Red Alder (Alnus rubra)

Oregon alder, western alder, Pacific coast alderAlder Leaf

This information was originally published in Hardwoods of the Pacific Northwest, S.S. Niemiec, G.R. Ahrens, S. Willits, and D.E. Hibbs. 1995. Research Contribution 8. Oregon State University, Forest Research Laboratory

General Characteristics

Alders are members of the birch family (Betulaceae). Of the ten species of Alnus native to the United States, red alder is the only one that reaches commercial size and abundance. It is also the most common and important of the hardwoods in the Pacific Northwest.

Alder rangeSize, Longevity, and Form
Mature red alder trees are typically 70 to 120 ft in height (130 ft maximum) and 10 to 34 in. in diameter (70 in. maximum). Red alder are mature at 60 to 70 years; they seldom survive beyond 100 years. In forest stands, red alder develops a clear (60 to 70 percent of total height), slightly tapered bole with a narrow, domelike crown. Open-grown trees form broadly conical crowns and highly tapered boles, often with large forks and branches. The root system of red alder is shallow and spreading where limited by poor drainage; a deep-root system develops on soils with better drainage.

Geographic Range
The range of red alder extends from southeastern Alaska (lat 60°N) to southern California (lat 34°N), generally within 125 miles of the ocean. Red alder is common at low elevations throughout the Coast and north Cascade ranges but is restricted to riparian areas or moist microsites farther south.

Timber Inventory
Historical inventories indicate that the abundance of red alder has increased about 20-fold since the 1920s, though this trend may be reversed by modern forest practices, which favor conifers. The current inventory of about 7.4 billion cubic feet of red alder comprises 60 percent of the total hardwood volume in the Northwest (Appendix 1, Table 1). The greatest volume occurs in the Puget Sound and Northwest Oregon subregions. A significant portion of the red alder resource is not available for harvest; forest practices rules constrain timber management in riparian areas where red alder is most abundant. Also, very little red alder is sold from public lands, although substantial inventory occurs there.

Biology and Management

Tolerance, Crown Position
Red alder is intolerant of shade, and it must maintain a dominant or codominant canopy position. Trees of intermediate or suppressed-crown classes do not survive long. Both pure and mixed-species stands are predominantly even-aged. In mixed stands, red alder are usually grouped.

Ecological Role
Red alder is a pioneer species that establishes rapidly in openings created by forest disturbance; it commonly invades newly bared soils after landslides, logging, or fire. Red alder can maintain or improve soils via rapid input of organic matter and nitrogen. Its roots fix atmospheric nitrogen via symbiosis with the actinomycete, Frankia. Red alder does not reproduce in the absence of soil disturbance.

Associated Vegetation
Red alder often occurs in mixture with other tree species. Common associates include Douglas-fir, western redcedar, western hemlock, grand fir, Sitka spruce, bigleaf maple, vine maple, black cottonwood, Pacific willow, and bitter cherry. Common shrubs and herbs associated with red alder are salmonberry, thimbleberry, red elderberry, devil’s-club, whortleberry, osoberry, evergreen blackberry, western swordfern, and hedge nettle.

Suitability and Productivity of Sites
The suitability of specific sites should be carefully assessed before red alder management is planned. Although red alder colonizes a wide variety of sites, many of those sites present high risks of tree mortality, persistent damage, or poor growth and are thus unsuitable for timber management. Good sites for red alder are generally found along streams, in moist bottomlands, and on lower slopes. Growth of red alder can also be quite good on upland sites (below 2000 ft) with adequate soil moisture and a favorable climate.

When representative red alder trees are present, site index should be estimated with either the 20-year base age (Harrington and Curtis 1985) or the 50-year base age (Worthington et al. 1960). Harrington’s 1986 study, “A method of site quality evaluation for red alder,” should be used for evaluating a site when there are no representative red alder present.

Climate
The typical climate in the range of red alder is mild and humid. Most precipitation occurs as rain in the winter; summers are generally cool and dry. Better red alder sites receive occasional rain and frequent morning fog during the summer. Annual precipitation ranges from 16 to 220 in. (405 to 5600 mm) and temperatures range from -22 to 115° F (-30 to 46.1° C).

