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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.

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 guide Save the Redwoods League in deciding where to protect and restore redwood forests facing climate change impacts.

Each year, the RCCI studies the health of redwoods across the landscape. Researchers measure tree structure and growth rates, as well as biodiversity and forest carbon storage, in a monitoring network spanning 18 sites in the coast redwood and giant sequoia ecosystems. In 2019 and 2020, researchers will study redwood growth rates in 20 new forests. These studies will yield a better understanding of how climate change is uniquely affecting old and young, coastal and inland, and low- and high-elevation redwood forests across California.


Results

  • Second-growth redwood forests can accumulate about a third as much aboveground biomass as comparable old-growth forests in less than 200 years. Redwoods gain height rapidly in second-growth forests, but biomass accumulation (and therefore, significant carbon storage) in the tallest second-growth forests is much lower than in the tallest old-growth forests. Learn more.
  • Ancient redwood forests store at least three times more carbon above ground than any other forests on Earth.
  • Changing environmental conditions have triggered a growth increase in coast redwoods and giant sequoias.
  • California summers have warmed, but precipitation has remained highly variable and not decreased over recent decades.

One discovery by our leading scientists is that ancient redwood forests store at least three times more carbon above ground than any other type of forest. “The trees are sequestering carbon in their wood, which is incredibly resistant to rot,” said Emily Burns, the League’s former Director of Science.

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

Another finding is that because of environmental changes, some redwoods have grown more since the 1970s than they ever have. One hypothesis for the growth is that rising temperatures are lengthening the growing season. In the coast range, decreasing fog may provide the trees more access to sunlight. Another factor may be more carbon dioxide in the air. You can learn more by watching Stephen Sillett present his findings at the 2013 Redwood Ecology and Climate Symposium.

“These results bolster our mission to protect redwoods because these trees are pulling incomparable amounts of carbon dioxide out of the atmosphere, which helps combat global warming,” Burns said.

Review RCCI Research Abstracts to learn more about these initial results.

The RCCI revealed that ancient redwood forests are doing well in the face of a changing climate, and indeed, through their remarkable capacity to capture carbon, they are playing a positive role in the effort to fight climate change.

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. Thank you.


Climate Monitoring

Monitoring the local weather and long-term climate is an integral part of the Redwoods and Climate Change Initiative (RCCI). Beginning in 2011, scientists from UC Berkeley installed weather stations across the range of coast redwood and giant sequoia forests in six of the 13 RCCI study sites. Monitoring environmental conditions over time at these study sites will enable scientists to understand (1) what weather events are impacting the trees at each site, (2) how climate is changing in these iconic forests, and (3) may help identify sites that are changing most dramatically.

At each site, a weather station was installed at the top of a sentinel (emergent) tree and on the forest floor. The purpose of having a treetop and a ground-level station is to be able characterize the conditions that both fully-grown trees are experiencing and the next generation of giants (seedlings and saplings) as well as other plants and animals who inhabit the forest floor are experiencing.

The weather data collected so far indicates that in the coast redwood forests, temperatures and precipitation follow a predicable latitudinal gradient, with the forests in the north being on average cooler and receiving more rain than those in the south. The temperatures at the giant sequoia sites are strongly influenced by the elevation of the site, more than the latitude. Giant Forest is at the highest elevation and is on average the coldest site while the most northern site, South Calaveras Grove, is at the lowest elevation and is the warmest. Precipitation in the giant sequoia forests generally follows a latitudinal gradient as seen in the coast redwood region.

Although the average, year-round conditions follow those general latitudinal and elevational gradients, the season to season (interannual) dynamics are a bit more complicated. For instance, at Montgomery Woods State Natural Reserve in north-central California, the average summer temperature is much higher than at the most southern site at the Landels-Hill Big Creek Reserve. This is because Montgomery Woods is farther from the coast, nested within an easterly facing steep valley, and is not cooled by summer coastal fog.

2014 Weather Report

The RCCI weather station records show that coast redwood and giant sequoia forests had less rainfall and warmer temperatures in 2014 relative to previous years. With less water coming into the forest and warmer days drying the soil, these drought conditions can greatly reduce water resources for the trees and other plants. To find out if the current drought is affecting the forest, the RCCI researchers are visiting all the study sites to check for tree mortality and study redwood growth rates.

Since 2011, forest air temperature has warmed. This graph shows the average monthly temperature at the redwood treetop in coast redwood and giant sequoia forests. The top graph is from the giant sequoia forests at Calaveras Big Trees (CBT), Giant Forest (GF) and Freeman Creek (FC). The bottom graph is from coast redwood forests at Jedediah Smith Redwoods State Park (JSU), Montgomergy Woods State Natural Reserve (MW) and Landels-Hill Big Creek Reserve (BC).
Since 2011, forest air temperature has warmed. This graph shows the average monthly temperature at the redwood treetop in coast redwood and giant sequoia forests. The top graph is from the giant sequoia forests at Calaveras Big Trees (CBT), Giant Forest (GF) and Freeman Creek (FC). The bottom graph is from coast redwood forests at Jedediah Smith Redwoods State Park (JSU), Montgomery Woods State Natural Reserve (MW) and Landels-Hill Big Creek Reserve (BC).

Watch our latest video to learn more about how RCCI scientists monitor weather in the plots. You can also check out a fun video about the challenges of maintaining weather stations in bear country.


Research Plot Photo Tours

Jedediah Smith Redwoods State Park: Upslope Plot

Jedediah Smith Redwoods State Park: Lowland Plot


Redwood National Park: Upslope Plot

Redwood National Park: Alluvial Plot


Humboldt Redwoods State Park Plot


Big Basin Redwoods State Park Plot


Calaveras Big Trees State Park: South Grove Plot

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