Stretching across the vast landscape of the Northern Pacific coast is the largest remaining temperate rainforest in the world: the Pacific Coastal Temperate Rainforest (PCTR). The PCTR ecoregion encompasses everything from barren rock peaks, glacial icefields, alpine tundra, wetlands, spruce, hemlock, and cedar forests, to the estuaries and fjords along the coastal margin.
Three times the amount of water that flows from the Mississippi River into the Gulf of Mexico annually courses through the rivers and streams of the Northern PCTR each year.
Aided by steep terrain, high precipitation, and glacial runoff, this immense freshwater flow carries nutrients, sediment, and substantial amounts of organic carbon that affect ocean chemistry and support coastal food webs. The fresh water influence extends far beyond nearshore waters– the influx of coastal runoff bolsters ocean productivity, adds to the dynamics driving the Alaska Coastal Current, and spreads pockets of low-salinity, nutrient-rich water far into the Gulf of Alaska.
In turn, the ecosystem supports the salmon that run its rivers, endemic plants and animals, and communities with deep ecologic, economic, and cultural ties to the land. In southeast Alaska, Washington, Oregon, and British Columbia, billions of dollars a year stem from fisheries, timber, and tourism industries that are intimately connected to the health of the ecoregion.
Globally, coastal margins are home to nearly 2.4 billion people and are seeing pronounced effects of climate change. The PCTR in particular is highly sensitive to changes in climate. Already, the region is experiencing among the highest rates of glacial mass loss on the planet, and shifts in forest type and increased forest fire activity in some regions are occurring. Changes in snowpack, storm patterns and severity, and seasonal drought are just a few of the impacts the PCTR is likely to face. These real and predicted changes underscore the need for a better understanding of the ecosystem functions of the coastal temperate rainforest.
The Coastal Rainforest Margins Research Network is working to measure the complex interactions between the soils, streams, forests, and the ocean to determine how water, carbon, and other materials move through coastal watersheds to marine environments. Some of the goals of the research network include determining how climate change will affect the land-to-ocean flow of materials, what role the PCTR has in global carbon sequestration now and in the future, how important terrestrial nutrients are to marine ecosystem processes, and what might happen if these processes change.
Answering these questions will help prepare local communities and industries for a warming and increasingly variable climate. Climate-driven changes in the movement of freshwater, carbon, and nutrients from coastal watersheds may impact downstream ecosystems and economies in both predictable and unanticipated ways. This research will inform decisions about ecosystem management, infrastructure, and policy to build resilience in coastal communities. It will also provide insight to coastal temperate rainforests worldwide, and inform research into climate-driven changes in other coastal margin areas.