For red alder, risks of excessive mortality and damage from sunscald, heat, or drought are high on southerly aspects, particularly inland on steep slopes. Planted red alder seedlings are particularly susceptible. Near the coast, higher humidity and soil moisture provide more favorable conditions on any aspect. Good development of trees occurs where annual precipitation exceeds 40 in. or where roots have access to ground water. Red alder do poorly under droughty conditions, which may result from inadequate annual or seasonal precipitation, low moisture-holding capacity of the soil, or high evapotranspiration, together or singly.

Severe freezing or unseasonable frost hazards can greatly limit management of red alder. Local frost pockets and flat areas that accumulate cold air from large, cold-air drainages are poor sites for red alder. Both late spring and early fall frost can be disastrous to young plantations. Cumulative effects of periodic frosts produce poor quality stands.

Periodic exposure to high winds can greatly reduce stem quality and height growth of red alder. Areas exposed to periodic high winds (>50 mph) and coastal sites that are not protected from prevailing winds should be avoided.

Elevation
Management of red alder should generally be restricted to elevations below 3000 ft at the southern end and 1000 ft at the northern end of red alder’s range.

Soils
Although red alder is found on a wide range of soils, the most productive stands occur on deep, well-drained loams and sandy loams derived from marine sediments or alluvium. There are also good red alder sites on soils of volcanic origin. Plentiful soil moisture during the growing season is necessary for good development of red alder. Excessive drought is produced by soils with low water-holding capacity including coarse-textured soils (sandy loams or sands) or soils with high rock fragment contents (>40 percent by volume). Coarse soils with consistent subsurface moisture (flood plains, riparian areas) are acceptable, although drought hazards are still high during stand establishment, particularly if competing vegetation is present.

Red alder tolerates poor drainage and occasional flooding during the growing season. Sites with very poor drainage or sites subject to prolonged flooding during any season are not suitable for management of red alder plantations.

Soils low in available phosphorus (P) greatly limit establishment and growth of red alder, although specific criteria for determining deficiency of P in soils have not been developed for red alder. Deficiency of P in red alder is indicated by foliar concentrations of less than 0.16 percent. Deficiency of soil nitrogen (N) is of lesser concern for red alder. Nitrogen fixation via red alder’s symbiotic association with Frankia can compensate for deficiencies in soil N.

Flowering & Fruiting
Trees reach sexual maturity as early as 3 to 4 years of age. Dominant trees in a stand usually begin to produce seed at 6 to 8 years of age. Red alder is monoecious, having separate male and female flowers on the same individual. Male catkins develop in clumps that hang down. In late winter, they elongate from 1 to 3 in. and turn from green to reddish-brown, releasing their pollen in late winter and early spring. Female flowers are borne in clumps of upright catkins, which later develop into cone-like strobiles that bear the seed. The “cones” begin to ripen in September or October, changing from green to yellow-green or brownish-green to brown.

Seed
The seeds are small, winged nutlets borne in pairs at the base of bracts within the strobiles. Seeds are very light (350,000 to 1,400,000 seeds/lb) and they can be carried long distances by the wind. Seed dispersal may begin in late September; most seeds are released from late fall through winter. Seed should be collected from a local source to ensure that seedlings are adapted to conditions on the outplanting site. Cones should be collected from numerous trees of good growth and form that are well distributed within a stand. The quality and quantity of the cone crop should be assessed in July or August. Collection of cones may begin when the color of a cone has changed to about 50 percent yellow. Another test for crop maturity is to twist cones along the long axis. Seeds are ripe if the cone twists easily and the bracts separate.

After collection, cones should be airdried in paper or cloth bags. Care must be taken to provide adequate ventilation and prevent molding. When cones have dried, seed should be extracted via thrashing in a tumbler or by hand (for small lots). Yield may be increased by repeated wetting, redrying, and extracting. Extracted seeds are screened to remove large debris. Air column machines can be used to remove small trash and empty seed. For short-term storage, dry seed can be stored in sealed containers in the refrigerator with no loss in viability. Red alder seed may be stored for 5 to 10 years with little loss in viability when dried to less than 10 percent moisture content (MC) and stored in sealed containers in the freezer.

Regeneration from Seed
Dissemination of light red alder seed by the wind commonly produces widespread colonization on disturbed soils under a variety of conditions. Very little work has been done to develop methods of intentional regeneration of red alder from seed, however. Establishment from seed generally requires open conditions and bare mineral soil; red alder seedlings become established on organic substrates only under very moist conditions. Excessive heating or drying of the soil surface at any time greatly limits establishment of red alder from seed.

