The temperate rainforest of Pacific Rim is an obvious indicator of the environmental forces at work in the park. Wherever you look in the park, whatever the season, the dominating colour is green. Rich and lush, the forests of the park are divided into 6 communities contained within the Coastal Western Hemlock Biogeoclimatic Zone, representing one facet of the Northern Pacific Coast Forest. This old-growth forest is known as one of the highest biomass-producing areas in the world.
Along the coastal edge, brushed by sea-spray, giant Sitka spruce dominate the Spruce Fringe forest community. An understory of salal, black twinberry and shrubby Pacific crabapple fill in the inner forest. The most exposed shoulder of the Spruce Fringe is stunted by wind and spray, forming a distinctive, wind-sheared krummholz that buffers the inner forest from the full force of Pacific weather systems. Overseeing this deformed margin, lofty Sitka spruce standing 50 to 90 metres tall survey the sea.
The Cedar-Hemlock forest community is found further inland, where the ranks of salt-tolerant Sitka spruce thin, becoming outnumbered by western hemlock and western red cedar. Accompanying these conifers, there is an understory of red huckleberry, salmonberry, blueberry and salal. Distinctive and unique within this forest are "candelabra-like" red cedar. Stressed by strong winds, heavy rainfall, low nutrient conditions and a high water table, western red cedar struggles with the elements, developing twisted trunks and multiple, gray-weathered crowns. Many of these trees are hundreds of years old, justly earning their silvered and wizened appearance.
Where soil depths and fertility are optimal, western red cedar and western hemlock are joined by amabilis fir to form the Climax Rainforest community. This old-growth forest supports a diversity of animals, many of which appear to be dependent upon its unique forest structure. Western yew, a small "cranky-looking" conifer, is scattered throughout this forest, along with salal, false azalea, blueberry and epiphytic (one plant growing upon another) mosses and ferns. The Climax Red forest is characterized by an irregular, multi layered canopy, giant conifers, standing snags, and fallen nurse logs with rooted seedlings.
The Wooded Bog community develops in areas with poor drainage. Stunted shorepine, a coastal relative of the erect interior lodgepole pine, grow among sphagnum moss, Labrador tea, and bog laurel. This community of plants is specially adapted to the wet acidic conditions of the bog. Skirting this wet zone evergreen huckleberry fills the transitional margin into other forest zones.
The Stream Banks and Roadside forest communities are most distinctly represented by red alder. On flood swept stream beds, cleared roadsides and logged areas, groves of alder become ingrown with shrubby willows, cascara, salmonberry and thimbleberry. The opportunistic scotch broom, introduced to Vancouver Island in 1849, has firmly established itself along roadways throughout the region. It's vivid yellow splash of springtime bloom delights highway users, but is thought of in less endearing terms from a resource management perspective. This hardy "alien" displaces native species.
There are some sections of disturbed forest within the park. These are areas of past human settlement or forests that have been commercially harvested before the land was set aside as a national park reserve. Douglas fir, amabalis fir and Sitka spruce were planted after harvesting, with western hemlock and red cedar regenerating on their own. The light-loving and fire-dependent Douglas fir artificially introduced to these areas will ultimately be surpassed by the more shade-tolerant indigenous species. Eventually, the indigenous forest cover will prevail, never to be cut again.
Forest fires in the area of the park are rare due to the mild, wet climate. Abundant moisture retained within the soil and the debris covering the forest floor keep the fire hazard to a minimum. Windthrow openings in the forest canopy and the natural processes of insect and disease act as the usual agents of forest rejuvenation in the absence of fire. The result is a forest structure of uneven age, providing diverse and varied habitat for wildlife in the park.