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Recovery Strategy for Multi-Species at Risk in Vernal Pools and other Ephemeral Wet Areas Associated with Garry Oak Ecosystems in Canada

1. Introduction


1.1 Background

This multi-species Recovery Strategy has been developed to address the recovery of plants at risk in vernal pools and other temporally wet habitats on southern Vancouver Island and adjacent Gulf Islands. The strategy focuses on all Canadian locations of six species (Table 1): bog birds-foot trefoil (Lotus pinnatus), tall woolly-heads (Psilocarphus elatior, Pacific population), water-plantain buttercup (Ranunculus alismifolius var. alismifolius), Kellogg's rush (Juncus kelloggii), rosy owl-clover (Orthocarpus bracteosus), and dwarf sandwort (Minuartia pusilla). All six species have restricted distributions and/or small population sizes and are variously threatened by habitat loss, hydrologic alterations, and competition from invasive species (COSEWIC 2004). Unless recovery actions are initiated, these species may become extirpated from Canada. The present strategy was produced to conform to the Federal Species at Risk Act and is designed to guide the development of a Recovery Action Plan.

All of the species addressed in this document inhabit either vernal pools, wet meadows, or ephemeral seeps within Garry oak and associated ecosystems. Individual recovery goals are provided for each of the target species, along with general recommendations for recovery and management of the vernal pool ecosystem itself. The strategy comprises one component of the recovery program for Garry oak and associated ecosystems as outlined in the Recovery Strategy for Garry Oak and Associated Ecosystems and their Associated Species at Risk in Canada: 2001-2006 (GOERT 2002). In particular, this strategy comprises a component of Strategic Approach D: “Protection and recovery of species at risk” in the GOERT strategy (GOERT 2002).

This recovery strategy applies a habitat-based, multi-species approach within the broader ecosystem management framework laid out by GOERT (2002). Recovery actions that benefit the six identified species and the habitats they occupy are of immediate priority. Ultimately, the aim is to establish a general template for the recovery of all plants at risk in vernal pools. Accordingly, the overall recommendations are sufficiently general to allow for the incorporation of other species into future versions of this strategy, as resources permit or as dictated by changes in the COSEWIC status of selected species. The strategy is organized into three parts. The Introduction provides general background information common to all species, including common habitat elements as well as the rationale for taking a multi-species approach. The second section, Multi-Species Recovery, outlines the main threats to the habitat and to individual species, and suggests recovery goals for each species along with strategic approaches for meeting the recovery goals. The third section, Species Information, provides status and designation for each species along with descriptions of morphology, global and Canadian range, habitat preferences, and population trends, as far as these are known.


1.2 Stewardship approach

For successful implementation in protecting species at risk there will be a strong need to engage in stewardship on a variety of land tenures, and in particular on private land and on Indian Reserves. Stewardship involves the voluntary cooperation of landowners to protect Species at Risk and the ecosystems they rely on. It is recognized in the Preamble to the federal Species at Risk Act (SARA) that “stewardship activities contributing to the conservation of wildlife species and their habitat should be supported” and that “all Canadians have a role to play in the conservation of wildlife in this country, including the prevention of wildlife species from becoming extirpated or extinct.” It is recognized in the Bilateral Agreement on Species at Risk, between British Columbia and Canada that:

“Stewardship by land and water owners and users is fundamental to preventing species from becoming at risk and in protecting and recovering species that are at risk” and that “Cooperative, voluntary measures are the first approach to securing the protection and recovery of species at risk.”


1.3 Stewardship approach for private lands

Since many species of risk occur only or predominantly on private lands, including some of the species in this strategy, stewardship efforts will be the key to their conservation and recovery. It is recognized that to successfully protect many species at risk in British Columbia there will have to be voluntary initiatives by landowners to help maintain areas of natural ecosystems that support these species of risk. This stewardship approach will cover many different kinds of activities, such as: following guidelines or best management practices to support species at risk; voluntarily protecting important areas of habitat on private property; conservation covenants on property titles; ecogifting part or all of their property to protect certain ecosystems or species at risk; or to sell their property for conservation. For example, both government and non-governmental organizations have had good success in conserving lands in the Province. This could be aided by the B.C. Trust for Public Lands.