High humidity and soil moisture near the coast or at the north end of red alder’s range provide favorable conditions on almost any aspect. In the interior Coast Range or Cascade foothills, establishment from seed is practically zero on southern aspects, and it may be limited to wet microsites and lower slopes on northern aspects.

Adequate distribution of seeds can be provided by well-distributed seed trees or a seed “wall” adjacent to the selected unit. Smaller clearings (less than 20 acres) with a seed source on at least two sides can regenerate well. Isolated seed trees left after harvest may not stand very long. Seed trees on the north side of a unit are preferable, since dispersal is accomplished primarily by drying north winds in the late fall and winter.

Conditions favorable for natural regeneration of red alder often produce an overabundance of seedlings (exceeding 100,000 stems per acre), and early precommercial thinning may be necessary to prevent stagnation or poor growth.

Regeneration from Vegetative Sprouts
Young red alder will sprout vigorously after cutting (coppicing). Coppices with rotations of 4 to 6 years have been managed successfully for a few rotations. Red alders more than 10 years old do not sprout well after cutting; regenerating red alder by coppicing older stands is not feasible.

Red alder are not easily established from unrooted cuttings. Cuttings of greenwood from young trees can be rooted by dipping in indole-3-butyric acid and culturing in a warm, well-aerated medium. Tests of operational regeneration from rooted cuttings have been minimal.

Regeneration from Planting
Planting of seedlings allows greater flexibility in site selection and provides greater control over spacing and seed source compared to regeneration from seed. Vigorous, planted red alder seedlings will have an advantage over competing vegetation. Seedlings of good quality, planted on well-prepared sites can reach heights of 4 to 7 ft after the first growing season.

Plantations of red alder can be successfully established with a variety of seedling stocktypes, but many efforts have failed because of poor quality seedlings, extreme weather, and other hazards. Consistent success requires a careful evaluation of regeneration hazards, along with adequate seedling quality, and good site-preparation and planting practices. Red alder seedlings that will have the best survival rate, growth rate, and resistance to damage over a range of conditions are characterized as follows:

Height of 12 to 36 in. and basal diameter (caliper) of at least 0.16 in. (4 mm) Stocky, rather than tall and thin Healthy buds or branches along the entire length of the stem, particularly the basal portion Full, undamaged fibrous root systems Free of disease.

Site Preparation and Vegetative Management
Vigorous red alder seedlings can compete successfully with little or no site preparation when levels of competing vegetation are low to moderate. Moderate amounts of slash, debris, and vegetation shelter new seedlings and may also improve establishment. With high levels of competing vegetation, site preparation is required to achieve adequate stocking and good performance. Growth of red alder seedlings may be lower if the cover of competing vegetation exceeds 90 percent during the first year. Survival may be reduced by competition from 125 to 150 percent cover with overtopping in the first year.

Broadcast burning often provides adequate site preparation where levels of slash and/or shrub cover are high. Chemical site preparation may be most cost-effective for controlling both shrubby and herbaceous competitors. When a site has been heavily invaded by herbs, herbicide treatments just before planting can make the difference between success and failure of hardwoods.

When regeneration is directly from seed, site preparation should produce an even distribution of bare mineral soil. Mechanical scarification, broadcast burning, or piling and burning will do this in most situations. To prevent overabundant regeneration, one method is to minimize soil disturbance during harvest and then mechanically scalp evenly spaced spots throughout the unit. Closely spaced red alder seedlings (less than 9 ft) can effectively dominate a site within 2 to 4 years, thereafter, site-preparation treatments are unnecessary. Red alder at wider spacings (10 to 20 ft) are vulnerable to the prolonged effects of vegetative competition. At these wider spacings, maintenance of weed-free conditions after establishment can double to quadruple seedlings’ growth in comparison to unweeded trees.

Stand Management
Natural stands of red alder generally establish at high densities (10,000 to 100,000 stems per acre); intense competition causes rapid self-thinning and slow diameter growth. Management of lower initial densities (300 to 600 stems per acre) can increase diameter growth rates on crop trees 15 to 20 percent compared to unmanaged stands during the first 15 years. Continued thinning (pulpwood, fuelwood, precommercial thinning) can maintain diameter growth rates up to 30 percent higher than those in unmanaged stands, at least until age 25. Managed stands are expected to attain an average diameter of 12 in. by age 30 or before; the average natural stand would take 45 years (SI50 = 100 ft).

