea intermedia should be a priority. Salix brachycarpa var. psammophila 1) Commonly encountered in dune slack habitats, widely distributed in the Thompson Bay dune field and common around the margins of the William River, MacFarlane River, and Archibald Lake dune fields. 2) The concentration of Salix brachycarpa in wet dune slacks suggests that that habitat should likely be designated critical habitat for the species. No obvious threats to Salix brachycarpa populations were identified, however as with many of the other endemic species the concentration of the population in the dune slacks represents a potential limiting factor for this species. Salix silicicola 1) Frequently encountered in all habitats except gravel pavements and woodlands. Salix silicicola was widely distributed in the Thompson Bay and MacFarlane River dune fields and common around the margins of the William River and Archibald Lake dune fields. 2) The wide distribution of S. silicicola within the dune environment suggests that the Athabasca sand dunes as a whole should be considered critical habitat for this species. The distribution of S. silicicola populations suggests that the species primarily germinates and establishes in wet interdune slacks, with mature individuals persisting as large clumps in other habitats following the burial of old slacks by moving sand. 3) No obvious threats to Salix silicicola populations were identified. The robust populations suggest that continued efforts to minimize human impacts on the sand dune environment should ensure the continued healthy population size of this species. 4 Lamb et al. 2011. Athabasca Endemics Occupancy Survey Salix turnorii 1) Frequently encountered in all habitats except lichen-crowberry heaths and woodland. Salix turnorii was widely distributed in the Thompson Bay and MacFarlane River dune fields, common around the margins of the William River dune field, but present only on beaches at the margin of the Archibald Lake dune field. 2) The wide distribution of S. turnorii within the dune environment suggests that the Athabasca sand dunes as a whole should be considered critical habitat for this species. As with S. silicicola and S. tyrrellii the distribution of S. turnorii is consistent with a species that primarily germinates and establishes in wet interdune slacks, with mature individuals persisting as large clumps in other habitats following the burial of old slacks by moving sand. 3) No obvious threats to Salix turnorii populations were observed in these surveys. The robust populations suggest that continued efforts to minimize human impacts on the sand dune environment should ensure the continued healthy population size of this species. Salix tyrrellii 1. Frequently encountered in lichen-crowberry heath, wet interdune slack, and woodland habitats, less commonly encountered in low and high slope dunes and saline slacks, and least frequent on gravel pavements. Salix tyrrellii was widely distributed in all of the dune fields. 2. The wide distribution of S. tyrrellii within the dune environment suggests that the Athabasca sand dunes as a whole should be considered critical habitat for this species. As with S. silicicola and S. turnorii the distribution of S. tyrrellii is consistent with a species that primarily germinates and establishes in wet interdune slacks, with mature individuals persisting as large clumps in other habitats following the burial of old slacks by moving sand. 3. No obvious threats to Salix tyrrellii populations were observed in these surveys. The robust populations suggest that continued efforts to minimize human impacts on the sand dune environment should ensure the continued healthy population size of this species. Stellaria arenicola 1. Frequently encountered in wet and saline interdune slacks and high slope dunes, less frequent in low slope dunes, and least frequent in lichen heaths, gravel pavements, and woodlands. Stellaria arenicola was widely distributed in the Thompson Bay and MacFarlane River dune fields and common around the margins of the William River and Archibald Lake dune fields. 2. The wide distribution of S. tyrrellii within the dune environment suggests that the Athabasca sand dunes as a whole should be considered critical habitat for this species. 3. No obvious threats to Stellaria arenicola populations were observed. The robust populations suggest that continued efforts to minimize human impacts on the sand dune environment should ensure the continued healthy population size of this species. 4. Stellaria is common in unstable surface environments, suggesting that it is likely to be minimally affected by surface disturbance (i.e. ATVs.) The open sand germination environment is potentially vulnerable acid deposition, as an impairment of root growth could likely lead to substantial seedling mortality. Tanacetum huronense var. floccosum 1. Most frequently encountered in high slope dunes and interdune slacks. Tanacetum huronense was widely distributed in all of the dune fields. 