Recovery Strategy for the Short-rayed Alkali Aster (Symphyotrichum frondosum) in Canada – 2013
Species at Risk Act
Recovery Strategy Series
Adopted under Section 44 of SARA
Short-rayed Alkali Aster
The federal Recovery Strategy for the Short-rayed Alkali Aster in Canada consists of two parts:
Part 2: Recovery Strategy for the short-rayed alkali aster (Symphyotrichum frondosum) in British Columbia, prepared by the Short-rayed Alkali Aster Recovery Team, for the British Columbia Ministry of Environment.
Table of Contents
- Additions and Modifications to the Adopted Document
- 1. Species Status Information
- 2. Socio-economic Considerations
- 3. Recovery Feasibility
- 4. Population and Distribution Objectives
- 5. Critical Habitat
- 6. Statement of Action Plans
- 7. Effects on the Environment and Other Species
- 8. References
- Appendix 1. Maps of critical habitat for Short-rayed Alkali Aster in Canada
Part 2: Recovery Strategy for the short-rayed alkali aster (Symphyotrichum frondosum) in British Columbia, prepared by the Short-rayed Alkali Aster Recovery Team, for the British Columbia Ministry of Environment
Recovery Strategy for the Short-rayed Alkali Aster (Symphyotrichum frondosum) in Canada – 2013
For copies of the recovery strategy, or for additional information on species at risk, including COSEWIC Status Reports, residence descriptions, action plans, and other related recovery documents, please visit the Species at Risk (SAR) Public Registry.
Cover illustration: Terry T. McIntosh
Également disponible en français sous le titre
« Programme de rétablissement de l’aster feuillu (Symphyotrichum frondosum) au Canada »
© Her Majesty the Queen in Right of Canada, represented by the Minister of the Environment, 2013. All rights reserved.
Catalogue number En3-4/163-2013E-PDF
Content (excluding the illustrations) may be used without permission, with appropriate credit to the source.
Part 1: Federal Addition to the “ Recovery Strategy for the short-rayed alkali aster (Symphyotrichum frondosum) in British Columbia”, prepared by Environment Canada
The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996) agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c.29) (SARA), the federal competent ministers are responsible for the preparation of recovery strategies for listed Extirpated, Endangered, and Threatened species and are required to report on progress within five years.
The Minister of the Environment is the competent minister for the recovery of the Short-rayed Alkali Aster and has prepared the federal component of this recovery strategy (Part 1), as per section 37 of SARA. It has been prepared in cooperation with the Department of Fisheries and Oceans Canada (as a SARA-participating agency), and the British Columbia Ministry of Environment. SARA section 44 allows the Minister to adopt all or part of an existing plan for the species if it meets the requirements under SARA for content (sub-sections 41(1) or (2)). The British Columbia Ministry of Environment led the development of the attached recovery strategy for the Short-rayed Alkali Aster (Part 2) in cooperation with Environment Canada.
Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy and will not be achieved by Environment Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of the Short-rayed Alkali Aster and Canadian society as a whole.
This recovery strategy will be followed by one or more action plans that will provide information on recovery measures to be taken by Environment Canada and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.
The following sections have been included to address specific requirements of SARA that are not addressed in the “Recovery Strategy for the short-rayed alkali aster (Symphyotrichum frondosum) in British Columbia” (Part 2 of this document, referred to hereafter as “the provincial recovery strategy”). In some cases, these sections may also include updated information or modifications to the P/T recovery strategy for adoption by Environment Canada.
Legal Status: SARA Schedule 1 (Endangered) (2007)
|Global (G) Rank||National (N) Rank||Sub-national (S) Rank||COSEWICDesignation||B.C. List||B.C. Conservation Framework|
United States (NNR)
|Canada: British Columbia (S1), United States: Arizona (SNR), California (SNR), Colorado (SNR), Idaho (SNR), Maine (SNR), Montana (SH), Nevada (SNR), New Mexico (SNR), Oregon (SNR), Utah (SNR), Washington (SNR), Wyoming (S2)||Endangered (2006)||Red||Highest priority: 1, under Goal 3**|
* Rank 1– critically imperiled; 2– imperiled; 3- vulnerable to extirpation or extinction; 4- apparently secure; 5– secure; H– possibly extirpated; NR – status not ranked
** The three goals of the B.C. Conservation Framework are: 1. Contribute to global efforts for species and ecosystem conservation; 2. Prevent species and ecosystems from becoming at risk; 3. Maintain the diversity of native species and ecosystems
It is estimated that the percent of the global range of this species in Canada is less than 1%.