 

Table 1. Species addressed in this recovery strategyFootnote a, together with their COSEWIC rank and global and provincial status
SpeciesCOSEWIC StatusDate DesignatedGlobal and Provincial RankFootnote b% Of Global Range in Canada
Lotus pinnatus (bog birds-foot trefoil)EndangeredMay 2004G4G5 S1 Red<1
Psilocarphus elatior (tall woolly-heads) (Pacific population)EndangeredMay 2001G4 S1 Red<1
Juncus kelloggii (Kellogg's rush)EndangeredMay 2003G3? S1 Red<1
Ranunculus alismifolius var. alismifolius (water plantain-buttercup)EndangeredMay 2000G5T5 S1 Red<1
Orthocarpus bracteosus (rosy owl-clover)EndangeredMay 2004G3? S1 Red<1
Minuartia pusilla (dwarf sandwort)EndangeredMay 2004G5 S1 Red<1

Footnotes

Footnote A

Taxonomy and nomenclature follows Douglas et al. (1998 - 2001).

Return to footnote a

Footnote B

G=Global Conservation Status
S= Provincial Conservation Status
T= designates a rank associated with a subspecies or variety
1 = critically imperiled , 2 = imperiled, 3 = vulnerable to extirpation or extinction, 4 = apparently secure, 5 = demonstrably widespread, abundant, and secure.

Return to footnote b


1.4 Vernal pools

Vernal pools are spatially discrete, seasonally flooded depressions that form on top of impermeable layers such as hardpan, claypan, or bedrock (Holland and Jain 1977, Zedler 1987). They occur under Mediterranean and sub-Mediterranean type climatic conditions that provide for winter and early spring inundation, followed by complete or partial drying in summer. Although primarily a feature of the California floristic province (Keeley and Zedler 1998, U.S. Fish and Wildlife Service 2003), vernal pools also occur in Oregon, Washington, and southern British Columbia, where they are largely restricted to southeastern Vancouver Island, the adjacent Gulf Islands, and the dry southern interior.

Vernal pools are a unique type of wetland ecosystem. Central to their distinctive ecology is that they are ephemeral, occurring temporarily and then disappearing until the next year. They are wet long enough to differ in character and species composition from the surrounding upland habitats, while their prolonged annual dry phase prevents the establishment of species typical of more permanent wetlands (Keeley and Zedler 1998).

Vernal pools on Vancouver Island, as in California, begin to fill with rainwater in the fall and winter and exhibit four major phases: (1) the wetting phase, when pool soils become saturated, (2) the aquatic phase, when a perched water table develops and the vernal pool contains water (or alternates between being inundated and merely saturated), (3) a water-logged drying phase, when the pool begins losing water as a result of evaporation and loss to the surrounding soils but soil moisture remains high, and (4) the dry phase, when the pool and underlying soils are completely dry (Keeley and Zedler 1998). Many of the pools on Vancouver Island fill entirely from rain falling directly into the pool, but a few have a small watershed that contributes to their water inputs.

Vernal pools typically occur in landscapes that, on a broad scale, are level to gently sloping, but where complex micro-relief produces shallow, undrained depressions that retain water. Pools come in a variety of shapes and sizes, from less than 1 m2 to a hectare or more. On Vancouver Island, landforms that support vernal pool complexes are typically low-lying meadows or coastal bluffs (Ward et al. 1998). The pools on Vancouver Island tend to be of two types: those formed by rock depressions and those forming on clay soils. Rock-bottomed pools are most common on rocky bluffs, while clay-based pools occur more often in low-lying meadows. Pools in the latter habitats are sometimes fed or connected by low drainage pathways called “swales.” Swales are themselves seasonal wetted areas that remain saturated for much of the wet season. However, they are usually not inundated long enough to develop strong vernal pool or wetland vegetation characteristics. Due to their connection to adjacent pools, swales are considered important parts of the vernal pool complex. An excellent example of such a complex can be found at Uplands Park, within the District of Oak Bay on Vancouver Island.