Guidelines for management of stand density are provided by the density management diagram (Puettmann et al. 1993). Thinning must favor trees with good growth potential (dominant or codominant trees less than 15 to 20 years old). It is not worthwhile to thin older stands or to leave suppressed trees because the remaining trees will not have adequate capacity for growth response.

Some crowding is necessary to maintain dominance of red alder and to reduce branching, forking, and stem taper. The goal is to manage spacings that optimize growth while maintaining the benefits of crowding. Moderate crowding will induce lower branch mortality with minimal reductions in diameter growth. Relatively uniform spacing in managed stands will also improve stem form by producing straighter stems. Red alder grow towards the light; clumpy spacing and large holes in the stand increase lean and sweep.

Initial spacings of 9 to 10 ft between trees should shade out lower branches 30 to 40 ft up the bole by ages 8 to 15 years. A subsequent thinning, combined with pruning of dead branches (many are broken off during thinning) will maintain diameter growth on a high-quality bole. Pruning of live branches may also increase wood quality, although little work has been done on this.

Mixed-species Stands
Because of red alder’s ability to improve soils via N-fixation and addition of organic matter, there is particular interest in managing red alder in mixture with conifers in order to maintain or improve site productivity. Management of mixtures can be difficult because of red alder’s rapid height growth and great sensitivity to competition. Under favorable moisture conditions, red alder will overtop and suppress conifers established at the same time. Low proportions of red alder may be difficult to maintain over the long term, because red alder must maintain codominance in order to thrive.

Strategies for managing mixtures include (1) delaying the establishment of red alder for at least 3 to 6 years, (2) maintaining a low proportion of red alder in the stand (10 to 20 percent by stem count) and, (3) managing mixtures in small patches of single species, similar to most natural mixtures.

Growth and Yield
On good sites, height growth may exceed 6 ft/year for the first five years, and trees may attain heights of 60 to 80 ft in 20 years. Mean annual production rates in young stands have been estimated at 6.8 dry tons per acre. Growth slows substantially after the juvenile stage, particularly on poor sites. Site index ranges from 33 to 82 ft for base age 20 years and 60 to 120 ft for base age 50.

Yield tables based on site index and stand basal area (Chambers 1983) are available for estimating volumes of red alder in natural stands. Maximum volume per acre for red alder typically occurs at age 50 to 70, ranging from 5000 to 7000 ft3 per acre. On very good sites, annual volume growth rates may average 300 ft3 per acre for the first 10 years and 200 ft3 per acre over 30 years.

Relatively little information is available on growth and yield in managed stands of red alder. Major gains in average stem diameter and stand basal area appear to be possible with management of spacing in young stands. Optimistic projections anticipate sawlog rotations of 30 to 35 years for managed stands compared to 45 to 50 years for natural stands.

Interactions with Wildlife
For wildlife, red alder provides an important deciduous component in the predominantly coniferous forests of the Northwest. Typically, shrub and herb vegetation under red alder is quite different from that of conifer-dominated areas. A variety of animals seem to prefer or depend on red alder for food or habitat. Maintenance of a red alder component can provide greater habitat diversity within or between conifer stands.

Browsing, antler rubbing, and trampling by deer and elk can cause serious problems in young plantations. Red alder are very sensitive to this damage; effects on young trees include decreased growth, multiple stems, and poor stem form. Rapid growth and close spacings generally ensure that an adequate number of crop trees will escape serious damage. Risks of permanent damage are highest with plantations established at wide spacings (>12 ft). Areas of concentrated use by elk or deer should not be managed for red alder.

Both mountain beaver and fur beaver can cause substantial damage to seedlings. Planted seedlings may be the major food source for mountain beaver during the first years after burning or chemical site preparation. Preventative measures such as trapping should be considered if there is evidence of a significant mountain beaver population. Fur beaver can cause extensive mortality of saplings and trees up to 150 ft from streams.

Voles, mice, and other rodents often severely damage seedlings, particularly in grassy or marshy areas. Basal netting or tubing can protect seedlings from rodents.

