Natural Resources
Conservation Service
Ecological site AX001X02X001
Mesic Udic Riparian Forest
Last updated: 6/07/2024
Accessed: 12/05/2024
General information
Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 001X–Northern Pacific Coast Range, Foothills, and Valleys
This long and narrow resource area stretches along the Pacific Border Province of the Pacific Mountain System in Oregon and Washington. The area is bounded by the Olympic Mountains on the north and the Klamath Mountains on the south. Most of the area consists of hills and low mountains with gentle to steep slopes. The parent materials are composed primarily of young Tertiary sedimentary rocks with some minor volcanic rocks. Glacial till and outwash deposits are found in the northern half of the area within Washington. In the far southern portion of the area, near the Klamath Mountains, the sedimentary rocks are older and some have been metamorphosed. The average annual precipitation ranges from 60 to 200 inches, increasing with elevation.
The dominant soil orders in this MLRA are Andisols, Inceptisols, and Ultisols. Soil depth ranges from shallow to very deep. While most soils in the area are well drained and occur on foothills, mountain slopes and ridges, floodplain and depressional soils can range from well drained to very poorly drained. Soil textures are typically medial, loamy, or clayey. The dominant soils in the area have a mesic or frigid soil temperature regime and a udic soil moisture regime; however, soils with an aquic soil moisture regime or cryic soil temperature regime do occur.
LRU notes
The North Pacific Coast Range land resource unit (LRU 2) of MLRA 1 is located in the northwestern corner on the Olympic Peninsula and within the Olympic National Forest in Washington State. LRU 2 is bounded on the west by MLRA 4a Sitka Spruce Belt and MLRA 2 Willamette and Puget Sound Valleys to the east. LRU 2 encircles the Olympic National Park (LRU 1). Several major rivers have headwaters in this LRU or carved valleys through the landscape depositing more recent alluvium. These include the Duckabush, Elwha, Queets, Quinault, Skokomish, Sol Duc, and Wynoochee Rivers.
Ecological site concept
This ecological site is found on the western Coast Range on the Olympic Peninsula in Washington state. It is found in riparian corridors on stream terraces and flood plain steps on alluvial soils. It is located at low elevations (less than 1,000 ft.) with abundant precipitation. These areas are subject to stream overflow. Riparian ecological sites typically differ in topography, vegetation, geomorphology, and microclimate from the surrounding uplands of the forest ecosystem (Dwire, 2003).
Conifers such as western hemlock (Tsuga heterophylla), Douglas-fir (Pseudotsuga menziesii), western redcedar (Thuja plicata), and grand fir (Abies grandis) occur in late seral sites or on terraces. Recently disturbed areas are dominated by hardwoods such as black cottonwood (Populus balsamifera ssp. trichocarpa), red alder (Alnus rubra), and bigleaf maple (Acer macrophyllum).
Regeneration is restricted by canopy cover and often limited to gaps where sunlight is most available and mineral soil is exposed from scouring (Pabst, 1999). Understory species diversity is greatest near the streams as a result of erosion and deposition creating openings for opportunistic species as well as the abundance of microsites which create unique environments (Spies, et. al, 2002). Common understory species include willows (Salix spp.), salmonberry (Rubus spectabilis), thimbleberry (Rubus parviflorus), elderberry (Sambucus racemosa), redosier dogwood (Cornus sericea), vine maple (Acer circinatum), western swordfern (Polystichum munitum), ladyfern (Athyrium filix-femina), and Oregon oxalis (Oxalis oregana).
The most common natural disturbance is flooding, with the volume and longevity of the flooding determining the effect on the dynamics of the forest. Although wildfire is uncommon in this ecological site (greater than 450-year return interval) when it does occur, it may be stand replacing (Balian, 2005). Fallen trees with exposed root systems and large woody debris is common.
Associated sites
AX001X02X003 |
Mesic Aquic Forest Mesic Udic Riparian Forest is located adjacent to Mesic Aquic Forest. Mesic Udic Riparian Forest is located on flood plain steps and riparian corridors that are affected by flooding. Mesic Aquic Forest is prone to ponding disturbance. |
---|
Similar sites
AX001X03X001 |
Mesic Udic Riparian Forest This site is similar in ecological function and shares many similar vegetative components. However, this site is located further south in the MLRA and is within LRU C. The presence of Oregon Ash (Fraxinus latifolia) is a strong indicator for LRU C. |
---|
Table 1. Dominant plant species
Tree |
(1) Tsuga heterophylla |
---|---|
Shrub |
(1) Rubus spectabilis |
Herbaceous |
(1) Polystichum munitum |
Legacy ID
F001XB001WA
Click on box and path labels to scroll to the respective text.