Can Thinning in Previously-Logged Forests Encourage Old-Growth Forest Characteristics While Buffering Impacts of Climate Change?

Close-up of mossy log at Dungeness National Wildlife Refuge, WA

    NW CASC Fellow

  • Kavya Pradhan, University of Washington,
  • Faculty Advisor

  • Janneke Ris Lambers, University of Washington,
  • Willapa National Wildlife Refuge
  • The Nature Conservancy
In Progress

Forest restoration efforts in the iconic temperate rainforests in the Pacific Northwest have focused on speeding up succession, or the natural pattern of forests changing over time, to promote the development of old-growth forest characteristics in secondary forests. One such method involves managing tree stand density by restoration thinning to ensure the development of older and structurally diverse habitats that support biodiversity. However, forest managers need to consider both habitat structure and climate change. This means understanding how restoration practices focused on stand-thinning interact with a promising approach to increase resilience to climate change – preserving landscape features that help retain moisture and stabilize temperatures in forests, helping to buffer biodiversity from the impacts of climate change. These features, referred to as climate change microrefugia, may offer a potential refuge for biodiversity and species of concern as climate change accelerates.

Although both thinning and maintaining microrefugia have been recognized as important forest management techniques, there is little research about how these management approaches interact. The goal of this project is to locate current climate change microrefugia, examine the impacts of these microrefugia in restoring old-growth characteristics and assess whether restoration thinning has positive or negative effects on climate change microrefugia. Using pre- and post-thinning surveys, Kavya seeks to gain clarity regarding whether managing for old-growth restoration and climate change microrefugia can be implemented together, or if there is a trade-off. The findings from this study will support climate-smart forest management for project collaborators at the Willapa National Wildlife Refuge and The Nature Conservancy.