Two other types of ephemeral wet areas mentioned in conjunction with species in this recovery strategy are “vernal seeps” and “seasonally wetted wetland margins.” Vernal seeps are shallow flows that occur where groundwater emerges on sloping terrain, usually on the lower slopes of hillsides. Seeps differ from vernal pools in that they are not usually associated with prolonged inundation; however, like vernal pools, they tend to dry up by late spring or early summer and hence present plants with similar physiological challenges. Consequently, most of the native plant species found in vernal seeps are habitat specialists not generally found in drier habitats.

Seasonally wetted wetland margins are low-lying areas next to perennial streams, lakes, or marshes that experience temporary flooding during high water periods in the winter or spring, becoming dry again during the summer. An example of this habitat type is found at Somenos Marsh, near the urban centre of Duncan.

Vernal pools, vernal swales, vernal seeps, and seasonal wetland margins contribute significantly to the biodiversity of southeastern Vancouver Island and Gulf Islands, where they form one component in a larger mosaic of Garry oak woodlands, maritime meadows, coastal bluffs, grasslands, rock outcrops, and transitional forests that comprises Garry oak and associated ecosystems (Fuchs 2001). The Garry oak community supports the highest vascular plant species diversity of any terrestrial ecosystem in coastal British Columbia (Ward et al. 1998, Fuchs 2001). Many of these are “peripheral” species that reach the northern limits of their range in southern British Columbia (Douglas et al. 2002). In the last 150 years, agricultural development, urbanization, and fire suppression have combined to eliminate or highly modify most of the original Garry oak savanna from southern Vancouver Island and adjacent Gulf Islands. It is estimated that less than five percent remains in an undisturbed condition, making this one of the most imperiled natural communities in Canada (Fuchs 2001, Lea 2002). Currently, over 90 plant taxa are listed as being at risk in Garry oak and associated ecosystems in BC, including over 20 designated by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as being at risk on a national scale. Of the latter, approximately 30 percent are associated primarily or exclusively with vernal pools or seeps (Douglas et al. 2002, Fuchs 2001).

The vernal pool plant community on southern Vancouver Island is dominated primarily by annual species, which may be better able to tolerate the cycles of extreme wetting and drying that characterize this habitat. Algal mats sometimes form a dense cover, especially in pools frequented by waterfowl. Litter cover is typically minimal, except on margins and in pools having abundant thatch-forming nonnatives like perennial ryegrass (Lolium perenneFootnote 2) and creeping bentgrass (Agrostis stoloniferaFootnote 2). Species composition is nevertheless highly variable from pool to pool, and is likely most closely related to pool size and depth, type of substrate (e.g., rock or clay), length of inundation, and the degree of encroachment by alien and native invasives. However, chance long-distance dispersal events have likely also had a role in determining current community composition. Typical vernal pool indicators on Vancouver Island and the Gulf Islands include Scouler's popcornflower (Plagiobothrys scouleri), water chickweed (Montia fontana), water-starwort (Callitriche spp.), Nuttall's quillwort (Isoetes nuttallii), Macoun's meadow-foam (Limnanthes macounii), lowland cudweed (Gnaphalium palustre), and tiny mousetail (Myosurus minimus).

Vernal pools were once widespread in California along the Pacific coast and Central Valley (Keeley and Zelder 1998) but most have been lost to urban expansion and agricultural development. It is estimated that only 3-10% of California vernal pools remain, and many vernal pool endemics are now legally protected (Witham et al. 1998). In British Columbia, hydrologic alterations resulting from wetland fills, draining, and housing construction have probably caused a similar decline in the amount and availability of vernal pool habitat during the last century. However, we have little specific information as to historical losses in the range and number of vernal pools in this region (H. Roemer, pers. comm. 2004).

Today, most of the remaining vernal pool/vernal seep habitat on Vancouver Island is confined to isolated coastal bluffs on the southeastern side of the island, and to small undeveloped islands adjacent to the coast. Soils on these bluffs develop slowly and tend to be concentrated in isolated micro-sites. This trait, combined with the characteristically thin organic layer, makes these areas highly sensitive to any type of use and development (McPhee et al. 2000). Likely the greatest impact on coastal bluffs in the past century has been the development of highly desirable ocean front property for tourism, commercial, recreational, and residential purposes.

