silver-haired bat

Redwoods may offer bats a haven amid disease, rising temperatures

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Bats are a top conservation priority. Not only are these fascinating mammals vulnerable to climate change, but many species around the world are also falling victim to a fungal disease called white-nose syndrome. New research funded by Save the Redwoods League suggests that coast redwood forests may offer bats refuge from both of these threats.

Study Suggests Fires Increase Relative Abundance of Redwoods

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Researchers believe that fires burned through most redwood forests every six to twenty-five years; in other words, it was a normal occurrence. What is not normal, is the lack of wildfires in the redwood forest.

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.

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.

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.

High-severity treatments have boosted the growth of isolated giant sequoias in what is now Giant Sequoia National Monument. Photo by Rob York

Disturbances Benefit Giant Sequoias

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Being dwarfed by Earth’s most massive tree, the giant sequoia (aka “Sierra redwood”), fills you with wonder. It’s hard to believe that a living thing can be so enormous and old. It may be alarming to see these forests on fire, but research funded by your gifts shows that disturbances such as these actually are good for giant sequoias. Learn more about this research.

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.

In Mill Creek forest, tree removal experiments explored how to bring old-forest features (such as giant redwoods and diverse plants and animals) to young forests like this one as quickly as possible. Photo by Kevin L. O'Hara

Forest Restoration through Thinning

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For more than half a century, the Mill Creek region in Northern California produced lumber. After clear-cutting, too many seeds were planted, producing a forest in which too many young trees competed for light, water and other resources. Now, thanks to Save the Redwoods League, Mill Creek is protected as part of Del Norte Coast Redwoods State Park and is becoming a laboratory for redwood forest restoration. Learn more about this research.

Redwood Soil Microbes Can Adapt to Climate

Redwood Soil Microbes Can Adapt to Climate

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Coast redwoods need healthy soil and its tiny organisms to survive. So how will climate change affect the forests’ fungi and bacteria? A research team led by Professor Mary Firestone at the University of California, Berkeley, recently found a way to mimic what the future may hold. Learn more about this research.

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.

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.”

Study results showed that at better-watered sites (similar to this one in Humboldt County), redwoods were randomly distributed. Photo by Daniel Lofredo Rota, Flickr Creative Commons

Old Redwood Forest Restoration

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Old-growth redwood forests are prized for their biological and aesthetic riches. If you’re a land manager trying to restore lands where redwoods have been logged, the old-growth forest is the ideal to which you aspire. But how do you move toward old-growth characteristics most efficiently? Learn more about this research.

Growing New Giants Through Canopy Gaps

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It seems unfathomable that the tiny seedlings Rob York sowed among ash piles in a clearing at Whitaker’s Forest could someday grow to be among the largest creatures on earth. Yet these green specks grew into giant sequoias two years after seeds were strewn in canopy gaps. This species of titan tree has stagnated in regeneration efforts for nearly a century. York, along with his graduate advisor, John Battles, is working on unlocking the secrets to growing new giants. Learn more about this research.

Photo by yourmap, Flickr Creative Commons

Prehistoric Fires Not Caused by Understory Grasses

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Grassy fuels on the forest floor were not the cause of frequent prehistoric fires in giant sequoia (Sequoiadendron giganteum) groves, according to UC Berkeley researchers and California State Park ecologists.

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.

Big brown bat. Photo by Don Pfitzer, USFWS

Bats in Giant Sequoias

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Prior to this study, little was known about the bat community in Yosemite’s three giant sequoia groves and virtually nothing was known about how bats use the canopy in any of the Parks’ forests. Dr. Elizabeth Pierson, Dr. William Rainey, and Leslie Chow carried out major research to study bat roosting behavior in fire-scarred hollows at the base of sequoia trees, bat feeding behavior in association with a variety of habitats, and bat activity in the giant sequoia canopy. In addition, they combined observations from this study and others to describe the natural history of Yosemite’s 18 bat species. Learn more about this research.