The “Recovery Strategy for the short-rayed alkali aster (Symphyotrichum frondosum) in British Columbia” contains a short statement on socio-economic considerations. As socio-economic analysis is not required under Section 41(1) of SARA, the Socio-economic Considerations section of the “Recovery Strategy for the short-rayed alkali aster (Symphyotrichum frondosum) in British Columbia” is not considered part of the Minister of the Environment's recovery strategy for this species.
This section replaces the “Recovery Feasibility” section in the provincial recovery strategy.
Recovery of the Short-rayed Alkali Aster (Symphyotrichum frondosum) is considered technically and biologically feasible based on the following four criteria outlined in the draft SARA Policies (Government of Canada 2009):
Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future, to sustain the population or improve its abundance.
Yes, the current populations of Short-rayed Alkali Aster are capable of reproducing; most members of the Asteraceae family reproduce readily from seed.
Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.
Yes, there is sufficient suitable habitat for this species, and additional suitable habitat might also be made available through habitat management or restoration.
The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.
Yes, through effective management for this species, including the potential control of invasive species, some of the primary threats can be mitigated.
Recovery techniques exist to achieve the population and distribution objectives, or can be expected to be developed within a reasonable timeframe.
Yes, general recovery methods and techniques for the recovery of this species already exist.
This section replaces the “Recovery Goal” section in the provincial recovery strategy.
Environment Canada has determined the Population and Distribution Objective for Short-rayed Alkali Aster to be:
To maintain the distribution, and to maintain or (where feasible) improve the abundance, of all known extant populations of this species in Canada, as well as any other extant populations that may be identified in Canada.
Abundance and distribution information for this species shows eight confirmed extant populations on federal and non-federal land in the southern interior of B.C. (2007, 2003 surveys; as per data available in the provincial recovery strategy, and from the BC CDC). There is no information to confirm that the species was previously more widespread, therefore an objective to actively increase the number of populations, which may allow for down-listing of the species, is not appropriate. However, if additional naturally occurring populations are discovered, they should also be maintained. The rate of change in population size for extant populations is unknown; it is important to note for future monitoring and/or trend estimation purposes, that the population size of this annual species may characteristically fluctuate between survey years (Bush and Lancaster 2004). Where the best available information and/or long-term monitoring indicates overall population decline, deliberate attempts to improve abundance (e.g., through seeding or change in land use management) are appropriate.
In reference to potential additional extant populations of Short-rayed Alkali Aster, two small occurrences have been reported in the Fraser Valley, B.C., at (1) New Westminster (2006), and (2) at Surrey (1994). These occurrences were not included in the provincial recovery strategy (2009) owing to their characterization as apparently incidental, non-viable populations. In 2011, Environment Canada reviewed the historical and existing information for these records. Frank Lomer (2011 pers. comm.), the original observer of both Fraser Valley occurrences, indicated that Short-rayed Alkali Aster has not persisted at either site, and that neither location comprises suitable habitat for Short-rayed Alkali Aster at present. However, Lomer notes that the Surrey population likely came in with dredged sand from the Fraser River, indicating Short-rayed Alkali Aster might occur (or have occurred) in the Thompson/Fraser drainage.
This section replaces the “Critical Habitat” section in the provincial recovery strategy.
Section 41 (1)(c) of SARA requires that recovery strategies include an identification of the species’ critical habitat, to the extent possible, as well as examples of activities that are likely to result in its destruction. The 2009 provincial recovery strategy for Short-rayed Alkali Aster noted that critical habitat could not be identified at that time (nor is it required in the provincial process), owing to a lack of information on habitat and area requirements for the species. This federal document does identify critical habitat to the extent possible for Short-rayed Alkali Aster. For populations with critical habitat identified in this recovery strategy, more precise boundaries may be mapped, and additional critical habitat may be added in the future, if additional research supports greater inclusion of areas beyond what is currently identified. A primary consideration in the identification of critical habitat is the amount, quality, and locations of habitat needed to achieve the population and distribution objectives.