The three remaining major “hot spots” of vernal pool plant species diversity in the region are at DND Rocky Point in the District of Metchosin, Uplands Park in the District of Oak Bay, and Trial Island Ecological Reserve near Victoria (CDC HERB Database 2004). Nevertheless, vernal pools, swales, and seeps can be found scattered throughout the Gulf Islands and along the Vancouver Island coast as far north as Campbell River and Mitlenatch Island. Harewood Plains, near the City of Nanaimo, is an important vernal pool and seepage area that supports a number of red- and blue-listed plant species (Ceska 2003). Recovery for one of these species, bog bird's-foot trefoil, is addressed in the present strategy.

Broadly speaking, the overall goals and objectives set out in this recovery strategy apply in principle to all extant vernal pools, swales, and seeps on southeastern Vancouver Island and the Gulf Islands. However, the main focus is on the survival and recovery habitats of the six species, including those upland habitats required for their maintenance (Section 2.6). The present range of the six species extends collectively from Greater Victoria to Nanaimo, with additional occurrences on Gabriola Island and Ballenas Island (Table 2, Figs. 1-4). Bog bird's-foot trefoil occurs entirely in and around Nanaimo, with a single population on Gabriola Island. Tall woolly-heads is known from Oak Bay, Saanich, and Somenos Lake near Duncan. Water plantain-buttercup is restricted to Uplands Park and Ballenas Island, while Kellogg's rush is known only from Uplands Park. Dwarf sandwort and rosy owl-clover are known from single occurrences at Rocky Pt. and Trial Island, respectively (Table 2, Figs. 1-6).

The Vancouver Island/Gulf Island populations represent the northern extent of the geographic range of each species. Isolated peripheral populations often differ genetically and morphologically from central populations (Lesica and Allendorf 1995). The ability of a species to adapt to changing ecological conditions and, therefore, its long-term survival, may rest on the conservation of these potentially distinct ecotypes (Lesica and Allendorf 1995).


1.5 Rationale for multi-species approach to recovery

The Garry Oak Ecosystems Recovery Team (GOERT) was formed to develop an ecosystem-based recovery plan for Quercus garryana and associated ecosystems, with the overall objective of ensuring the continued survival of the species, habitats, and ecological functions that sustain this globally significant biome (GOERT 2002). Other recent national initiatives have also recognized the importance of incorporating both broad- and fine-scale approaches into species conservation planning (Rodger 1998, Hermanutez et al. 2001, South Okanagan-Similkameen Conservation Program 2001, Sydenham River Recovery Team 2003), as have parallel initiatives in the U.S. (e.g., U.S. Fish and Wildlife Service 1998b) The benefits of habitat protection and ecosystem-level planning for the recovery of species at risk, and for preventing species from becoming at risk, are recognized in the recently enacted federal Species at Risk Act.

The Recovery of Nationally Endangered Wildlife (RENEW) program identifies the co-occurrence of multiple species at risk within a limited geographical area as an important criterion in determining the appropriateness of ecosystem-level planning. Although the six species covered by this strategy differ with respect to life history, demography, and microsite preferences (specific ecological requirements are discussed in the individual species accounts, under Species Information), they all share a common dependence on habitats characterized by Mediterranean-like climatic cycles of winter/spring inundation and summer desiccation. Consequently, the factors threatening survival and/or habitat tend to be similar among species.

 

