Ecological dynamics
Western hemlock and western redcedar are the dominant trees. Douglas-fir grows in places, but it is not shade tolerant compared to western hemlock and western redcedar (Thuja plicata). Because it is such a long-lived species (800+ years), however, scattered individuals remain. Bigleaf maple (Acer macrophyllum) and red alder may also be present.
Most areas of this site have been harvested for timber since European settlement. Although the areas were typically burned after harvest, all of the various plant communities can have remnant mature trees. The historic fire regime had low frequency (150 to 300+ years) and moderate to high intensity. These fires would, in effect, be stand-replacing. Individual trees, however, would survive and provide a seed source. Western hemlock, which has thin bark and a shallow root system, is not able to tolerate fire. Western redcedar is only somewhat more tolerant. Douglas-fir is well adapted to withstand fire; therefore, even moderate fire is likely to change the species composition.
Red alder is a common early-seral, fast growing species in this area. It commonly seeds-in on newly cleared land. This typically results in a nearly pure stand that includes a scattered number of Douglas-fir, redcedar, and hemlock. Red alder, however, is shade intolerant and cannot reproduce under its own canopy. It is also relatively short-lived. The stand starts to deteriorate after about 70 years. This deterioration releases the more shade-tolerant species that seeded in under the alder. The stand then progresses toward the reference community phase until the next disturbance.
If no red alder seed source is available, the initial stand is a mix of western hemlock, western redcedar and Douglas-fir. The most common natural disturbances in areas of this site are small pockets of wind-thrown or diseased overstory trees. All three of these species are susceptible to various rots, which weaken the roots and boles and cause breakage. The resulting openings in the canopy allow some sunlight to reach the forest floor, which benefits the commonly sparse understory. Openings are especially likely in mid-successional (75 to 150 year old) stands, which have very little height differentiation. Western swordfern (Polystichum munitum), red huckleberry (Vaccinium parvifolium), salal (Gaultheria shallon), trailing blackberry (Rubus ursinus), and Cascade barberry (Mahonia nervosa, known locally as Cascade Oregongrape) are common understory species in this ecological site.
Community 1.1
Western Hemlock, Western Redcedar, Red Huckleberry, Salal, and Western Swordfern
Structure: Multistory with small gap dynamics
Western hemlock and western redcedar are the most common overstory species. Douglas-fir and bigleaf maple are also present. The dense canopy, which is created by multiple age groups of hemlocks, blocks most of the sunlight from the forest floor and leads to a sparse understory. The majority of the understory plants grow where gaps in the canopy allow sunlight to reach the ground. In areas where there is no mid-canopy of regenerating hemlocks, the understory is more continuous. The most common natural disturbance in areas of this community are the small gap dynamics following the death of one or two trees.
Community 1.2
Western Hemlock, Douglas-fir, Red Huckleberry, Salal, and Western Swordfern
Structure: Mosaic of mature overstory and regenerating openings
This community phase retains some areas that resemble the reference community but also contains moderate sized (2–5 acres) openings. Historically, this spatial pattern would have been caused by low- to moderate-intensity fires or pockets of disease (such as annosum root rot or laminated root rot). Uneven-aged management techniques, such as group selection or shelterwood with reserves, can also create this plant community.
Depending on the seed sources present, the patches may contain any of the previously mentioned overstory species. Some of the shrub species in the ecological site also respond well to increased sunlight and may delay or even prevent reforestation of the newly formed openings. Examples include Cascade barberry (Mahonia nervosa, known locally as Cascade Oregongrape), salal, salmonberry (Rubus spectabilis), and red elderberry (Sambucus racemosa).
Community 1.3
Douglas-fir, Red Alder, Western Hemlock, and Salal
Structure: Single story/shrub
This community consists of forestland in regeneration. Species composition depends on the natural seed sources present and the intensity of management. If this community results from a moderate to severe fire event, the possibility is good for shrubs to out-compete tree seedlings. Red huckleberry, salal, trailing blackberry, red elderberry, and salmonberry (which may have been only moderately abundant previously) all have the capability to rapidly recover and spread when top-killed, slowing successful regeneration. This would be less of an issue with intensive management. Historically, Douglas-fir has been preferred over red alder, western redcedar, or western hemlock on these sites. This has changed over time, so a managed stand could feature any of the species or a mixture of species.
Community 1.4
Douglas-fir, Red Alder, Western Hemlock, Salal, and Western Swordfern
Structure: Dense single story with sparse understory
This community consists of forest in the competitive exclusion stage. Because this community is indicative of no active management, competition among individual trees is increased for the available water and nutrients. Canopy closure is almost 100 percent, leading to a diminished understory. Over time, the forest begins to self-thin due to the elevated competition. Species composition depends on the original seed source(s) available. The forest can be single or mixed-species.
Community 1.5
Douglas-fir, Western Hemlock Red Alder, Salal, Red Huckleberry, and Western Swordfern
Structure: Single story with scattered openings
This community consists of maturing forest that is starting to differentiate vertically. Individual trees are dying (due to insects, disease, competition, or windthrow), allowing some sunlight to reach the forest floor. The sunlight allows for an increase in the understory as well as some overstory tree species regeneration. Cycling between Community Phases 1.3 and 1.5 while using even-aged management generates maximum wood fiber.
Pathway 1.1A
Community 1.1 to 1.2
This pathway represents a large disturbance. Historically, a moderate-intensity fire or windstorm would have created this forest structure. Uneven-aged management techniques, such as group selection or shelterwood with reserves, can also lead to this community. Areas of regeneration range from 2 to 5 acres.
Pathway 1.1B
Community 1.1 to 1.3
This pathway represents a major disturbance, such as a high-intensity fire, large scale wind events, or clear-cutting followed by prescribed burning.
Pathway 1.2A
Community 1.2 to 1.1
This pathway represents growth over time with no further significant disturbance. The areas of regeneration pass through the typical stand phases—competitive exclusion, maturation, and understory reinitiation—until they resemble the old-growth structure of the reference community (1.1).
Pathway 1.2B
Community 1.2 to 1.3
This pathway represents either a high-intensity fire or a change to intensive management (block harvest, post-harvest burn). Both situations lead to the stand initiation phase of forest development.
Pathway 1.3B
Community 1.3 to 1.4
This pathway represents no further management, denoting only growth over time.
Pathway 1.3A
Community 1.3 to 1.5
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 1.4A
Community 1.4 to 1.5
This pathway represents grow over time, with or without active management. Precommercial (or possibly commercial) thinning can decrease competition by removing a portion of the trees. Without management, intermediate and suppressed trees begin to die.
Pathway 1.5A
Community 1.5 to 1.1
Douglas-fir, Western Hemlock Red Alder, Salal, Red Huckleberry, and Western Swordfern
Western Hemlock, Western Redcedar, Red Huckleberry, Salal, and Western Swordfern
This pathway represents no further management. Continued growth over time and ongoing mortality lead to continued vertical diversification. The community begins to resemble the structure of the reference community but has small pockets of regeneration and a more diversified understory.
Pathway 1.5B
Community 1.5 to 1.3
This pathway represents intensive management focused on wood products. Clear-cutting, some type of site preparation, planting of preferred species, and timely thinning are the management steps.
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 the addition 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 can 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.