2. The wide distribution of Tanacetum huronense within the dune environment suggests that the Athabasca sand dunes as a whole should be considered critical habitat for this species. As with S. silicicola and S. turnorii the distribution of T. huronense is consistent with a species that 5 Lamb et al. 2011. Athabasca Endemics Occupancy Survey primarily germinates and establishes in wet interdune slacks, with mature individuals persisting as large clumps in other habitats following the burial of old slacks by moving sand. 3. No obvious threats to Tanacetum huronense populations were observed in this survey. Flowering individuals were frequently encountered, as were seedlings and juvenile plants in wet interdune slacks. The robust populations suggest that continued efforts to minimize human impacts on the sand dune environment should ensure the continued healthy population size of this species. The present survey covered all of the major sand dune complexes within the Athabasca Sand Dunes Provincial Park. Consistent transect coverage was achieved and this survey thus provides a comprehensive picture of the current distribution and abundance of the Athabasca endemics. Future research should be largely focused on narrower questions linked to the conservation of particular species. The following should be considered priorities for future research: 1. Acid deposition represents the most likely short to medium term threat to the Athabasca endemic species. This threat is likely most acute for species including Armeria maritima, Deschampsia mackenzieana, and Stellaria arenicola that frequently germinate and establish on open sand. Investigations are needed to evaluate the germination ecology of these species and the potential threat that acid deposition may pose to the future viability of these populations. This research is most urgent for Armeria maritima given the low population sizes and non-clonal habit of that species. 2. A general effort to understand how climate changes in the Athabasca region are likely to result in long-term trends toward dune stabilization and related changes in the dune environment is important for the conservation of all of the Athabasca endemic species. Of particular importance are investigations of the ecology and hydrology of wet dune slacks, an important habitat for all of the endemics and critical habitat for Achillea millefolium and Salix brachycarpa. 3. Investigations into the seed and seedling ecology of all of the Athabasca endemic species as it is likely that the seedling life stage and regeneration niche is a primary determinant of adult population sizes, particularly for long-lived clonal species such as the willows and Tanacetum. Understanding species’ life histories is particularly important for Achillea millefolium and Armeria maritima, given their low population sizes. 4. A general landscape classification of the Athabasca Sand Dunes region with particular emphasis on delineating gravel pavements and wet dune slacks. Such a classification would provide a strong tool to identify the extent of critical habitat for many of the Athabasca endemic species. 5. The continued lack of data on Lechea intermedia is of immediate concern and a barrier to any objective status reassessment. Extended surveys of potential habitat for this species should be considered. The data presented in this report represent the most comprehensive survey conducted to date on the Athabasca endemic populations. These data represent a strong foundation for a status reassessment for all of these species with the exception of Lechea intermedia. Status reassessment to a higher level of concern may be justified given 1) the endemic status of all of these taxa, 2) the limited population sizes and distributions within the dune complex of some taxa, particularly Achillea millefolium, Armeria maritima, and Salix brachycarpa, and 3) potential threats to the dune environment including acid deposition and climate change. 6 Lamb et al. 2011. Athabasca Endemics Occupancy Survey Contents Executive Summary ....................................................................................................................................... 3 Acknowledgements ....................................................................................................................................... 8 Introduction .................................................................................................................................................. 9 Field Survey Methods ................................................................................................................................. 10 Data Handling .............................................................................................................................................. 19 Statistical Analyses ...................................................................................................................................... 19 Summary of Field Observations .................................................................................................................. 20 Field Survey Extent .................................................................................................................................. 20 Relative Abundance of species at risk ..................................................................................................... 22 Distribution of Species at Risk ................................................................................................................. 30 Endemic Populations on Lake Athabasca Beaches ................................................................................. 54 Community Level Patterns ...................................................................................................................... 55 Incidental Observations of Human impact in the Athabasca Sand Dunes ............................................. 58 Incidental Observations of invasive species in the Athabasca Sand Dunes ........................................... 59 Evaluation of transect survey error ............................................................................................................ 59 Summary and conclusions .......................................................................................................................... 64 Achillea millefolium ................................................................................................................................. 