Critical habitat for Short-rayed Alkali Aster is identified for five of the eight confirmedextant populations in the south interior of British Columbia. Critical habitat could not be identified for three of the eight known extant populations, owing to a lack of geographic information (i.e., population location details are not sufficient for this purpose). Available data and descriptions for these three populations, shown below, indicate a geographical range of greater than 10 kilometers of shoreline, for an unknown number of plants. Detailed geographic information for these three populations is not currently available to Environment Canada. The three populations that do not have critical habitat identified at this time are described as follows (refer to provincial recovery strategy for details):
- Osoyoos Lake, northeast shore (EO2): 50-70 plants (in 1993)
- Osoyoos Lake, east shore (EO6): ≥40 plants over 200 m² (in 1999)
- Osoyoos Lake, southeast shore (EO3): 5 plants / m²; total area unspecified (in 2002)
Environment Canada endeavours to engage the appropriate individuals and agencies such that the sharing of spatial occurrence data will be granted, and so that the critical habitat for this population may be completely identified in due course.
Ecological attributes of Short-rayed Alkali Aster habitat are outlined in the provincial recovery strategy, and in the COSEWIC status report (COSEWIC 2006):
Short-rayed Alkali Aster is found predominantly in the Bunchgrass Biogeoclimatic Zone in the southern Okanagan Valley. This area is characterized as having a semi-arid steppe climate, with cold winters. Summers are hot and dry, with low mean annual rainfall (300 mm) and relatively short growing seasons.
Within these environments, Short-rayed Alkali Aster has been reported from lakeshore habitats including sandy beaches (Osoyoos Lake), and from the lightly sloping draw-down zone of lakes and ponds (Vaseux Lake, Skaha Lake, Max Lake). Two isolated plants have also been reported along the edge of the Fraser River (Surrey, and New Westminster B.C.).
Seasonally fluctuating water levels are important to population dynamics. Short-rayed Alkali Aster is a late emergent, wet shoreline species; plants germinate when water levels recede in later summer months.
Short-rayed Alkali Aster is associated with sandy shorelines, and edges of ponds, lakes, and rivers, in areas that experience seasonal flooding. Ecosystem processes that occur along shorelines (e.g., extent of water level fluctuation, duration of flooding; also nutrient cycling and sedimentation properties) are integral to the production and maintenance of suitable microhabitat conditions for Short-rayed Alkali Aster. Shoreline erosion and microclimate will be directly affected by development or landscape alteration in proximal areas.
Critical habitat for Short-rayed Alkali Aster in Canada is identified as the area occupied by individual plants or patches of plants, including the associated potential location error from GPS units (ranging from 13 m to 25 m uncertainty distance), plus an additional 50 meters (i.e., critical function zone distance) to encompass immediately adjacent areas. Critical habitat also includes the entire portion of distinct ecological features which are associated with, and are integral to, the production and maintenance of suitable habitat conditions. Distinct ecological features identified as critical habitat for Short-rayed Alkali Aster include: seasonally-flooded shorelines (down to the lowest documented water level), as well as the associated draw-down zone adjacent to shorelines. Shoreline habitats are maintained via extent of water level fluctuation, duration of flooding, nutrient cycling, and sedimentation properties. Where occurrences are in close proximity (location uncertainty plus critical function zone boundaries are less than 100 m apart), and/or where they occur in association with the same distinct ecological feature, showing continuous suitable habitat characteristics between them, connective habitat (i.e., the area in-between occurrences) is identified as critical habitat.
Areas containing critical habitat are shown in Appendix 1. The polygons shown were derived to closely encompass the occurrences, plus location error, plus critical function zone distance as well as connective habitat and portions of distinct ecological features, where appropriate. The polygons shown on each map thus represent actual critical habitat, excluding established anthropogenic features and standing water, as follows. Given that existing anthropogenic features (including active roads, establish building structures) do not possess the ecological attributes required for the Short-rayed Alkali Aster, they are not included as critical habitat, even when they occur within the minimum critical function zone distance (i.e., 50 m plus GPS error) of the plant occurrence. Permanent standing water below the lowest documented water line is not identified as critical habitat. Should it be determined through further study that these features do provide an essential ecological function, the identification of critical habitat will be updated accordingly. Detailed methods and decision-making processes relating to critical habitat identification are archived in a supporting document.
It is recognized that the critical habitat identified above is insufficient to achieve the population and distribution objectives for the species. The schedule of studies (Section 5.2) outlines the activities required to identify additional critical habitat necessary to support these objectives.
This section replaces the “Recommended schedule of studies to identify critical habitat” section in the provincial recovery strategy.
The following schedule of studies (Table 2) will enable the identification of critical habitat for additional populations of Short-rayed Alkali Aster in Canada.
