Plants

Unofficial trails including this one in Redwood National and State Parks' Grove of Titans result in trampling that can harm roots of ancient trees. Photo by Claudia Voigt

Mitigating Effects of Unofficial Trails on Ancient Redwood Groves

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And now, because of internet and mobile technology, the locations of more and more of the tallest redwoods are becoming public knowledge, drawing more people to these giants. This often leads to people blazing their own trails either because the officially designated trail does not provide close access, or because there is no official trail to a specific tree or grove. These unofficial trails are called social trails. So, just how great is the impact of these unofficial trails? Learn more about this research.

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The study found that although trees within 5 meters of each other (like these here) were more likely to be clones than trees farther away, they weren’t always. Photo by Jason Hollinger, Flickr Creative Commons

Some Coast Redwoods May Seem to Be Clones, but They’re Not

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If you’ve visited a coast redwood forest, you’ve probably seen these trees growing around the stump of a logged giant. These “fairy rings,” as they’re known informally, show how the coast redwood reproduces asexually by sending new sprouts up from the trunk base of a parent redwood. The mystery was whether these sprouts are genetically identical copies of the parent redwood. Because 95 percent of the current coast redwood range is younger forests, understanding the genetics of the coast redwood is critical for conservation and restoration. Learn more about this research.

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A study confirms that northern giant sequoia groves have lower genetic diversity than central and southern groves. Photo by Bob Wick

Lower Genetic Diversity Puts Giants at Risk

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Recent League-funded research by Richard Dodd, an Environmental Science Professor at the University of California, Berkeley, confirms that northern groves (north of the Kings River drainage) have lower genetic diversity than central and southern groves. This could have profound consequences for long-term conservation strategies for the species, especially considering the changing global climate. Learn more about this research.

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Good giant sequoia regeneration was strongly associated with canopy gaps. Photo by Marc D. Meyer

Promoting Giant Sequoia Regeneration

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Giant sequoias can live for thousands of years, but they sometimes have difficulty getting started. Unlike coast redwoods, giant sequoias rarely sprout from their bases. Their reproductive future lies in their tiny (0.2-inch-long) seeds, which need just the right combination of soil, sun and moisture to survive. Learn more about this research.

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A researcher assesses the health of giant sequoias planted more than 30 years ago in an area hotter and drier than their original homes. Photo by John-Pascal Berrill

Small Giant Sequoia Groves May Not Endure

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More than 30 years ago, giant sequoia seeds were collected in 23 groves representing the species’ range from north to south in the Sierra Nevada. They were propagated and planted on US Forest Service land 20 miles east of Auburn, California, that was hotter, drier, lower in elevation and farther north than any of their original homes. This experiment, the legacy of William J. Libby, UC Berkeley emeritus professor and Save the Redwoods League board member, has been studied and carefully maintained ever since. Learn more about this research.

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Researcher Emily Burns noticed that half the ferns in coast redwood forests were evergreen and half were deciduous. Deciduous ferns turn white in the fall while the evergreen ferns stay vibrant green.

Deciduous Ferns May Hold Advantage as Climate Changes

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In 2010, funded by Save the Redwoods League and the National Science Foundation, Professor Jarmila Pittermann and Burns began a study comparing the leaves of evergreen and deciduous ferns. Interested in their response to drought, they chose midsummer, just before the deciduous ferns would shed their leaves, in the drier southern part of coast redwoods’ range (in the Santa Cruz Mountains and Big Sur). They expected that evergreen leaves, which are thicker, would show fewer signs of water stress. Learn more about this research.

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One year after a wildfire, burnt redwoods regrow foliage. Photo by Benjamin S. Ramage

Redwoods Regrow After Fires

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In the past 70 to 80 years, most fires in California’s coast redwood forests were prevented or suppressed. But in 2008, more than 2,000 fires ignited forests in Northern and Central California during a single summertime lightning storm. Overwhelmed by conflagrations in drier areas, firefighters allowed many of fires in coast redwood forests to burn. Learn more about this research.

