Inventory of lichen and bryophyte communities in the Yeon Unit of Lewis and Clark National Historical Park: Final report

Siskiyou BioSurvey, LLC

doi:10.36967/2301457

The 106-acre Yeon Unit of Lewis and Clark National Historic Park lies along the immediate coast eight miles north of Seaside, Oregon. The primary objective of these surveys was to capture the complete lichen and bryophyte flora of the Yeon property with focus on the remnant prairies and the salix swamp, report on any rare species observed or collected, and document the extent and population size of the rare lichen, Pannaria rubiginosa. Surveys were conducted in December 2021 and January 2022. While this report sufficiently characterizes the lichen and bryophyte flora of the Yeon property, it is not sufficient for the Sunset property. For a complete list of the non-vascular flora of the Sunset property, a more intentional survey should be conducted. Of the 46 bryophyte species recorded, none of them are considered rare by ORBIC. The species checklist reflects a bryoflora typical of Pacific Northwest coastal dune ecosystems. The collection of Dicranum rhabdocarpum needs to be verified as it is rare in Oregon and there is low confidence in the species level determination of it. The invasive moss, Camplylopus introflexus, was found throughout the site in impacted areas especially where fire management had been conducted. This moss should be monitored as it has spread throughout most areas of the dune and may displace native bryophytes and complicate ecological succession in fire/restoration areas. Lichens were found throughout the 106-acre Yeon unit, although in varying density and diversity. The fore dunes adjacent to the open sand area of the coast historically hosted the coastal prairie habitat but now this area was almost completely infested with the invasive beachgrasses Ammophila arenaria and A. breviligulata. In this area these xerophytic Ammophila species occupied nearly 100% of the terrestrial habitat and there were no trees or shrubs to provide arboreal lichen habitat. There were a few small patches of remnant prairie within the swaths of Ammophila spp. that were generally smaller than 10m². In these areas the lichens were dominated by Cladonia, Peltigera and Scytinium species. In general, the shore pine habitat that has not been recently thinned had a dense canopy and therefore the surveyable lichen habitat had very low rates of lichen colonization. The exceptions were the areas with edge effects. The west side facing the foredunes hosted a few arboreal species. Light gaps within this forest had minimal arboreal and terrestrial species colonization. Thinned shore pine plantations had a slightly higher concentration of species richness and increased biomass due to the abundance of light that penetrates to the surveyable habitat. These were limited to fairly common species in genera such as Hypogymnia, Platismatia, and Usnea. The area with the richest lichen diversity was in the interdunal wetland and willow swamp areas. These habitats had rich and well developed cyanolichen communities.

Inventory of lichen and bryophyte communities in the Yeon Unit of Lewis and Clark National Historical Park: Final report

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