Research & Writing by Madison Magalski
Cascadia, a bioregion spanning 2,500 miles along the Pacific coast from northern California to south-central Alaska, is home to the largest temperate rainforest in the world. Thousands of islands dapple Cascadia’s rugged northern coast, a land where spirit bears, wolves, ancient trees, salmon, and human have flourished mutually in an inextricably entwined web for millennia. In southern Cascadia, the tallest trees on the planet stand in blankets of fog, harboring entire ecosystems in their canopies. Cascadia is a land defined by connectivity: of sea and forest, of human and animal, of watershed and myth.
A coastal climate of mild temperatures and high annual precipitation define these conifer-dominated forests. Tree species, such as coast redwood (Sequoia sempervirens), western red-cedar (Thuja plicata), Sitka spruce (Picea sitchensis), western hemlock (Tsuga heterophylla), and Douglas-fir (Pseudotsuga menziesii), are long-lived, fast growing, and capable of accumulating large amounts of biomass. Temperate rainforests accumulate biomass at one of the highest levels on the planet, higher than both the tropics and the boreal. The diverse landscape mosaic of Cascadia encompasses much more than large conifers: an estimated 350 bird and mammal species, 48 reptiles, hundreds of fungal, lichen, and bryophyte species, as well as thousands of invertebrates and soil organisms call Cascadia home. Five species of Pacific salmon also rely on the rainforests of Cascadia, as they return to spawn in the forested streams of their birth after a life at sea, bringing within their bodies a bounty of marine nutrients anticipated by bear and human alike.
The richness and diversity of Pacific temperate rainforests are no exception when it comes to the widespread unraveling of the tapestry of life on this planet. Pervasive land use change and industrial logging wrought the forests of Cascadia throughout the 19th and 20th centuries. The First Peoples of the region, such as the Tlinglit, Haida, Salish, Umpqua, Pomo, and Yurok, whose cultures are deeply rooted in the ecosystems they reside, were denied rights to their ancestral lands and cultural practices. This drastic transition from subsistence economies to natural resource extraction, that accompanied European colonization, has left long-lasting devastation in both the human and ecological communities of Cascadia. Close to 90% of native forests of the region have been lost. Intact temperate forests cover less than 5% of their historic range in California, Oregon and Washington; designating temperate old-growth in the contiguous US as an endangered habitat, or a habitat with 85-99% cumulative destruction. Although roughly 68% of the temperate rainforest in British Columbia and 90% in Alaska are still considered to be intact, only a fraction of that percentage is protected, leaving the majority to be intensively managed for timber production. Numbers of "intact forest” can also be misleading, as even-aged managed stands provide much fewer ecosystem services, typically harbor much less biodiversity, and sequester less carbon than old-growth stands.
In the face of climate change and an estimated loss of 150–200 species from the planet each day, according to UN Environment Programme, the historic precedence of exploitation and degradation of Cascadian forests no longer has a place. From an economic perspective, the timber industry has been in decline in the Pacific Northwest for decades. Due to mechanization, market fluctuations, and controversial policy changes, rural communities that were once economically sustained by timber production continue to face significant job losses. Boom and bust cycles define the pathology of resource-based industries, ultimately leaving communities with economic loss and degraded landscapes. In order to foster resilience, both social and ecological, there must be a shift away from this extractive paradigm towards one prioritizing the conservation of intact ecosystems and the restoration of degraded ones.
The temperate rainforests of Cascadia have much to offer if their biodiversity, carbon sequestration, and climate mitigation potential is appreciated. Due to their ability to accumulate large amounts of biomass, temperate rainforests are considered to be significant global carbon sinks. In contrast, the conversion of old-growth forests to managed plantations results in large amounts of carbon released into the atmosphere. As land use change accounts for 24% of GHG emissions worldwide, the preservation of temperate rainforests is felt globally. These forests further help to mitigate regional temperature change through their interactions and feedbacks with the hydrological cycle.
In considering the potential future of temperate rainforests, it is paramount to emphasize the complexity of natural systems. Cascadia is particularly complex as an interface of forest, sea, and freshwater: with boundaries porous and interactions innumerable. The health of the soil, watersheds, forests, air, fungi, animals, and humans all depend on one another. Planning for resilience of temperate rainforests in a changing climate will require embracing whole communities.
A wealth of studies suggest that greater diversity allows for greater adaptive capability and resilience against stress and disturbance. In order to sustain the wealth and beauty of Cascadia for future generations, we must work towards fostering as much diversity as possible throughout the entire region. Permanent conservation of the unique biodiversity sustained in the remaining old-growth and restoration efforts encompassing as many native species as possible will help harness the potential of Cascadian forests in our world’s uncertain future.