Insects and Diseases
Young, undamaged red alder stands are fairly free of problems from insects and disease. Stem cankers are common in some young stands, although they seldom have significant impact except under stressful environments. Although red alder has long been perceived as highly susceptible to decay, some recent work shows that healthy, living trees are exceptionally resistant to decay after typical stem injuries.

Occasionally, serious outbreaks of defoliating insects can cause growth reductions in healthy stands and mortality in stressed stands. Tent caterpillars (Malacosoma disstria, M. californicum), red alder flea beetle (Altica ambiens), red alder woolly sawfly (Eriocampa ovata), striped red alder sawfly (Hemichroa crocea), and a leaf beetle (Pyrrhalta punctipennis) have all caused damage.

Genetics
Major gains in growth and quality may be possible with selective breeding of red alder. This is because red alder has a large amount of genetic variation, early sexual maturity, frequent seed production, rapid growth, and the capability of vegetative propagation. Little effort has been made to establish breeding programs.

Harvesting and Utilization

Cruising and Harvesting
Both cubic-foot and board-foot volume tables have been developed to estimate volume in standing trees from DBH and total height. Standard log grades, adapted from eastern hardwood log grades, have been developed for red alder. Most pricing decisions, however, are based on log diameter, length, and grade specifications developed by the specific log buyer.

Harvesting and transport costs for red alder are often higher than those for softwoods, although no special logging equipment is required. Red alder typically has lower volumes per acre and smaller, shorter trees. Red alder has a high green-weight-to-volume ratio, and natural stands produce a high percentage of logs with sweep and crook, which reduces the amount of logs that can be loaded on a truck. Most logging takes place in the dryer months; harvest volume declines in the rainy winter months because of road and site conditions.

Logs are generally scaled with Scribner log scale rules. Logs are also sold by weight or by the truckload. To prevent staining, red alder logs must be removed from the woods and processed within 6 to 8 weeks in the summer and 8 to 12 weeks in the winter.

Product Recovery
Sawlogs usually have a minimum small-end diameter of 6 in.; smaller logs are chipped for pulp. Lumber is graded under special National Hardwood Lumber Association (NHLA) rules for red alder; grades include Selects and Better, No. 1 Shop, No. 2 Shop, No. 3 Shop, and Frame. Unlike the standard NHLA grading rules, these grades are generally based on the best face of the piece, whereas the other NHLA rules are based on the poorer face. Grades can be applied to rough, surfaced, green, or dry lumber; in practice, lumber is usually dried and surfaced before grading. A considerable volume of the low-grade material is sawn into 1 X 4, 1 X 6, and 2 X 4 for making pallets.

Recent studies show that the cubic volume of red alder that is recoverable as lumber ranges from 30 percent in small diameter logs to 50 percent in larger logs. Grade recovery also varies by log size or log grade; e.g., 85 percent of the surface-dried lumber produced from 7-in. logs was pallet material, but 75 percent of the surface-dried lumber from 20-in. logs was No. 1 Shop and Select. An earlier study conducted with NHLA standard grades (rather than the modified red alder and maple grades) showed that the average green lumber grade recovery from alder logs was lower than that of other eastern and western hardwoods for a given log grade (Appendix 1, Table 2). For a given log diameter, grade recovery from butt logs is much higher than that for logs higher in the tree.

Most of the high-grade lumber is used for furniture, cabinets, and turned products. Lumber prices have remained high and are competitive with prices for eastern hardwoods. Red alder lumber is marketed internationally, with strong markets in the Pacific Rim countries and in Europe, especially Italy and Germany.

Red alder is peeled into veneer for both low-grade core stock and high-grade face material. Veneer logs are an increasingly important market that is competitive with sawlogs. Red alder is also widely used for pulp, both domestically and overseas, but staining and fiber deterioration are a problem in storing pulp chips for more than a few months. An evaluation of red alder as a raw material for structural panels, such as oriented strand board, found no problems in producing flakes, bonding with resins, or meeting structural design values.

Wood Properties

Characteristics
The wood of red alder is evenly textured with a subdued grain pattern, and is of moderate weight and hardness. Red alder is a light-colored or white wood when it is freshly sawn, but with exposure to air, the wood darkens and changes to a light brown hue with a reddish tint. There is no color distinction between heartwood and sapwood.