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Sudden oak death killed a tanoak stand creating an opening in this forest. Tanoak plays an important ecological role in the redwood forest. Photo by Benjamin Ramage

Tanoak Decline in Redwood Forests

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Tanoak (Notholithocarpus densiflorus) grows in coastal forests in Oregon and California. Compared with the majestic redwood, it’s scruffy and small. But this humble hardwood plays an important ecological role in the redwood forest ecosystem. Its medium-height trees add a second canopy to the complex architecture of an old-growth redwood forest, creating more niches for diverse species. And its nutritious acorns feed bear, deer, rodents and birds. Learn more about this research.

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Researchers sampled coast redwoods' DNA at the Russell Research Station in Contra Costa County, California. Photo by Richard S. Dodd

Central California Redwoods More Vulnerable

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Researchers found in a 2007 study that coast redwoods’ genetic diversity was “very high” throughout the state, and more divergent in Central California. These Central California redwoods are most threatened by climate change and “should be a conservation priority,” said Richard S. Dodd, a professor of plant population genetics at the University of California, Berkeley. Learn more about this research.

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Emily Limm found that western sword fern absorbed the most moisture from fog. Photo by Emily Burns

Fog and Redwood Forest Plants

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Coast redwood forests depend on fog to survive the nearly rainless summers of California’s Mediterranean climate. It was once thought that redwoods captured this moisture through their roots. But a 2004 Save the Redwoods League-funded study proved that redwoods suck up water through their leaves as well. As a doctoral student at the University of California, Berkeley, Emily Burns set out to discover whether other plants in the redwood ecosystem were equally adept at “foliar uptake.” Learn more about this research.

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Photo by Sean Dreilinger, Flickr Creative Commons

Examining Coast Redwood Genes

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Genome science has made stunning advances in the past few decades. But until recently, no one had tried to sequence Sequoia sempervirens, the coast redwood. Part of the problem was the species’ complexity. Humans are “diploid,” meaning that for each chromosome, they have one copy inherited from their mother and one from their father. Redwoods, on the other hand, are “hexaploid,” meaning that they have three copies from each side, which triples the size of their genome. Learn more about this research.

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Fire is an example of a disturbance event that redwoods face.

Coast Redwoods’ Response to Disturbance Events

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In 2006, Save the Redwoods League recruited eight scientists to survey scientific literature about how coast redwood forests respond to “disturbance events” such as fires, windstorms and floods. The scientists considered how redwoods fit into two broad categories of trees: those that need major disturbances to perpetuate themselves and those that don’t. The seedlings of disturbance-dependent trees germinate in open spaces, grow quickly to outcompete other vegetation and tend to form even-age stands. Species that don’t need disturbances tend to be shade tolerant, slower growing and longer lived.  They usually grow in uneven-age stands. Learn more about this research.

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Wonder Plot.

Wonder Plot Study Tells Story of Development

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In 1923 Emanuel Fritz, then a Professor of Forestry at UC Berkeley, and Woodbridge Metcalf secured for study a one-acre grove of second growth trees along the Big River in Mendocino County. By that year, much of California’s old-growth redwood had been logged and a second generation of trees had begun to grow. Fritz and Metcalf intended to study tree growth on their plot in order to better understand just how a second growth forest develops. Learn more about this research.

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Core sampling. Photo by Peter Buranzon

Chemicals in Redwood Rings Indicate Past Water Uptake

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It’s no coincidence that redwoods live in the thickest part of “California’s fog belt.” The presence of coastal summer fog has long been regarded a necessary ingredient for the health and perpetuation of coast redwood ecosystems. During drier summer months fog supplies trees with moisture and blocks the evaporating rays of direct sunlight, reducing the amount of water that redwoods lose via transpiration. What’s less understood, however, is exactly how fog frequency has varied in the past century and how redwoods have responded to this variation. Learn more about this research.

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Canopy view of Jedediah Smith Redwoods State Park. Photo by Stephen Sillett, Institute for Redwood Ecology, Humboldt State University

What limits redwood height?

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In the upper reaches of their crowns, coast redwoods struggle to lift water and nutrients into their leaves. This struggle begins a process that limits tree growth, according to a team of researchers studying redwoods in Prairie Creek and Humboldt Redwoods State Parks. Learn more about this research.

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