State 1
Reference

Lowlands Riparian Forest

Community 1.1
Black cottonwood, Red Alder, Willow, and Western Swordfern

Structure is mature deciduous forest with a mix of shrubs in the understory. Black cottonwood and red alder are the most dominant overstory species in this community. Western hemlock, Douglas-fir, western redcedar, and grand fir may also be present, but periodic major flooding restricts aging of conifers so that they typically do not reach very old age in this ESD, and broadleaved species remain dominant. Conifers are more common further from the active alluvial areas. Regeneration of trees generally is restricted by canopy cover and commonly limited to gaps where sunlight and exposed mineral soil are most available. Community 1.1 represents a lack of major flooding for at least 75 years, allowing pioneering species to form a mature canopy. Black cottonwood is fast growing, and this amount of time allows them to become quite large trees and dominate the overstory. The lack of flooding also permits growth of understory shrubs, including salmonberry, vine maple, stink currant, thimbleberry, and snowberry (Symphoricarpos albus). Common forbs are western swordfern, false lily of the valley (Maianthemum dilatatum), and ladyfern (Athyrium filix-femina). Disturbances include small gap dynamics (1/2-acre openings or smaller) following the decline of the red alder canopy, minor scouring from flooding, and mass movement. Soil deposition following minor scouring from smaller scale and periodic flooding temporarily affects the understory community, but it does not alter the composition of the overstory. Animal activity, such as dam-building by North American beaver (Castor canadensis), can change the hydrology.

Community 1.2
Red Alder, Willow, Trailing Blackberry, and Stinging Nettle

Structure is bare ground with scattered tree, shrub, and grass establishment. This community consists of riparian forest undergoing regeneration or stand initiation immediately following major flooding disturbance. The soil surface quite often has been scoured or covered by alluvial sediment. Some mature trees may be present. Increased amounts of downed woody debris can also be present. Bare ground permits rapid spread of pioneering species. Red alder typically establishes from large numbers of seed very quickly, especially on deposits of finer sediment. Willow (Salix sp) will often establish in abundance from vegetative sprouting of buried stems or roots within areas where alluvial deposits have covered previously rooted willow stems or new stems carried downstream in floodwaters. If Oregon ash is present, it may also establish quickly from vegetative regeneration as underground roots and buried stems may re-sprout. Salmonberry, trailing blackberry (Rubus ursinus), and stinging nettle (Urdica dioica) also establish quickly during this phase.

Community 1.3
Red Alder, Black Cottonwood, Willow, and Stinging Nettle

Structure: Dense single story with diminished understory This community consists of early seral forest with scattered remnant mature trees in places. Competition is increased among individual trees for available water, light, and nutrients. Red alder dominates the overstory and is typically very dense. Because of a limited lifespan of 40 to 70 years, red alder trees will eventually decline and permit more light to penetrate. Black cottonwood is regenerating and beginning to push through the red alder and Oregon ash canopy. Shade tolerant forbs, such as western swordfern, begin to establish during this phase.

Community 1.4
Regenerating Conifer and Broadleaved Riparian Plantation

Structure is single story small trees and shrubs. This community consists of regenerating conifers that have been planted into a young riparian forest or on a riparian site with recent major disturbance. Red alder often regenerates naturally at very high densities, resulting in a dense, young forest. Riparian broadleaved trees, shrubs and mixed herbaceous species typically occupy space between planted saplings. These may include red alder, willow, Oregon ash, black cottonwood, salmon berry, thimbleberry, snowberry, and sword fern, among others. Introduced Himalayan blackberry (Rubus armeniacus) may present, usually at the expense of native shrubs or planted trees. Snags are very few or absent. Downed woody debris may be abundant or limited depending on thoroughness of its reduction during any prior timber harvest.

Community 1.5
Conifer and Broadleaved Riparian Plantation

Structure is single story forest of even-aged trees. This community is the management-controlled climax condition for conifers in this ecological site. The overstory is even-aged and is a mix of conifers and typical riparian broadleaved species. Trees are usually less than 100 years old. The understory is usually relatively well-vegetated with a mix of shrubs, small understory trees and herbaceous species, especially salmon berry, thimbleberry, skunk cabbage, and sedges. Large snags are few or absent.

