RCCI Forest Network

We are learning how climate change is impacting redwood forests by tracking forest conditions over time in the RCCI network of forest plots distributed throughout the geographic range of coast redwoods and giant sequoia.

Redwood and Climate Change (RCCI) map of research plots.
Click to view larger image.

Save the Redwoods League and Humboldt State University lead the Redwoods and Climate Change Initiative (RCCI), a collaborative research program launched in 2009 to study past, present, and future impacts of climate change on coast redwood and giant sequoia forests.

The results can guide Save the Redwoods League and other forest stewards conserving redwood forests.

Beginning in 2009, researchers installed 16 long-term forest monitoring plots in old-growth coast redwood and giant sequoia forests to better understand how forests change through time. Each tree was measured and mapped in these 1-hectare (~2.47 acres) sized plots, and they have all been visited annually to document mortality and new trees. Every five years, the plots are fully re-measured. Over time, this helps us better understand the demographics of the forest, and can be a place to watch for early warnings signs of threats and stressors to the forest. It is also important for understanding biodiversity and carbon storage.

At each of these sites, researchers climbed and mapped five individual old-growth trees to better understand tree structure and growth rates, as well as forest carbon storage.

Over time, we realized that although the old-growth forests are critically important, we need to develop a better understanding of the younger, recovering forests that make up 95% of the coast redwood range. We also needed to understand how climate change might be differentially affecting forests on the edge of the range – far inland or to the south. So in 2018 we added two additional 1-hectare, long-term monitoring plots, and identified sites to climb trees in at least 20 new forests, spread throughout old and young, coastal and inland, and northern and southern redwood forests across California.

Results to date

  • Ancient coast redwood forests store more carbon above ground than any other forests on Earth, with giant sequoia coming in as a close second.
  • Scientists observed significant growth increase in the latter half of the 20th century in many old-growth coast redwoods and giant sequoias, even during the 2012-2016 drought.
  • Second-growth coast redwood forests can accumulate about a third as much aboveground biomass as comparable old-growth forests in roughly 150 years.

Growth rates

One surprising finding is that some old-growth redwoods have grown more since the 1970s than they ever have, even during the 2012-2016 drought. One hypothesis for these growth rates is that rising temperatures are lengthening the growing season. Another factor may be more carbon dioxide in the air. In the coast range, decreasing fog may provide the trees more access to sunlight.

However, some forests at the extreme edges of the coast redwood range did show reduced growth rates during drought, which may be due to increased competition for resources, since regenerating forests are often denser. Second-growth forests did not see the same growth surge that old-growth forests did in the latter half of the 20th century, perhaps for the same reason, though more research is needed to better understand these forest dynamics.

Exceptional carbon storage capacity

One of the critical discoveries by our leading scientists is that ancient redwood forests store more carbon above ground than any other type of forest.

“As trees grow, they pull carbon out of the atmosphere and store it in their trunks and branches. Redwoods are uniquely suited to this task, storing more carbon per acre than any other forest type. Their wood is also highly rot resistant, which means this carbon will stay locked up for a very long time,” said Kristen Shive, the League’s Director of Science. “This is just another way in which these trees add value to our world.”

Your generous support helped to make this research possible and funds are still needed to continue this critical work. The more we know about the redwoods, the better we can look after them. We look forward to learning and sharing much more through the important work of the RCCI program.


Scientists of the Redwoods and Climate Change Initiative study the coast redwood canopy in Redwood National and State Parks. Photo by Stephen C. Sillett

Research from Save the Redwoods League and Humboldt State University Confirms Significant Role of Redwood Forests in California’s Climate Fight

Recent findings bolster more than 10 years of research, confirming massive carbon storage in old-growth redwood forests and potential of younger, previously logged forests.

Research Plot Photo Tours

Jedediah Smith Redwoods State Park

Upslope Plot

Lowland Plot

Redwood National Park

Upslope Plot

Alluvial Plot

Humboldt Redwoods State Park Plot

Big Basin Redwoods State Park Plot

Calaveras Big Trees State Park

South Grove Plot