State 1
Reference

Western hemlock and Douglas-fir mosaic

Community 1.1
Western Hemlock and Douglas-fir Old Forest

Structure is multistory with many very large, old conifers and intermittent small gaps.

Western hemlock and Douglas-fir dominate this plant community. Other tree species that may occur at lower frequencies in the canopy or sub-canopy include western red cedar, Pacific madrone, grand fir and bigleaf maple. Many dominant overstory conifers are quite old, often exceeding 200 years. Douglas-fir regenerates in the reference community within small gaps created by periodic disturbances that expose mineral soil, while hemlock establishes on both mineral and plant matter substrates, even in deep shade. Douglas-fir’s longevity and great height allow it to persist for centuries without disturbance, if it can attain a dominant canopy position in canopy gaps. Large Douglas-firs resist and survive low to moderate intensity fire with thick bark and canopy crown fuels held very high above the forest floor. Armillaria root rot can be a locally common disease. It can kill young hemlocks and Douglas-firs and weaken older trees, leaving them susceptible to windthrow and insect attacks. The small openings created by the death of one or several trees allow sunlight into the understory, benefiting shrubs and forbs and releasing advanced tree regeneration.

Western hemlock is also prone to other types of root rot. Pockets of dead and dying trees can extend for several acres, allowing enough sunlight for the regeneration of less shade-tolerant species. Storm events and infrequent low to moderate intensity fires also cause minor openings and soil exposure that provides a pathway for regeneration of many species which persist in this reference state by occupying these small openings before trees overtake them.

Community 1.2
Mixed Regeneration

Structure is dense conifer seedlings and resprouting hardwoods among a thick native shrub layer, beneath many large snags.

This community consists of a mix of regenerating trees, shrubs, forbs and grasses over a large area that has recently experienced a significant overstory tree mortality event, usually high severity fire. Snags and other large woody debris are abundant. Species composition is diverse, with young trees representing pre-fire dominant species of western hemlock and Douglas-fir, and occasionally western red cedar. Many shrub and herbaceous species have increased or expanded opportunistically; some species that were not apparent prior to the disturbance may regenerate from persistent seed banks. Vegetation is often very dense and vigorous, and most species exhibit accelerated growth in the high light conditions. Shrub growth response is emblematic of many species’ ability to resprout from the root collar, rhizomes, or shallow subsurface roots. If present, big leaf maple and madrone will also regenerate by resprouting from the root collar of burned stems with rapid initial growth of many sprouts from each surviving parent stump. This resprouting mix will typically dominate while young conifer trees have yet to emerge above this tall shrub layer. Shrubs often include salal, oceanspray and red huckleberry. If introduced to the site, non-native Himalayan blackberry (Rubus armeniacus) and Scotch broom (Cytisus scoparius) may become abundant in this phase, usually at the expense of native shrubs and trees. A rich mix of herbaceous species are typically present.

Community 1.3
Western Hemlock and Douglas-Fir Canopy Closure

Structure is single story of pole to medium sized conifers with diminished understory, infrequent small gaps, frequent large snags.

This community typically consists of a forest undergoing canopy closure from natural regeneration. Western Hemlock and Douglas-fir has overcome early shrub dominance across much of the forest by forcing its way through gaps in shrub cover or occupying space opened up by successive minor disturbances. Western red ceder is occasionally present as a sub-dominant canopy tree, persisting despite heavy side-shading from adjacent hemlock and Douglas-fir. If present, re-sprouting bigleaf maple has now overtopped the shrub layer and often exhibits a multi-stemmed tree form in a co-dominant canopy position and will sometimes dominate the canopy in large patches where conifer regeneration was less abundant or where they have not yet grown through the canopy. With canopy closure, competition for sunlight has led to a diminished understory that favors more shade tolerant species such as red huckleberry, swordfern and salal. Other shrub species resembling the composition typical of the previous early seral re-sprouting forest phase are limited to infrequent small gaps in the canopy where conifers were not able to establish. Tree density is variable, but there is minimal vertical overstory differentiation due to the tree layer being relatively even aged. The herbaceous component is limited but present.

Community 1.4
Maturing Western Hemlock and Douglas-fir

Structure is single story with canopy that is beginning to thin.

