Temperate rainforest’s distinct ecosystems altered by climate change

New research that focuses on the temperate rainforest stretching from California through B.C. to Alaska is helping scientists to understand how coastal environments will be influenced by our changing climate.

Research published this week in the journal Bioscience takes an interdisciplinary approach to evaluating land-sea interactions in the northeast Pacific coastal temperate rainforest (NPCTR). The paper evaluates the land-to-ocean flow of carbon and nutrients in the NPCTR, their influence on nearshore marine ecosystems, and how these connections are altered by climate change.

The paper is the first from a team of North American researchers looking at these issues throughout the entirety of the temperate rainforest – instead of being constrained by borders and administrative jurisdictions – and sets the foundation for future research.

“Ecosystems don’t recognize borders,” says SFU forest ecologist Ken Lertzman, professor emeritus, who is part of the research team, along with PhD student Ian Giesbrecht and scientists from university, federal and provincial research agencies in Canada and the United States.

“This is one of the first papers looking at how climate change affects the NPCTR as a whole and asking the big questions about how processes connecting and driving ecosystems will be changed. It’s a pretty big deal in our field and it’s really just the beginning.”

Coastal marine environments in this region are dynamically linked with the land through rivers and streams. This tight coupling of terrestrial, freshwater, and marine ecosystems is a distinct element of the North Pacific Coastal Rainforest. The coastal margins are a unique study area for scientists working to understand how coastal environments will be influenced by our changing climate. 

The NPCTR is a global hotspot for terrestrial carbon storage and its transport into coastal waters. But these processes will be altered by everything from increasing forest fires, to shifting seasonality of rain and snowfall, to changing marine productivity, notes Lertzman, who, with Giesbrecht, contributed analyses of the Coastal Temperate Rainforest region and of the diverse watersheds across it.

Studies conducted in the region typically focus on distinct ecosystems rather than considering the tight linkages between the terrestrial and marine ecosystems.

In their paper, the authors highlight the distinct characteristics of each of the major ecosystem components of the coastal margin, from the forests, through the rivers, to the ocean. Their collaborative work will help to shed light on how these components, and the interactions among them, will be altered by climate change.

“Although coastal temperate rainforests make up a relatively small portion of the land cover on the planet, they sequester more carbon per unit area than any other forested ecosystem. It’s important to understand the processes at play that sequester and move carbon out of these ecosystems because of their disproportionate impact on global carbon cycling,” said Alison Bidlack, director of the Alaska Coastal Rainforest Centre at the University of Alaska Southeast and lead author on the study.

The paper is the product of a workshop organized by the Coastal Rainforest Margins Research Network, supported by the National Science Foundation, the University of Washington Freshwater Initiative, the Hakai Institute, and the University of Alaska Southeast. Giesbrecht is a Hakai Institute scientist and a member of the Steering Committee for the Research Network.