|
 |
Myrtle Island Research Natural AreaRoseburg District , BLMCoast Range EcoregionCell(s):
|
Publication: Myrtle Island Research Natural Area Est. Rpt. or Guidelines |
The 11 ha Myrtle Island RNA was established in 1951 to preserve an old-growth stand of California bay laurel (Umbellularia californica) and Douglas fir (Pseudotsuga menziesii). The RNA is located on an island in the Umpqua River west of Sutherlin, in Douglas County, Oregon, where the river flows through a narrow alluvial valley in the interior foothills. The climate is characterized by cool, wet winters and warm, dry summers with an average rainfall of 81 cm per year. Myrtle Island sits at about 100 m elevation, with terraces composed of sandy alluvial soils intermixed with sandstone gravels, cobbles, and stones that change seasonally with floodwater levels. California bay laurel grows on the highest terraces where the soils are deep, loamy sands. The alluvial secondary floodplain terrace is dominated by a community of red alder-Oregon ash/Himalayan blackberry/reed canarygrass (Alnus rubra-Fraxinus latifolia/Rubus armeniacus/Phalaris arundinacea. The west end of the island supports a scrubby, subxeric, open-canopied woodland of Oregon white oak (Quercus garryana) and exotic Scotch broom (Cytisus scoparius). Willow/field horsetail (Salix spp./Equisetum arvense) is the early seral stage plant community following flooding. The vascular flora consists of 363 specific and infraspecific taxa; of these, 226 (62%) are exotics. The major disturbance is seasonal flooding during peak runoffs. A flood during winter 1964-1965 submerged the entire island, causing extensive damage to vegetation, deposition of coarse materials at the western end of the island, and erosion on the southern banks. Older Douglas fir trees bear fire scars.
Access from the north river shore by boat or by wading during summer
Publication: Myrtle Island Research Natural Area Est. Rpt. or Guidelines