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

This multi-species Recovery Strategy addresses the recovery of six endangered plant species inhabiting vernal pools and other ephemeral wet areas: bog bird’s-foot trefoil (Lotus pinnatus), tall woolly-heads (Psilocarphus elatior), Juncus kelloggii (Juncus kelloggii), Ranunculus alismifolius var. alismifolius (water plantain-buttercup), rosy-owl clover (Orthocarpus bracteosus), and dwarf sandwort (Minuartia pusilla). In Canada, these species occur (or occurred) primarily in Garry oak and associated ecosystems on Vancouver Island and nearby Gulf Islands where they are largely restricted to low elevation, coastal areas. Although the range of all species extends into the United States, many of the species are widely disjunct from the U.S. populations. The Recovery 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.

Four main habitat types are distinguished in this strategy: vernal pools, vernal swales, vernal seeps, and seasonally wetted wetland margins. Vernal pools are spatially discrete, seasonally flooded depressions that form on top of impermeable layers such as hardpan, claypan, or bedrock. They occur under Mediterranean-type climatic conditions that provide for winter and early spring inundation, followed by complete or partial drying in summer. Vernal swales are similar to vernal pools, but are usually shallower with less defined boundaries and shorter inundation periods. Vernal seeps are shallow flows that occur where groundwater emerges on sloping terrain, usually on the lower slopes of hillsides. 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. These habitats are all naturally highly fragmented, occurring as small isolated patches along shorelines and on small islands. Urbanization has intensified their natural fragmentation, and species occurring within them face a diverse array of threats.