Table 2. Occurrence information for bog bird's-foot trefoil, tall woolly-heads (Pacific population), Kellogg's rush, water plantain-buttercup, rosy-owl clover, and dwarf sandwort
SpeciesPopulation / OccurrenceEst. No. of PlantsYear SurveyedSourceLand Tenure/ Jurisdiction
bog bird's-foot trefoilHarewood Plains1 600 (22 sub-populations)2003Donovan 2004Private
bog bird's-foot trefoilWoodley Range120-1402003Donovan 2004BC Parks (ecological reserve)
bog bird's-foot trefoilGabriola Island65-702003Donovan 2004Private
bog bird's-foot trefoilNanaimo, White Rapids Rd.(several patches) 402003Donovan 2004Private
bog bird's-foot trefoilNanaimo, Extension Rd. (several patches)102003Donovan 2004Private
bog bird's-foot trefoilNanaimo, Extension Rd. (several patches)20-35, now possibly extirpated2003Donovan 2004; A. Ceska, pers. comm. 2004Private
bog bird's-foot trefoilNanaimo, Waddington Rd.Presumed extirpated1939Donovan 2004Unknown
bog bird's-foot trefoilNanaimo, Departure Bay Rd.Presumed extirpated1965Donovan 2004Unknown
tall woolly heads (Pacific pop.)Christmas Hill400+2004M. Miller, pers. obs.District of Saanich (nature sanctuary)
tall woolly heads (Pacific pop.)Uplands Park10 000+ (17 subpopulations)2003Fairbarns and Penny 2003District of Oak Bay (municipal park)
tall woolly heads (Pacific pop.)Somenos Marsh2 000 000+ (prior to recent dredging damage)2004Roemer 2004District of North Cowichan and The Nature Trust of BCFootnote a
tall woolly heads (Pacific pop.)Victoria, CloverdalePresumed extirpated1887Douglas et al. 2001aUnknown
tall woolly heads (Pacific pop.)Victoria, Cedar HillPresumed extirpated1887Douglas et al. 2001aUnknown
tall woolly heads (Pacific pop.)UclueletPresumed extirpated1909Douglas et al. 2001aUnknown
tall woolly heads (Pacific pop.)Sidney, Roberts BayPresumed extirpated1913Douglas et al. 2001aUnknown
tall woolly heads (Pacific pop.)Sidney, Swartz BayPresumed extirpated1931Douglas et al. 2001aUnknown
tall woolly heads (Pacific pop.)Francis/King ParkStatus unknown1962Douglas et al. 2001aCapital Regional District (CRD) Park
tall woolly heads (Pacific pop.)UVicExtirpated1976A. Ceska, pers. comm.University of Victoria
Kellogg's rushUplands Park1 000-1 5002003A. Ceska, pers. comm.District of Oak Bay (municipal park)
water plantain-buttercupCadboro Bay / Oak BayExtirpated (possibly numerous populations)1918RBCM HerbariumUnknown
water plantain-buttercupUplands Park1032005M. Miller, pers. obs.District of Oak Bay (municipal park)
water plantain-buttercupUplands Park362005M. Miller, pers. obs.District of Oak Bay (municipal park)
water plantain-buttercupBallenas Island112005M. Miller, pers. obs.Department of National Defence
water plantain-buttercupBallenas Island802005M. Miller, pers. obs.Department of National Defence
rosy owl-cloverTrial Island4472002M. Fairbarns, pers. comm.BC Parks (ecological reserve)
rosy owl-cloverTrial Island3662003M. Fairbarns, pers. comm.BC Parks (ecological reserve)
rosy owl-cloverTrial Island472004M. Fairbarns, pers. comm.BC Parks (ecological reserve)
rosy owl-cloverTrial Island210-2302005M. Fairbarns, pers. comm.BC Parks (ecological reserve)
dwarf sandwortRocky Point80-1202005M. Fairbarns, pers. comm.Department of National Defence

Footnotes

Footnote A

The tall woolly-heads population occurs in a narrow zone along Somenos Creek, just outside and paralleling the boundary of the Somenos Garry Oak Protected Area, on District of North Saanich land. The Protected Area is owned by The Nature Trust of British Columbia and is managed by the BC Ministry of Environment.

Return to footnote a

At present, there may be fewer than a hundred functioning vernal pool complexes remaining in southwestern BC (H. Roemer, pers. comm. 2004). A substantial proportion of these support occurrences of rare plants. Several of the sites addressed in this strategy, such as Uplands Park, provide habitat for COSEWIC-listed species not directly discussed here (e.g., Macoun's meadowfoam), and COSEWIC status reports have recently been prepared or are underway for several other species (e.g., Muhlenberg's centaury, winged water-starwort). Taking a multi-species approach to recovery planning will facilitate the inclusion of additional taxa with similar ecological requirements into future versions of this strategy, while encouraging the development of long-term objectives that potentially benefit all native vernal pool plant inhabitants.

Footnotes

Footnote 2

Used hereon to designate species nonnative to British Columbia.

Return to footnote 2