Additional spatial data is required to identify critical habitat at locations for three known extant populations occurring at Osoyoos Lake, B.C.Environment Canada endeavours to engage the appropriate individuals and agencies such that the sharing of spatial occurrence data will be granted, and so that the critical habitat for these populations may be identified in due course.
Two additional occurrences of Short-Rayed Alkali Aster were found in the Fraser Valley (1994, 2006), but plants have not been observed to persist (2011). At this time, it is not known if viable propagules remain in the seed bank, and/or if these records indicate a greater range of distribution, e.g., locally opportunistic occurrences, in the area or near vicinity.
Understanding what constitutes destruction of critical habitat is necessary for the protection and management of critical habitat. Destruction is determined on a case by case basis. Destruction would result if part of the critical habitat were degraded, either permanently or temporarily, such that it would not serve its function when needed by the species. Destruction may result from a single or multiple activities at one point in time or from the cumulative effects of one or more activities over time. The provincial recovery strategy provides a detailed description of limitations and potential threats to Short-rayed Alkali Aster. Activities described in Table 3 include those likely to cause destruction of critical habitat for the species; destructive activities are not limited to those listed.
|Activity||Description of activity resulting in or contributing to the destruction of critical habitat||Threat level|
|Inappropriate lake water level control (as implemented by human management of outlet dams) for flood control, drinking water or irrigation purposes, causing water level stabilization and/or abnormal fluctuations||Results in suppression of natural flood/drought cycles and water level regimes such that hydrological qualities and processes are beyond the niche tolerance range of Short-rayed Alkali Aster; water levels artificially maintained at too-high or too-low levels, or that are prevented from fluctuating required amounts at appropriate times, will prevent successful completion of one or more life history stages, i.e., germination, growth, and/or flowering.||High|
|Deliberate destruction of natural shoreline for recreation, residence, or agriculture, including: creation of structures, removal of vegetation or natural substratum||Results in direct habitat loss by creation of structures (e.g., docks, boat ramps, boat houses, and sheds), or by removal of seed bank and natural substratum required for growth (e.g., vegetation removal as a function of beach maintenance/aesthetics, or lawn creation) in areas identified as critical habitat for the Short-rayed Alkali Aster.||High|
|Introducing detrimental patterns of disturbance in areas occupied by, or proximal to, Short-rayed Alkali Aster, including: excessive recreational use (e.g., ATVs, hiking, boat damage, trampling by swimmers), trampling by livestock, or landscape development||Detrimental disturbance patterns cause direct and indirect habitat loss by altering natural ecological processes and dynamics required for perpetuation. The nature and magnitude of disturbance dynamics will impact local water and nutrient cycling, as well as substratum characteristics (e.g., erosion, compaction) which influence success of seed set, dormancy, germination, and growth. Damaging ecological processes in occupied and/or immediately adjacent areas will have immediate and cumulative effects on the quality and availability of habitat for Short-rayed Alkali Aster.||High|
|Deliberate introduction of alien invasive plants, or efforts to control existing invasive species||Alien invasive species cause direct reduction of habitat available for Short-rayed Alkali Aster, and indirect effects, e.g., alteration of shade, water, and nutrients available to exclude niche range of Short-rayed Alkali Aster. Efforts to control invasive plants through mechanical or chemical means can likewise result in habitat alteration such that it is no longer suitable for Short-rayed Alkali Aster.||Moderate|
Habitat destruction from water level stabilization and/or abnormal fluctuations has been identified as a major threat to Short-rayed Alkali Aster populations. The water levels of Osoyoos Lake, Vaseux and Skaha Lake (in combination, associated with 7 of the 8 known extant populations) are managed by outlet dams. Shoreline species are adapted to fluctuating water levels, including regular flooding and summer draw-down with associated siltation and wave action that reduces organic matter, and, ultimately, reduces competition. Water levels are artificially controlled at all of the known extant sites in B.C. If lake levels are maintained too high or too low, or if water levels are maintained at one level too long, such that extended flooding or drying results (i.e., preventing natural fluctuations), this will reduce the critical habitat available to Short-rayed Alkali Aster, as well as the successful persistence or emergence of seeds from the seed bank, and any subsequent recruitment.