Pathway 1.1A
Community 1.1 to 1.2

This pathway represents a stand-replacing wildfire, catastrophic windstorm, major 100- or 500-year flood event, or mass movement that scours the stream channel, removes understory and overstory vegetation, and may alter the stream flow. This type of disturbance can completely reconfigure sediment loads and dramatically reduce or eliminate the forest overstory.

Pathway 1.1B
Community 1.1 to 1.4

This pathway represents a stand-replacing wildfire, catastrophic windstorm, major 100- or 500-year flood event, harvest of riparian forest, or mass movement that scours the stream channel, removes understory and overstory vegetation, and may alter the stream flow. This is followed by an effort to replant conifers for a plantation. This type of disturbance can completely reconfigure sediment loads and dramatically reduce or eliminate the forest overstory.

Pathway 1.2A
Community 1.2 to 1.3

This pathway represents growth over time with no further major disturbance. Minor disturbances open space for regeneration of black cottonwood.

Pathway 1.2B
Community 1.2 to 1.4

This pathway represents an effort to establish conifers among the young broadleaved riparian forest. Minor disturbances open space for regeneration of black cottonwood and other regenerating broadleaved species.

Pathway 1.3B
Community 1.3 to 1.1

This pathway represents growth over time with only minor disturbances and overstory alder mortality that opens up space for black cottonwood and conifers to regenerate.

Pathway 1.3A
Community 1.3 to 1.2

This pathway represents a stand-replacing wildfire, catastrophic windstorm, major 100- or 500-year flood event, or mass movement that scours the stream channel, removes understory and overstory vegetation, and may alter the stream flow. This type of disturbance may completely reconfigure sediment loads and dramatically reduce or eliminate the forest overstory.

Pathway 1.3C
Community 1.3 to 1.4

This pathway represents a stand-replacing wildfire, catastrophic windstorm, major 100- or 500-year flood event, timber harvest, or mass movement that scours the stream channel, removes understory and overstory vegetation, and may alter the stream flow. This is followed by an effort to replant conifers for a plantation. This type of disturbance may completely reconfigure sediment loads and dramatically reduce or eliminate the forest overstory.

Pathway 1.4B
Community 1.4 to 1.1

This pathway represents a stand-replacing wildfire, catastrophic windstorm, major 100- or 500-year flood event, or mass movement that scours the stream channel, removes understory and overstory vegetation, and may alter the stream flow. This type of disturbance may completely reconfigure sediment loads and dramatically reduce or eliminate the forest overstory.

Pathway 1.4A
Community 1.4 to 1.5

This pathway represents growth over time with only minor disturbances and overstory alder mortality that opens up space for black cottonwood and conifers to regenerate and ascend to canopy dominance.

Pathway 1.5B
Community 1.5 to 1.1

This pathway represents a stand-replacing wildfire, catastrophic windstorm, major 100- or 500-year flood event, or mass movement that scours the stream channel, removes understory and overstory vegetation, and may alter the stream flow. This type of disturbance may completely reconfigure sediment loads and dramatically reduce or eliminate the forest overstory.

Pathway 1.5A
Community 1.5 to 1.4

This pathway represents a stand-replacing wildfire, catastrophic windstorm, major 100- or 500-year flood event, timber harvest, or mass movement that scours the stream channel, removes understory and overstory vegetation, and may alter the stream flow. This is followed by an effort to replant conifers for a plantation. This type of disturbance may completely reconfigure sediment loads and dramatically reduce or eliminate the forest overstory.

State 2
Deforested

Community 2.1
Cropland or Hayland

Structure: Annual or perennial non-native species monoculture This community phase consists of a range of crops, including annually planted species, short-lived perennial species, and more permanent perennial crops. Hay and grasses and legumes for silage are included in this community.

Community 2.2
Introduced Grass and Shrubs

Structure: Annual or perennial herbaceous or shrubby species Community 2.2 is characterized by low-level or more intermittent management activity such as occasional or light grazing or sporadic mowing. This plant community is dominated by introduced weedy species and the less frequent disturbance supports a shrubbier character with thickets of regenerating broadleaved trees. The site is grazed, mowed or burned often enough to prevent re-establishment of forest. Dominant shrubs are typically invasive rhizomatous species that form thickets such as Himalayan blackberry (Rubus armeniacus). Some tougher native shrub species such as California blackberry (Rubus ursinus) and salmonberry may be interspersed. Areas where ponding or brief inundation occurs commonly support non-native rhizomatous grasses. Between shrub thickets introduced pasture species such as tall fescue (Schedonorus arundinaceus), orchardgrass (Dactylis glomerata), and common velvet grass (Holcus lanatus) are dominant. Alder and black cottonwood are regularly present in seedling thickets or as individual small seedlings.

