State 1
Reference

Community 1.1
Black Cottonwood, Oregon Ash, Willow, and Western Swordfern

Structure: Mature deciduous forest with a mix of shrubs in the understory

Black cottonwood, Oregon ash, and red alder are the most dominant overstory species in the reference community (1.1). Douglas-fir and grand fir may also be present, but flooding restricts conifer regeneration. 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.

The reference community (1.1) represents a lack of major flooding for at least 75 years, allowing pioneering species to form a mature canopy. 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: Bare ground with scattered tree, shrub, and grass establishment

This site is a riparian forest undergoing regeneration or stand initiation immediately following flooding disturbance. The soil surface quite often has been scoured or covered by alluvial sediment. Some mature trees maybe present. Some places have increased amounts of downed woody debris. Bare ground permits rapid spread of pioneering species. Relative to conifers, red alder can establish quickly.

Salmonberry, willow, trailing blackberry (Rubus ursinus), and stinging nettle (Urtica dioica) establish during this phase.

Community 1.3
Oregon Ash, Black Cottonwood, Willow, and Stinging Nettle

Structure: Dense single story with diminished understory

This community consists of early seral forest in regeneration that has scattered remnant mature trees in some places. Competition is increased among individual trees for available water, light, and nutrients. Red alder, which has a limited lifespan of 40 to 70 years, initially dominates the overstory. The community shifts to the longer-lived Oregon ash as red alder declines. Shade-tolerant forbs, such as western swordfern, establish during this phase.

Pathway 1.1B
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 may 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.

Pathway 1.3B
Community 1.3 to 1.1

This pathway represents growth over time with active management to maximize timber development. Precommercial thinning, commercial thinning, or both, combined with understory control, lower the stand density and decrease competition for water and nutrients.

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.

State 2
Converted

Community 2.1
Managed Cropland or Hayland

Structure: Annual or perennial non-native species monoculture

Community phase 2.1 can consist of a range of crops, including annually planted species, short-lived perennial species, and more permanent shrubby plants. Hay and grasses and legumes for silage are included in this community phase.

Community 2.2
Non-native Grassland and Shrubland

Structure: Annual or perennial herbaceous or shrubby species

Community phase 2.2 is characterized by low-level agronomic or management activity such as additions of soil nutrients, intensive grazing management, regular mowing, or weed control. This plant community commonly consists dominantly of introduced weedy species. Areas that have extremely low fertility or are subject to heavy grazing pressure have a higher proportion of annual, stoloniferous, or rhizomatous species. Wetland areas commonly support dominantly non-native rhizomatous grasses. The plant community may include remnants of introduced pasture species that commonly are seeded.

Community 2.3
Managed Grassland

Structure: Perennial herbaceous species

Community phase 2.3 receives regular agronomic inputs. Examples include adding soil nutrients and other soil amendments, such as lime; implementing grazing management plans; mowing regularly; controlling weeds; and reseeding as needed. This plant community typically includes introduced perennial pasture and hay species that commonly are seeded. In areas of historic native grassland, mixtures of perennial and annual native species may be seeded and managed by appropriate agronomic and livestock management activities. This phase includes minor amounts of introduced species that commonly are in non-native grassland and shrubland communities (community phase 2.2).

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 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 2.2B
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 represents a change in land use. Land management includes modifications to the hydrologic function to develop pasture and agriculture. Non-native seed disbursement is introduced (intentionally or unintentionally), which alters the reference community (1.1).

Transition T2A
State 2 to 1

This transition represents restoration of the natural hydrologic function and native plant habitat. Native seed sources and extensive management and mitigation of brush and invasive species are needed to restore the community.