This community consists of maturing western hemlock and Douglas-fir dominated forest. Western red cedar may be present in the overstory but has largely been forced into a subdominant canopy position by the increasing height of Douglas-fir and western hemlock. Conifers are now also overtaking bigleaf maple as they grow through and above maple crowns. The forest canopy is now fully closed, and the stand is starting to differentiate vertically, becoming more complex as some trees are suppressed and die and the canopy has lifted high above the forest floor resulting in a more open understory. A mix of shrubs and herbs has persisted in the understory and some species that do well with dappled light, such as red huckleberry, are expanding. Shade tolerant species also perform well, such as salal and western swordfern. Herbaceous species typical of the reference western hemlock and Douglas-fir old forest phase have begun to reappear.

Pathway 1.1A
Community 1.1 to 1.2

This pathway occurs from a stand-replacing fire in which all or nearly all overstory trees are killed.

Pathway 1.2A
Community 1.2 to 1.3

This pathway represents growth over time with only very minor or no additional disturbances.

Pathway 1.3B
Community 1.3 to 1.2

This pathway occurs from a stand-replacing fire in which all or nearly all overstory trees are killed.

Pathway 1.3A
Community 1.3 to 1.4

This pathway represents growth over time. Minor disturbances may occur without disrupting this pathway, such as low-intensity fires, understory fuels management, pockets of pests or disease, and damage from weather events. These may help accelerate advancement toward Pathway 1.4a by opening space for more understory species and creating more structural complexity.

Pathway 1.4A
Community 1.4 to 1.1

This pathway represents growth over time and a mix of minor disturbances. Minor disturbances play an important role in this pathway, and may include low to moderate-intensity fires, understory fuels management, pockets of pests or disease, and damage or mortality from weather events. These disturbances create new canopy gaps that facilitate tree regeneration, open space for more understory species and create more structural complexity.

Pathway 1.4B
Community 1.4 to 1.2

This pathway occurs from a stand-replacing fire in which all or nearly all overstory trees are killed.

State 2
Timber Plantation

Community 2.1
Mature Western Hemlock and Douglas-fir Plantation

Structure is single story forest of even-aged trees.

This community is the management-controlled climax condition for a Western Hemlock and Douglas-fir plantation. The overstory is even-aged and exclusively or near exclusively Douglas-fir and hemlock. Trees are usually less than 100 years old. Trees are relatively evenly spaced, owing to their having been artificially established on a tight grid; there are typically no significant canopy gaps and little complexity in canopy structure. Stock used for planting is often skewed to more heavily favor Douglas-fir as it is typically of greater value than western hemlock; though western hemlock may regenerate readily in the shaded understory. Western red cedar may be included in planting or occur naturally from adjacent seed sources depending on management objectives. Hardwoods such as maple are typically less abundant due to efforts to control them and increase space for and growth of desired conifers. The understory may be somewhat sparse to relatively well-vegetated with a mix of highly shade-tolerant shrubs and herbaceous species, especially western sword fern or salal (Gaultheria shallon). Large snags are very few or absent.

Community 2.2
Regenerating Western Hemlock and Douglas-fir Plantation

Structure is single story small trees and shrub.

This community consists of regenerating conifer forest over a large area that has been opened by timber harvest. Species composition is strongly controlled by management actions. The site is typically planted with Douglas-fir, and lesser amounts of western hemlock and western red cedar. Non-timber shrubs and trees are controlled to facilitate planted seedling survival, resulting in a dense, young conifer forest. Shrubs and mixed herbaceous species typically occupy space between planted saplings. These may include oceanspray, salal, red huckleberry, western sword fern and salmonberry. Introduced Himalayan blackberry (Rubus armeniacus) and Scotch broom (Cytisus scoparius) are often present and may be abundant, 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 the prior timber harvest.

Community 2.3
Stem Exclusion Western Hemlock and Douglas-fir Plantation

Structure is perennial herbaceous species.