The growth rings are distinct, delineated by either a whitish or brownish line at the outer margin. The pores are uniformly distributed within a growth ring (diffuse porous). Rays are present and of two types, narrow (simple) and broad (aggregate). Both the pores and the rays are indistinct to the naked eye. The wood is without any characteristic taste or odor.

Weight
Red alder weighs about 46 lb/ft3 when green and 28 lb/ft3 when dried to 12 percent MC. The average specific gravity is 0.37 for green and 0.43 for ovendry.

Mechanical Properties
Because of its moderate specific gravity, red alder is not an exceptionally strong wood. In many applications this will be apparent as indentations on the surface of the wood. In furniture applications, it may be necessary to redesign joints and the sizes of structural parts to compensate for the often slightly lower strength values of red alder. Red alder holds nails well and does not readily split when nails are driven into it. Lower grades of red alder perform adequately as pallet material. See Appendix 1, Table 3 for average mechanical properties for small, clear specimens.

Drying and Shrinkage
Red alder lumber 5/4 and thinner is one of the easiest North American wood species to dry. Establishing and maintaining uniform color requires special handling and storage of logs and freshly cut lumber, and specially developed dry-kiln schedules. Variable coloration is due to the oxidation of extractives present in the wood. Colors may range from yellow to deep red and may be mottled.

Kiln-drying the lumber as soon as possible after sawing prevents mottling. Steaming the kiln charge at different temperatures for different lengths of time will result in different colored wood (from white to dark red); this technique allows the kiln operator to select the desired final color. See the table below for a standard kiln schedule. Other schedules are available for either lighter or darker final coloring of the wood.

Shrinkage values for green to ovendry wood based on original green sizes are low and average 4.4 percent in the radial direction and 7.3 percent tangentially. The green MC of the wood averaged 98 percent (ovendry basis).

Kiln Schedule

Machining
Red alder has an excellent reputation for machining. Due to the moderate specific gravity and the even texture of the wood, high throughput of material is possible. Quality surfaces can be obtained if sharp cutting edges are used. Some tear-out is possible during planing and shaping if tooling becomes dull or if feed rates are excessive. Red alder sands well without scratching and with a minimum of fuzzing. Its turning characteristics are similar to those of black cherry.

ChairAdhesives
The ease of gluing red alder is well known in the industry. It bonds well and there are no unusual problems when conditions are moderately well controlled.

Finishing
Because of its uniform, small pore structure and the consistency of color, red alder is a preferred wood for finishing. It accepts a variety of stain types and has been successfully substituted for other woods when properly colored stains are applied.

Durability
Red alder is a non-durable wood when subjected to conditions that are favorable to decay. We recommend that it be rapidly processed into lumber after harvest to prevent staining and decay. A reddish-purple stain develops in solid-piled lumber that has not been dried or treated with anti-stain chemicals. In-ground tests indicate that untreated, peeled round posts will decay and fail in 3 years on average, while split posts will last only 5 years.

Uses
Uses for red alder include face veneer, furniture, cabinets, paneling, edge-glued panels, core-stock and cross-bands in plywood, millwork, doors, pallets, woodenware and novelties, chips for waferboard, pulpwood, and firewood.

Related Literature

AGER, A.A., P.E. HEILMAN, and R.F. STETTLER. 1993. Genetic variation in red alder (Alnus rubra) in relation to native climate and geography. Canadian Journal of Forest Research 23:1930-1939.

AHRENS, G.R., A. DOBKOWSKI, and D.E. HIBBS. 1992. Red alder: guidelines for successful regeneration. Forest Research Laboratory, Oregon State University, Corvallis. Special Publication 24. 11 p.

ATTERBURY, T. 1978. Alder characteristics as they affect utilization. P. 71-81 in Utilization and Management of Alder. D.G. Briggs, D.S. DeBell, and W.A. Atkinson, compils. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station, Portland, Oregon. General Technical Report PNW-70.

BRIGGS, D.G., D.S. DeBELL, and W.A. ATKINSON, compilers. 1978. Utilization and management of alder. USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon. General Technical Report PNW 70. 379 p.

CHAMBERS, C.J. 1983. Empirical yield tables for predominantly alder stands in western Washington. Washington Department of Natural Resources, Olympia, Washington. DNR Report N. 31. 70 p.

CLEAVES, D.A. 1992. Marketing alder and other hardwoods. Oregon State University Extension Service, Corvallis, Oregon. Extension Circular 1377. 8 p.