64 Armeria maritima.................................................................................................................................... 64 Deschampsia mackenzieana ................................................................................................................... 66 Lechea intermedia ................................................................................................................................... 67 Salix brachycarpa .................................................................................................................................... 68 Salix silicicola ........................................................................................................................................... 68 Salix turnorii ............................................................................................................................................ 69 Salix tyrrellii ............................................................................................................................................. 69 Stellaria arenicola ................................................................................................................................... 70 Tanacetum huronense ............................................................................................................................ 71 Recommendations for Future Research ..................................................................................................... 72 Conclusion ................................................................................................................................................... 73 Literature Cited ........................................................................................................................................... 74 7 Lamb et al. 2011. Athabasca Endemics Occupancy Survey Acknowledgements The Saskatchewan Ministry of Tourism, Culture, Parks and Sport provided planning, funding, and logistical support for the occupancy surveys in both 2009 and 2010. The Habitat Stewardship Program (HSP) of Environment Canada provided funding for the 2010 occupancy survey. The 2009 fieldwork was sponsored under contract K4E21-09-1056 with Environment Canada. The surveys were conducted by very enthusiastic teams including: - Mike Anderson (Information Management and Geomatics Services Branch, Ministry of Environment) - Dr George Argus (Canadian Museum of Nature) - Digit Guedo (Department of Plant Sciences, University of Saskatchewan; both 2009 and 2010) - Murray Hilderman (Environmental Protection Branch, Ministry of Environment) - Sarah James (Environmental Assessment Branch, Ministry of Environment) - Jessus Karst (Nature Saskatchewan; both 2009 and 2010) - Jeff Keith (Fish and Wildlife Branch, Ministry of Environment) - Kelvin Kelly (Parks Service, Ministry of Tourism, Parks, Culture and Sport) - Dr. Eric Lamb (Department of Plant Sciences, University of Saskatchewan) - Glen Longpre (Parks Service, Ministry of Tourism, Parks, Culture and Sport) - Anna Leighton (Independent Consultant, Saskatoon) - Jenalee Mischkolz (Department of Plant Sciences, University of Saskatchewan) - Susan McAdam (Fish and Wildlife Branch, Ministry of Environment) - Candace Neufeld (Canadian Wildlife Service) - Chet Neufeld (Native Plant Society of Saskatchewan) - Jeanette Pepper (Fish and Wildlife Branch, Ministry of Environment) - Jim Smith (Parks Service, Ministry of Tourism, Parks, Culture and Sport ) - Allison Tucker (Environmental Protection Branch, Ministry of Environment) - Matt Weiss (Nature Saskatchewan) - Sarah Vinge (Nature Saskatchewan) - Bob Wilson (Parks Service, Ministry of Tourism, Parks, Culture and Sport) - Dr. Rob Wright (Parks Service, Ministry of Tourism, Parks, Culture and Sport) GIS development and transect selection was performed by Sarah Lowe and Dr. Darcy Henderson (Canadian Wildlife Service) and Jessus Karst (Nature Saskatchewan). Amanda Guy (University of Saskatchewan) assisted with report preparation. Cover Photo by Digit Guedo. Armeria maritima on a gravel pavement in the William River Dunes. 8 Lamb et al. 2011. Athabasca Endemics Occupancy Survey Introduction The Athabasca sand dunes are a unique landscape in northern Saskatchewan characterized by large regions of active sand dunes and a unique flora (Hermesh 1972, Smith 1978, Mackenzie River Basin Committee 1981, Raup and Argus 1982, Jonker and Rowe 2001). This landscape is the largest complex of active sand dunes in Canada and contains a wide array of sand dune forms including very large longitudinal dunes with crests more than 30m above the surrounding landscape. The region is currently protected as part of the Athabasca Sand Dunes Provincial Wilderness Park. The Athabasca sand dune region is of high conservation value due to the presence of ten endemic vascular plant taxa (Raup 1936, Mackenzie River Basin Committee 1981, Raup and Argus 1982). These endemic taxa, variously classified as species, subspecies, or varieties (Table 1) (Harms 2003). In general these species are characterized by traits necessary to survive in an environment dominated by moving sand. Traits to cope with burial include vertical growth forms and aggressive adventitious rooting. Traits including thick epidermises and densely hairy leaves are likely adaptations to water stress and abrasion by sand. Table 1: Endemic plant taxa recognized in the Athabasca sand dunes. Nomenclature follows Harms (2003). In the remainder of the report variety names are not used. Family Species Common name Asteraceae Achillea millefolium var. megacephala (Raup) Large headed woolly yarrow Boivin Tanacetum huronense Nutt. var. floccosum Raup Floccose Tansy Caryophyllacae Stellaria arenicola Raup Sand starwort; Sand