ENVIRONMENTAL PRESERVATION CREDIT SUMMARY

Vernal Marsh

Vernal marsh occurs in association with the sloughs and old, cutoff watercourses of the Elsie Gridley Mitigation Bank. These watercourses drain slowly and therefore tend to remain wet for an extended length of time. This results in emergent plant species adapted to longer period of inundation or saturation such as pale spike-rush (Eleocharis macrostachya), water plantain (Alisma plantago-aquatica), rush (Juncus spp.), and damsonium (Damsonium californicum). Other species present in areas that tend to be in the slightly less wet margins of the wetter areas include perennial ryegrass (Lolium perenne), Mediterranean barley (Hordeum marinum), and coyote thistle (Eryngium vaseyi). Vernal marsh has two distinct phases within the bank lands. One phase closely resembles vernal pools and alkali playa pools. This phase occurs in old cutoff stream channels where standing water persists for extended periods during the winter and spring. Water can be clear/tea-colored to turbid, with water depths ranging up to 3 feet or more. The second phase occurs along the edges of Barker Slough in the floodplain between the emergent marsh zone of the slough and the higher ground uplands/vernal pools/grasslands. This latter phase functions more like the Mesic Grassland/Seasonal Wetland described below.

Species associated with the pooled or ponded water phase of vernal marsh are essentially the same as the alkali playa pools described above and include those species in Group 1 that are associated with vernal pools as well as several species that are typically more restricted to pools with the longer hydro-periods turbid water. Applicable species include Group 1 species plus three additional species:

Group 2 Only Species

• Conservancy fairy shrimp
• Bogg's Lake hedge hyssop
• California tiger salamander (breeding)

Group 1 Species

• Vernal pool fairy shrimp
• Vernal pool tadpole shrimp
• Baker's navarretia
• Dwarf downingia