This community is the interim point in a Douglas-fir and western hemlock plantation between regeneration and the mature state. Composition is exclusively or near exclusively Douglas-fir and western hemlock, and the stand is very dense, having been artificially established on a grid and tended with weed control methods to maximize conifer survival. Western red cedar is often present at a lower frequency. A pre-commercial thin is may be applied at or shortly before this phase to reduce inter-tree competition and maintain high growth rates. The understory is often very sparse, particularly if pre-commercial thinning is not performed, owing to the very limited light that reaches the forest floor. Only highly shade tolerant species occur, if present at all. Snags are very few or absent. Downed woody debris may be abundant or limited depending on thoroughness of its reduction during the prior timber harvest.

Pathway 2.1A
Community 2.1 to 2.2

This pathway represents even-aged harvest of a mature western hemlock and Douglas-fir plantation followed by conifer planting. This pathway may also result from a stand-replacing fire followed by a salvage harvest and replanting. Site preparation and removal of woody material to limit fire hazard is usually performed prior to planting.

Pathway 2.2A
Community 2.2 to 2.3

This pathway represents growth of an even-aged western hemlock and Douglas-fir plantation alongside active weed controls to limit competition with undesired species. Thinning of conifer saplings and pruning may or may not occur, depending on stand density or fire hazard concerns. Disturbances, such as fire, pests, and disease, are discouraged and controlled if possible.

Pathway 2.3A
Community 2.3 to 2.1

This pathway represents growth of an even-aged western hemlock and Douglas-fir plantation that is maturing and dominates the overstory. Light thinning may or may not occur, depending on stand density or fire hazard concerns. Disturbances, such as fire, pests, and disease, are discouraged and controlled if possible.

Pathway 2.3B
Community 2.3 to 2.2

This pathway results from a stand-replacing fire or a major pest or disease event that kills all or nearly all trees, followed by replanting of conifers. Salvage harvesting may occur if there is sufficient commercially viable material in the stand. Site preparation and removal of woody material to limit fire hazard is usually performed prior to planting.

State 3
Deforested

Community 3.1
Cropland or Hayland

Structure is annual or perennial non-native species monoculture.
This community 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 3.2
Introduced Grass and Shrubs

Structure is annual or perennial herbaceous or shrubby species.
Community 3.2 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 more shrubby character. 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) or those that develop a robust seedbank and flourish in open conditions such as Scotch broom (Cytisus scoparius). Some tougher native shrub species such as California blackberry (Rubus ursinus) 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), redtop (Agrostis gigantea) and red fescue (Festuca rubra) are common. Fire and soil disturbing activities often favors an increase in western brackenfern (Pteridium aquilinum).

Community 3.3
Managed Perennial Grassland

Structure is perennial herbaceous species.
This community 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. Common species include tall fescue (Schedonorus arundinaceus), orchardgrass (Dactylis glomerata), redtop (Agrostis gigantea), and red fescue (Festuca rubra).

Pathway 3.1A
Community 3.1 to 3.2

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 3.1B
Community 3.1 to 3.3

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 3.2B
Community 3.2 to 3.1

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 3.2A
Community 3.2 to 3.3

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 3.3A
Community 3.3 to 3.1

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 3.3B
Community 3.3 to 3.2

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 shift to a Douglas-fir and western hemlock timber plantation management system. This transition is typically initiated by clear cut of old forest in the reference state but can be initiated after a large stand-replacing fire in the reference state. Management actions include even-aged harvests and replanting of evenly spaced Douglas-fir. Other tree species, especially non-conifers such as madrone and maple, are heavily controlled to promote maximum dominance and growth of Douglas-fir.

Transition T1B
State 1 to 3

This transition is caused by an intentional clearing of land or a stand replacing fire 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.

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

Transition T2A
State 2 to 3

This transition is caused by an intentional clearing of land or a stand replacing fire in state 2, 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 2.

Restoration pathway R3A
State 3 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. Intentional planting, site preparation, and control of competing invasive weeds will accelerate this transition. This transition can be initiated from any community phase in state 3

Restoration pathway T3A
State 3 to 2

This transition occurs with a change in land management from a cleared non-forest state to a Douglas-fir plantation. The site is typically treated mechanically or with fire to prep the seed bed before planting Douglas-fir on an even spacing. Competing species are heavily controlled to improve seedling survival and growth. This transition can be initiated from any community phase in state 3.