stitchwort Cistaceae Lechea intermedia Leggett ex. Britt. var. Impoverished pinweed depauperata Hodgdon Plumbaginaceae Armeria maritima (P.Mill) Willd. ssp. interior Athabasca thrift (Raup) Pors. Poaceae Deschampsia mackenzieana Raup Mackenzie hairgrass Salicaceae Salix brachycarpa Nutt. var. psammophila Raup Sand-loving or Sand-dune short-capsuled willow Salix silicicola Raup Blanket-leaf or felt-leaf willow Salix turnorii Raup Turnor’s willow Salix tyrrellii Raup Tyrrell’s willow All of the Athabasca sand dunes endemics have been assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) (Environment Canada 2010). Years indicate the date of assessment. Lechea intermedia var. depauperata (1997) is designated as “Data Deficient”. Achillea millefolium var. megacephala (2000), Armeria maritima ssp. interior (2002), Deschampsia mackenzieana (2001), Salix brachycarpa var. psammophila (2000), Salix silicicola (2000), Salix turnorii (2000), and Tanacetum huronense var. floccosum (2000) are listed as of “Special Concern”. Salix tyrrellii (2000), and Stellaria arenicola (1992) are listed as “Not at Risk”. The Species at Risk Act (SARA) came into effect in 2004 with all of the Athabasca endemics listed as “Species of Special Concern” with the exceptions of Salix tyrrellii and Stellaria arenicola (“Not at Risk”) and Lechea intermedia (not listed). A range of potential threats to the Athabasca sand dunes endemic flora have been recognized (Mackenzie River Basin Committee 1981, Environment Canada 2010). Climate change has the potential 9 Lamb et al. 2011. Athabasca Endemics Occupancy Survey to alter the distribution and extent of dune habitats, and may favour the invasion of sand-adapted species from the south. Local disturbance by ecotourism, all-terrain vehicles (ATVs), and mineral exploration has the potential to injure or kill individual plants, and may alter habitats to favour of undesirable species. Gravel pavement habitats in particular may be vulnerable to even light foot traffic. Exotic species invasions pose a particularly significant threat because of the potential for hybridization between native sand dune species and closely related invasive species. Finally, the Athabasca sand dunes are subject to acid deposition largely originating with oil and gas and uranium mining activity (Aherne 2008, Whitfield et al. 2010). Current deposition is not estimated to exceed critical loads (Aherne 2008), however given the ongoing expansion of resource extraction in northern Alberta and Saskatchewan, acid deposition is likely to remain a significant potential threat. Evaluation of the potential threats to the Athabasca sand dunes requires both a detailed understanding of the population sizes and habitat affinities of the endemic taxa, and long-term monitoring of selected populations. Little is known about the full range extent or population sizes of the Athabasca endemics. Extensive botanical research has been conducted in the sand dunes into the taxonomic relationships and habitat affinities (Raup 1936, Hermesh 1972, Mackenzie River Basin Committee 1981, Raup and Argus 1982, Macdonald et al. 1987, Macdonald and Chinnappa 1989, Purdy et al. 1994, Purdy and Bayer 1995b, a, Purdy and Bayer 1996) of the endemic species, but only limited quantitative ecological data on the populations exist. The only widespread quantitative data available were collected in 1979 and 1980 as part of the Mackenzie River Basin baseline assessment (Mackenzie River Basin Committee 1981). In that study the relative abundance of vascular and non-vascular plant species were estimated in representative areas including the Cantara lake, Thompson Bay, and MacFarlane river dune fields. No data were collected from the William river dune field in that study. These data were used to produce detailed plant community classifications and descriptions, but are insufficient for projections of the population sizes of the endemic species in the region. An extensive occupancy survey was conducted in August 2009 in the Cantara lake, Thompson Bay, and William River dune fields. A second survey was conducted in 2010 covering the same areas and in addition the Archibald Lake and MacFarlane River dune fields. The primary purpose of this report is to quantitatively document the distribution and abundance of the endemic vascular flora of the Athabasca sand dunes. This report supersedes the report on the 2009 field survey (Lamb 2010) as all data included in that report are also summarized here. Field Survey Methods A field survey of pre-located 250m transects (Figure 1 - Figure 3) was conducted between August 18 and August 27, 2009 by a team of 12 people and between August 10 and August 18, 2010 by a team of 12 people. The transect selection and sampling procedures are described in this section. Initial pre-trip and on-site training was conducted in both years to ensure that all survey team members were familiar with the survey methodology and able to accurately identify the target taxa. Taxonomic experts George Argus and Anna Leighton were present on site in 2009 and led the species identification training. They provided ongoing advice on uncertain specimens as needed. Digit Guedo and Jessus Karst were members of the field teams in both years and led the identification and survey method training in 2010. All survey teams were provided with a laminated booklet containing photos of all target taxa, and were encouraged to take photographs of uncertain specimens for later confirmation. All survey teams participated in the on-site survey of a training transect under the supervision of Eric Lamb and Rob Wright (2009) or Digit Guedo and Jessus Karst (2010) prior to beginning work. All data were recorded on 10 Lamb et al. 2011. Athabasca Endemics Occupancy Survey