Name:
Downingia spp. - Callitriche spp. - Eryngium spp. North Pacific Vernal Pool Group
Reference:
NatureServe Biotics 2019
Description:
This group includes herbaceous wetlands that surround and occur within shallow ephemeral water bodies found in depressions among grasslands, shrub-steppe and open woodlands throughout intermountain valleys of Oregon, the San Juan and Gulf islands of Washington and British Columbia, and exposed volcanic scablands of the Columbia Plateau in Washington, Oregon, and northern Nevada. Due to drawdown characteristics, vernal pools typically form concentric rings of similar vegetation. Given their relative isolation in upland-dominated landscapes, many endemic plant species are found in vernal pools. Characteristic species are predominantly annual and diverse. Northern scabland vernal pools share about a third of the species found in northern California vernal pools, but they do not share many of the more common dominant species. Currently very little quantitative plot data have been made available. <i>Eryngium petiolatum</i> and <i>Plagiobothrys figuratus</i> are known dominants that do not occur in California; however, it is assumed many more species could be used to differentiate between these similar groups. Characteristic species in these communities include <i>Callitriche marginata, Callitriche</i> spp., <i>Camissonia tanacetifolia, Deschampsia danthonioides, Downingia elegans, Elatine</i> spp., <i>Eleocharis</i> spp., <i>Epilobium densiflorum, Eryngium petiolatum, Eryngium vaseyi, Grindelia nana, Isoetes orcuttii, Juncus uncialis, Myosurus minimus, Navarretia leucocephala ssp. diffusa, Pilularia americana, Plagiobothrys</i> spp., <i>Plagiobothrys figuratus, Plagiobothrys scouleri, Polyctenium williamsiae, Polygonum polygaloides ssp. confertiflorum, Polygonum polygaloides ssp. polygaloides, Psilocarphus brevissimus, Psilocarphus elatior, Psilocarphus oregonus, Trifolium cyathiferum, Triteleia hyacinthina</i>, and <i>Veronica peregrina</i>. In northern Nevada, most of the species by biomass are perennials and include <i>Carex douglasii, Juncus arcticus ssp. littoralis, Muhlenbergia richardsonis</i>, and species of <i>Eleocharis, Polygonum, Rumex</i>, and <i>Polyctenium</i>. Hardpan vernal pools occur on soils with an indurated clay or cemented (Si or Fe) layer that retains water inputs throughout some portion of the spring, and that typically dry down completely into early summer months. In the Sand Juan and Gulf islands, they are created in small depressions in bedrock. Thus this group only occurs where there is hummocky micro-relief. These wetlands tend to be acidic wetlands. On the Columbia Plateau many pools are located on massive basalt flows, andesite or rhyodacite caprock. Inundation is highly irregular, sometimes not occurring for several years. Depressions usually (but not always) fill with water during winter and spring. They are generally dry again within nine months, though in exceptional times they can remain inundated for two years in a row. Water is from rainfall and snowmelt in relatively small closed basins, on average probably no more than 5-15 times the area of the ponds themselves. Pools are depressions with no outflows. Soils when present are typically silty clay, sometimes with sandy margins. Ponds range from very small (3 sqm) to large depressions (1600 sqm).
Accession Code:
urn:lsid:vegbank.org:commConcept:40210-{5F455B1B-2EFD-431E-A763-81029FB55B90}
Plot-observations of this Community Concept:
0
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