Community 2.3
Managed Perennial Grassland

Structure is perennial herbaceous species. This community phase is an introduced grassland that receives regular grazing or mowing disturbance and may include soil amendments such as fertilizers or lime. Weeds are aggressively controlled and desired herbaceous species are reseeded as necessary. Grazing, mowing and other weed control actions prevent the phase from transitioning to a forested state. This plant community is typically dominated by introduced perennial pasture species that are seeded after clearing or invade the site from nearby areas. Common species include tall fescue (Schedonorus arundinaceus), orchardgrass (Dactylis glomerata), velvet grass (Holcus lanatus), and red fescue (Festuca rubra).

Pathway 2.1A
Community 2.1 to 2.2

In the absence of agronomic and livestock management activities, seeds from surrounding weedy plant communities are transported to the site by wind, animals, or vehicle traffic, and the adapted species become established. Management activities include tilling; adding soil nutrients and other soil amendments, such as lime; mowing; burning; harvesting or chemically controlling vegetation; planting desirable herbaceous species; and implementing grazing management plans.

Pathway 2.1B
Community 2.1 to 2.3

This pathway occurs by intentional establishment of a perennial grass-dominated plant community. Often, the site will be prepped for seeding and desired pasture species artificially sown. In some cases, simply discontinuing crop production activities may allow the site to transition to grass, provided emergence of woody shrubs or trees is actively controlled with mowing, fire, or chemical treatment. Consistent grazing is essential to the maintenance of this community and to prevent establishment of woody shrubs. Other maintenance practices, such as targeted mowing, prescribed fire, chemical treatment, or other mechanical treatment are utilized as needed.

Pathway 2.2B
Community 2.2 to 2.1

This pathway represents agronomic activities. Examples include tilling; adding soil nutrients and other soil amendments, such as lime; mowing; burning; harvesting or chemically controlling vegetation; and planting desirable crop species.

Pathway 2.2A
Community 2.2 to 2.3

This pathway represents agronomic and livestock management activities. Examples include tilling; adding soil nutrients and other soil amendments, such as lime; mowing; burning; harvesting or chemically controlling vegetation; planting desirable herbaceous species; and implementing grazing management plans.

Pathway 2.3A
Community 2.3 to 2.1

This pathway represents agronomic activities. Examples include tilling; adding soil nutrients and other soil amendments, such as lime; mowing; burning; harvesting or chemically controlling vegetation; and planting desirable crop species.

Pathway 2.3B
Community 2.3 to 2.2

In the absence of agronomic and livestock management activities, seeds from surrounding weedy plant communities are transported to the area by wind, floodwater, animals, or vehicle traffic, and the adapted species become established. Management activities include tilling; adding soil nutrients and other soil amendments, such as lime; mowing; burning; harvesting or chemically controlling vegetation; planting desirable herbaceous species; and implementing grazing management plans.

Transition T1A
State 1 to 2

This transition is caused by an intentional clearing of land or a major disturbance such as a stand replacing fire or major flood in state 1, followed by intense, frequent disturbance such as grazing, mowing, crop production, or frequent fire to prevent trees from re-establishing. This transition can be initiated from any community phase in state 1. Disruption of the hydrologic regime by ditching and draining the site or building levies may or may not occur.

Transition R2A
State 2 to 1

This restoration occurs by artificial or natural re-establishment over time of species resembling overstory and understory diversity typical of the reference state. This transition can be initiated from any community phase in state 2. If the hydrologic regime is intact and flooding can occur regularly, allowing the site to naturally regenerate to shrubs and forest is usually all that is needed. In some cases, treatment of invasive species such as Himalayan blackberry may improve the rate of restoration. If levies or drainage ditches interrupt the hydrologic disturbance process, then removal of ditches, water control structure and levies will be required to restore the reference state.