Habitat loss through shoreline destruction and development has also been identified as a major threat to Short-rayed Alkali Aster. The ecological preference of Short-rayed Alkali Aster for lakeshore habitat makes it particularly threatened by residential developments (including associated landscaping activities), and local recreational beach-use activities (i.e., for boating, camping, walking, or swimming). In some instances, it would appear that some level of human disturbance benefits this species, owing to its preference for recently-disturbed habitat and reduced competition with other vegetation. Anthropogenic activities such as roto-tilling and sand-sifting beach areas to reduce weed encroachment may benefit Short-rayed Alkali Aster by mimicking natural disturbance regimes, like wave and storm action. However, appropriate timing (pre-germination, and post-seed set) and duration of these activities is essential. Excessive beach use by sunbathers, boaters, recreational vehicles, and children digging, as well as trampling by livestock (particularly in post-germination and pre-seed set periods), appears to severely affect habitat quality and characteristics such that it is no longer suitable for Short-rayed Alkali Aster. Encroachment or in-filling shoreline areas for lawns, docks, or construction of a breakwater also causes direct destruction of critical habitat. Nutrient loading in these heavily used lakes may also be a concern, as this species’ preferred habitat is low in nutrient availability.
Invasive non-native species are a threat to this species, particularly in absence of natural water level fluctuations that can provide natural controls. Invasive plants White Sweet Clover (Melilotus alba), Purple Loostrife (Lythrum salicaria), Houndstongue (Cynoglossum officinale), Giant Burdock (Arctium lappa), Canada Thistle (Cirsium arvense), Diffuse Knapweed (Centaurea diffusa), and Sulphur Cinquefoil (Potentilla recta), have been reported to occur with Short-rayed Alkali Aster at sites in the south interior of B.C. Invasive alien plants reduce available habitat by competing for resources, and concurrently, by altering the quality of resources available to Short-rayed Alkali Aster (e.g., space, water, light, nutrients). However, efforts to control these species may also cause inadvertent mechanical or chemical damage to Short-rayed Alkali Aster habitat.
An action plan will be posted on the Species at Risk Public Registry by 2018.
A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making.
Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that strategies may also inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the strategy itself, but are also summarized below in this statement.
Short-rayed Alkali Aster occurs in the South Okanagan Valley, where other rare species are found. Critical habitat identified for Short-rayed Alkali Aster is known to overlap with critical habitat identified for other shoreline plants in the area that are characterized as species at risk. For example, the SARA Schedule 1 plant species Toothcup (Rotala ramosior), Scarlet Ammannia (Ammannia robusta), Small-flowered Lipocarpha (Lipocarpha micrantha), and Bent Spike-rush (Eleocharis geniculata) also occur at the Osoyoos Lake sites. The provincially rare Awned Cyperus (Cyperus squarrosus) is known to co-occur in this area as well.
The proposed recovery approaches are not expected to negatively affect any other species. The recommended habitat protection will indirectly benefit other species at risk in the area; increased public education and awareness may limit harmful recreational activities at these locations, and management of invasive species may restore habitat for other plant species at risk. In acknowledgement of the high potential for shared habitat among local species at risk, large-scale management actions, such as invasive species removal or the use of herbicides, should be planned and implemented carefully. All on-site activities (surveys, research, and management) to aid recovery of Short-rayed Alkali Aster may pose a threat to co-occurring species (e.g., via trampling, increased herbivory, or inadvertent dispersal of alien species during disposal), unless care is taken to avoid damage.
B.C. Conservation Data Centre. 2011. BC Species and Ecosystems Explorer. B.C. Minist. of Environ. Victoria, B.C. (Accessed July 13, 2011).
B.C. Conservation Framework. 2011. Conservation Framework Summary: Symphyotrichum frondosum. B.C. Minist. of Environment. Victoria, B.C. (Accessed July 13, 2011).
Bush, D., and J. Lancaster. 2004. Rare annual plants – problems with surveys and assessments. Prairie Conservation and Endangered Species Conference, February 28, 2004.
COSEWIC. 2006. COSEWIC assessment and status report on the short-rayed alkali aster Symphyotrichum frondosum in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 22 pp.
Government of Canada. 2009. Species at Risk Act Policies, Overarching Policy Framework [Draft]. Species at Risk Act Policy and Guidelines Series. Environment Canada. Ottawa. 38 pp.
NatureServe. 2011. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. (Accessed: July 13, 2011).
In Canada, Short-rayed Alkali Aster occurs at eight locations on federal and non-federal land, in the south interior of British Columbia. Critical habitat for five of the eight known extant populations has been identified, i.e., at Max Lake (Figure A1), Skaha Lake (Figure A2), Vaseux Lake (Figure A3-A4), northwest Osoyoos Lake (Figure A5), and southwest Osoyoos Lake (Figure A6).
