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Geos Institute helps communities build resilience in the face of climate change

Old-growth Forests Hold Keys to Adapting to Climate Change

Scientists released new findings on the importance of mature and old-growth forests in preparing the Klamath-Siskiyou region of southwest Oregon and northern California for global climate disruptions. Published in the January edition of The Natural Areas Journal (Volume 32: 65-74) by the Natural Areas Association, the study calls on regional land managers to protect mature and old-growth forests as an insurance policy for fish and wildlife facing mounting climate change pressures from rising temperatures, declining snow levels, and reductions in fog along the coast.

The project was led by the Ashland-based Geos Institute who brought together scientists with backgrounds in climate change science, Klamath-Siskiyou regional ecology, and conservation planning to comb through data on temperature and precipitation changes and to develop recommendations to help adapt ecosystems while the ecological and economic costs are relatively low.

According to Dominick DellaSala, Chief Scientist & President of Geos Institute, who led the project team, “for millennia our region’s mature and old-growth forests have been a wellspring for nature and they now hold the keys to sustaining the very ecosystem benefits we will increasingly depend on for freshwater, clean air, and viable fish and wildlife populations as global climate disruptions increasingly impact our area.”

One of the authors of the study, Reed Noss, Professor of Conservation Biology at the University of Central Florida, underscored the importance of the studies findings for land managers. “Climate change, combined with habitat loss and fragmentation, is the greatest threat we face to nature. This study shows that land managers can reduce impacts of climate change by protecting older forests in a region whose biological diversity has been recognized globally as among the top ten coniferous forests on earth.”

The study used computer mapping and extensive datasets on regional climate and wildlife distributions to determine what areas are most likely to hang on to their local climatic conditions for wildlife seeking refuge from rising temperatures and changes to precipitation caused by climate change disruption. Oldgrowth and mature forests, with their closed canopies and moist environments, are predicted to remaincooler for longer periods of time, therefore providing refuge for species that depend on these conditions.

Key Findings:

  • Based on related studies undertaken by Geos Institute and partners, climate disruptions in the Rogue basin, for instance, will likely include: (1) an increase in average annual temperatures from 1 to 3° F by around 2040 and 4 to 8° F by around 2080; (2) substantial increases in summer temperatures of 7 to 15° F by 2080; and (3) snow turning more often to rain in lower elevations with a decrease in average January snowpack and corresponding decline in spring runoff and stream flows. Other studies document significant reductions in fog along the coast, which pose risks to coastal redwoods.
  • While all of the regions’ older forests are important, those on north-facing slopes and in canyon bottoms, lower- and middle-elevations, and wetter coastal mountains will provide for cooler, moister conditions as the rest of the region heats up.
  • Several areas deserve immediate conservation attention because they contain high concentrations of older forests with preferred climatic conditions, including along the southern bend of the Klamath River Northern in California; lower slopes of the Klamath River from around China Point eastwards to Hamburg in California; northern slope of the Scott Bar Mountains and along the lower Scott River in California; coastal areas in Oregon and in the foothills behind the redwood belt in northwestern California; the Middle Smith River in California; areas west of the Kalmiopsis Wilderness, southwest Oregon; southeastern watersheds of the Siskiyou Mountains (e.g., Dillon and Rock Creek area, California); and the northern Siskiyou Mountains to western Siskiyou Crest region, California. These areas are likely to serve as wellsprings of nature as the climate increasingly shifts.
  • BLM landholdings in western Oregon are noteworthy as they contain over 1.6 million acres of mature and old-growth forests, which are critical for threatened species like the spotted owl and marbled murrelet, and 1.8 million acres of habitat critical to coho salmon recovery. These are some of the last low-elevation forests in the region that can still function as a climate refuge but are at the biggest risk from logging proposals being championed by Congress.
  • Reducing non-climate stressors from logging, roads, and other land uses is the single most important adaptation measure that land managers can take now to reduce climate related impacts.

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