CURTIS, R.O, D. BRUCE, and C. VanCOEVERING. 1968. Volume and taper tables for red alder. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station, Portland, Oregon. Research Paper PNW-56. 35 p.

DeBELL, D.E. Unpublished data. USDA Forest Service, Pacific Northwest Research Station, Olympia, Washington.

FEDDERN, E.T. 1978. Harvesting of red alder. P. 61-70 in Utilization and Management of Alder. D.G. Briggs, D.S. DeBell, and W.A. Atkinson, compils. USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon. General Technical Report PNW-70.

GEDNEY, D.R. 1990. Red alder harvesting opportunities in western Oregon. USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon. Resource Bulletin PNW-RB-173. 22 p.

HAEUSSLER, S., and J.C. TAPPEINER II. 1993. Effect of the light environment on seed germination of red alder (Alnus rubra). Canadian Journal of Forest Research 23:1487-1491.

HARRINGTON, C.A. 1986. A method of site quality evaluation for red alder. USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon. General Technical Report PNW-192. 22 p.

HARRINGTON, C.A. 1990. Red alder. P. 116-123 in Silvics of North America. Volume 2, Hardwoods. R.M. Burns and B.H. Honkala, coords. USDA Forest Service, Washington, D.C. Agriculture Handbook 654.

HARRINGTON, C.A., and R.O. CURTIS. 1985. Height growth and site index curves for red alder. USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon. Research Paper PNW-358. 12 p.

HIBBS, D.E., and A.A. AGER. 1989. Red alder: guidelines for seed collection, storage, and handling. Forest Research Laboratory, Oregon State University, Corvallis, Oregon. Special Publication 18. 6 p.

HIBBS, D.E., D.S. DeBELL, and R. TARRANT, editors. 1994. The Biology and Management of Red Alder. Oregon State University Press, Corvallis. 256 p.

HIBBS, D.E., W.H. EMMINGHAM, and M.C. BONDI. 1989. Thinning red alder: effects of method and spacing. Forest Science 35:16-35.

JOHNSON, H.M., E.J. HANZLIK, and W.H GIBBONS. 1926. Red alder of the Pacific Northwest: its utilization, with notes on growth and management. USDA, Washington, D.C. Department Bulletin 1437.

KOZLIK, C.J. 1987. Presteaming to minimize mottling in partially air-dried red alder lumber. Forest Research Laboratory, Oregon State University, Corvallis. Research Note 80. 6 p.

LENEY, L., A. JACKSON, and H.D. ERICKSON. 1978. Properties of red alder (Alnus rubra Bong.) and its comparison to other hardwoods. P. 25-33 in Utilization and Management of Alder. D.G. Briggs, D.S. DeBell, and W.A. Atkinson, compils. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station, Portland, Oregon. General Technical Report PNW-70.

LOWELL, E.C., and R.L. KRAHMER. 1993. Effects of lean in red alder trees on wood shrinkage and density. Wood and Fiber Science 25:2-7.

MACKIE, D.M, and G.J. Williams. 1984. Growth and utilization of alder within the Pacific coastal region. Pulp & Paper Canada 85(8):71-76.

PLANK, M.E., T.A. SNELGROVE, and S. WILLITS. 1990. Product values dispel “weed species” myth of red alder. Forest Products Journal 40(2):23-28.

PUETTMANN, K.J., D.E. DeBELL, and D.E. HIBBS. 1993. Density management guide for red alder. Forest Research Laboratory, Oregon State University, Corvallis. Research Contribution 2. 6 p.

RAETTIG, T., G.R. AHRENS, and K. CONNAUGHTON. Hardwood supply in the Pacific Northwest: a policy perspective. USDA Forest Service, Pacific Northwest Research Station, Portland. In preparation.

RESCH, H. 1980. Utilization of red alder in the Pacific Northwest. Forest Products Journal 30(4):21-26.

RESCH, H. 1988. Red alder: opportunities for better utilization of a resource. Forest Research Laboratory, Oregon State University, Corvallis. Special Publication 16. 13 p.

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WORTHINGTON, N.P, F.A. JOHNSON, G.R. STAEBLER, and W.J. LLOYD. 1960. Normal yield tables for red alder. USDA Forest Service, Pacific Northwest Forest and Range Experiment Station, Portland, Oregon. Research Paper 36.