Figure A1. Area containing critical habitat for Short-rayed Alkali Aster near Penticton, B.C. (Madeline Lake/Max Lake, EO7 in Provincial Recovery Strategy). The polygon indicates an area of 2.4 ha. Existing anthropogenic features within the indicated polygon, including active roads, are not identified as critical habitat. Permanent standing water (i.e., below the lowest documented water-level line) is not identified as critical habitat.
Figure A2. Area containing critical habitat for Short-rayed Alkali Aster near Okanagan Falls, B.C. (Christie Memorial Provincial Park, EO5 in Provincial Recovery Strategy). The polygon indicates an area of 4.6 ha. Existing anthropogenic features within the indicated polygon, including active roads and houses, are not identified as critical habitat. Permanent standing water (i.e., below the lowest documented water-level line) is not identified as critical habitat.
Figure A3. Area containing critical habitat for Short-rayed Alkali Aster at Vaseux Lake, B.C. (north sub-population of EO4, comprising the portion of the population described in Provincial Recovery Strategy). The polygon indicates an area of 11.4 ha. Existing anthropogenic features within the indicated polygon, including active roads and houses, are not identified as critical habitat. Permanent standing water (i.e., below the lowest documented water-level line) is not identified as critical habitat.
Figure A4. Area containing critical habitat for Short-rayed Alkali Aster at Vaseux Lake (south sub-population of EO4, not included in Provincial Recovery Strategy), B.C. The polygon indicates an area of 2.3 ha. Existing anthropogenic features within the indicated polygon, including active roads and houses, are not identified as critical habitat. Permanent standing water (i.e., below the lowest documented water-level line) is not identified as critical habitat.
Figure A5. Area containing critical habitat for Short-rayed Alkali Aster at northwest Osoyoos Lake, B.C. (EO9 in Provincial Recovery Strategy). The polygon indicates an area of 3.4 ha. Existing anthropogenic features within the indicated polygon, including active roads and houses, are not identified as critical habitat. Permanent standing water (i.e., below the lowest documented water-level line) is not identified as critical habitat.
Figure A6. Area containing critical habitat for Short-rayed Alkali Aster at southwest Osoyoos Lake, B.C. (EO8 in Provincial Recovery Strategy). The polygon indicates an area of 2.3 ha. Existing anthropogenic features within the indicated polygon, including active roads, houses, and the associated developed urban and residential landscape, are not identified as critical habitat. Permanent standing water (i.e., below the lowest documented water-level line) is not identified as critical habitat.
Footnotes -- Part 1
1“Populations” are generally characterized as being separated by >1 km, and “sub-populations” represent records of individuals, or patches of individuals, that are within 1 km of each other. In some cases, dispersal dynamics and the species’ ecology warrant customized population separation distances. For one known extant population of Short-rayed Alkali Aster at Vaseux Lake, B.C., the northern and southern “sub-populations” are actually 1.75 km apart. The features comprising this occurrence were considered to share linear shoreline water-current flow, and so were identified as one population by the B.C.Conservation Data Centre (Marta Donovan, pers. comm. 2011).
2 These five populations were re-confirmed in 2007, and 2003 surveys.
3EO numbers refer to Element Occurrences tracked by the British Columbia Conservation Data Centre.
4 The draw-down zone is the area at the edge of a body of water that is frequently and/or seasonally exposed to the air owing to water-level changes caused by evaporation, water usage, and/or management of control dams.
5 Critical function zone distance has been defined as the threshold habitat fragment size required for maintaining constituent microhabitat properties for a species (e.g., critical light, moisture, humidity levels necessary for survival).
6“Distinct” ecological, or landscape features are here referred to as those that are distinguishable at a landscape scale (through use of detailed ecosystem mapping or aerial photos), which, at that scale, appear as ecologically contiguous features with relatively distinct boundaries (e.g., cliffs, banks, or slopes, drainage basins, seepage plateaus, or distinct vegetation assemblages), and which comprise the context for a species occurrence.
7 Research on germination and survival requirements, and corresponding habitat attributes such as lake levels, has been identified as a knowledge gap in the provincial recovery strategy. More detailed understanding of the effects of within- and between- year water-level fluctuation on Short-rayed Alkali Aster growth and abundance at all life history stages is required for appropriate water level control (i.e., time, level, and duration of artificial flooding).
| Part 2 |
- Date Modified: