Viewed from the Inside Passage, southeastern Alaska forests appear relatively homogeneous. However, more careful examination reveals a pattern of streams, muskegs, small ponds, areas of tree blowdown, clearcutting, alpine and coastal meadows, and barren rock outcrops. The most homogeneous stands of healthy trees, which make up a large part of the commercial timber, occur near tidewater. Tree heights and quality diminish progressively upslope. The principal tree species in the region are western hemlock—57 percent by volume in mature forests—and Sitka spruce—37 percent. Western red cedar, found only south of Frederick Sound, and Alaska cedar, which occurs throughout the area, together total four percent of the total forest volume (Harris and Farr 1974).

Mature Sitka spruce trees are tall and straight with diameters of more than 10 feet (3 m) and heights of more than 200 feet (61 m). They may live 800 years, and the largest known individual in Alaska had a trunk diameter of 14.5 feet (4.5 m). Sitka spruce have little taper, but commonly develop enlarged buttressed bases and open conical crowns. The species develops best on well-drained alluvial soils. Drainage is apparently the critical growth factor.

The wood has a fine, uniform texture of generally straight grain with a few resin ducts. It is of medium weight, stiffness, hardness, resistance to shock, shrinkage, bending and compressive strength, and has a high strength/weight ratio. The wood is easily worked and kiln dried and is moderately resistant to decay. Its most desirable commercial characteristics are its long, strong fibers and the ease with which it can be pulped. The fibers bleach well, making it suitable for a variety of papers, fiberboards, rayon, and plastics. Other products include siding, food containers, casks, venetian blinds, boat masts, spars and oars, cabinets, scaffold planking, and aircraft. However, its major uses are presently for dimension and cant lumber and pulpwood, particularly in Alaska where more than 88 percent of the commercial Sitka spruce in the United States grows.

The tall, slender western hemlock may reach a height of 190 feet (58 m) and a diameter of more than five feet (1.5 m). The crown is comparatively short and narrow with drooping branches, and it may have a fluted base. Western hemlock trees attain their greatest size on moist flats and lower slopes between sea level and 2,000 feet (600 m) elevation. These trees flourish on deep, well-drained soils, but they will also grow well in shallow soils if there is sufficient moisture. They are tolerant of shade.

The wood is fairly light, has medium bending and compressive strength, workability, hardness, and shock resistance. It shrinks considerably when dried and has low resistance to decay. The wood is nonresinous and has long dense fibers, making it one of the best pulpwoods. It is also used for dimension lumber, cabinets, plywood, poles, and marine pilings.

Western red cedar may attain heights up to 130 feet (40 m) and diameters of six feet (1.8 m). They have pointed conical crowns and horizontal branches that curve up at the tips. The boles of mature individuals are limby and have considerable taper, often with a swollen or buttressed base. Little is known about the soil preferences of this species. Growth is slow, but when competition is removed, the species responds well to additional light and space. It is not found north of Petersburg and Frederick Sound.

The wood has a fine, moderately even texture, is lightweight, moderately limber and soft, shrinks little when dried, but has little bending, compressive strength, or shock resistance. It is fairly easy to kiln dry and work, takes paints and stains satisfactorily, and is very resistant to decay.

Because the wood retains its size and shape exceptionally well, it is favored in boat construction. It is also widely used for roofing shingles, telephone poles, fence posts, clothes closets, and chests.

Mature Alaska cedar trees are often as tall as 100 feet (30 m) and as much as three feet (0.9 m) in diameter. They are considerably larger in coastal forests to the south. Alaska cedar is one of the slowest-growing, long-lived trees in North America. Healthy individuals 200 to 1,200 years old are fairly common, and some have been known to live as long as 4,000 years. Trunks may be fluted and swollen at the base and taper sharply where growth is especially slow. Many trees lean slightly. The crown is narrow and conical and the hanging branchlets give the tree a weeping appearance. Some trees appear ragged because of widely separated branches.

In Alaska, the highest quality cedars occur on thin organic soils over bedrock with abundant groundwater seepage. The tree is seldom found on deeper, better-drained soils of the lower slopes and valley bottoms, possibly because of competition from hemlock and spruce. The species also occurs on heavy, wet, organic subalpine soils, muskeg, and half-bog soils.

The fine-textured, straight-grained quality of the wood makes it easy to work. It is moderately heavy, strong, stiff, hard, and shock resistant and has a high oil content which makes the wood strongly aromatic. The heartwood is very durable and resists marine woodboring insects and decay fungi. Because of this durability, smooth-wearing quality, and workability, the wood has a wide variety of uses, especially in boat building.