Restoration of Giant Sequoia: An Experimental Approach to Assessing Restoration Optionson
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.
The giant sequoia is known as a long-lived pioneer species. Previous studies have demonstrated it depends on relatively large natural disturbances such as fires and falling trees to create gaps and soil conditions appropriate for the growth of new seedlings. York knew that the current giants in a particular grove developed in the wake of a man-made disturbance; the trees dominating the canopy in Whitaker’s Forest germinated following an incident of intensive logging and burning in the 1870s. By carefully removing canopy trees, thereby creating gaps in the recovering forest, York’s research attempted to mimic natural forest disturbances to grow the next generation of giant sequoias. The question was simple: Which conditions gave the tiny seedlings the best chance of survival and rapid growth?
By sowing seeds and planting seedlings in various surroundings, York identified that giant sequoia seedlings grew better as gap size increased, but that growth did not increase above gap sizes beyond 0.2 hectares. The resource-rich environments in the centers of gaps led to rapid growth of seedlings. York also experimented with soil conditions that might encourage giant sequoia growth. Soil with ash, which might be found after a fire sweeps through a forest and clears gaps in the foliage, increased seedling growth. The differences were subtle, but those slight distinctions in juvenile performance might determine the success of a tree’s lifetime growth. Germination rates are low for giant sequoia — only 50 of 442 seed spots planted grew any seedlings — so these slight changes in conditions could affect the very survival of the species.
Giant sequoia regeneration is an issue in nearly all of the remaining groves in their small range on the western slope of the Sierra Nevada. “Given its extreme longevity, the current giant sequoia population can easily absorb a century of missing regeneration,” York explained of the trees that can grow for 3,000 years, “but the consequences of continued regeneration failures will increase dramatically with time.”
— Rob York’s work has been submitted for publication in Restoration Ecology.
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Growing New Giants Through Canopy Gaps
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.
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Old Redwood Forest Restoration
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Wonder Plot Study Tells Story of Development
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Prehistoric Fires Not Caused by Understory Grasses
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Thinning Speeds Recovery to Old-Growth
Dr. Christopher Keyes and Andrew Chittick have found that thinning—removing select trees in a second-growth coast redwood forest—speeds up the forest’s development of old-growth characteristics, which include tall and bulky trees, small gaps in the canopy through which sunlight can penetrate, trees of varying heights, thicker tree branches, understory shrubs and ferns, and healthy young saplings. Learn more about this research.
Land Use and Forest Conservation
Dr. Sarah Marvin, professor of Geography at the University of Oregon, has set out to understand how the shape of the land and its use by owners reflect the probability of a privately owned coast redwood forest being protected. The two questions she has asked are: “Are privately owned forests more likely to be protected if they are on bigger parcels?” and “Do traditional, rural land uses as opposed to traditional, residential land uses promote forest preservation?” Answers to these questions might help predict the likelihood of future, private redwood forest protection and—of logged forests—regeneration. Learn more about this research.
Chemicals in Redwood Rings Indicate Past Water Uptake
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Bigger and Older Often Means Better Habitat
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Big Trees: A Bank for Soil Bugs
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Bats in Giant Sequoias
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.
Redwoods to the Sea Forest Carnivore Tracking Project
From time to time, a resident in Humboldt County will submit a report claiming to have spotted a Pacific fisher or a Humboldt marten. Because Pacific fishers are rare, and because the Humboldt marten was previously thought to be extinct due to human influences such as trapping and logging in their old-growth conifer habitat, these animals remain barely documented. The Corridor from the Redwoods to the Sea, built as a passageway for wild creatures, appears to be prime location to spot small carnivores such as fishers and martens, but despite local accounts, the rare sightings remain unverified by scientists. Where have these small predators gone? Learn more about this research.
Buffer and Let Be
Dr. William Russell found that the negative effects of timber harvesting in riparian coast redwood forests lessen with respect to two conditions; (1) longevity of the forest and (2) wider no-cut buffer zones. Longer-lived forests and forests with wider buffer zones surrounding rivers show less harm from logging. Riparian buffers are strips of forest left on either side of rivers after logging that control the amount of sediment and nutrients filtering into the water. In recently harvested forests and ones with thin or no buffers, young tree crowns crowd the canopies, letting through less sunlight, deciduous hardwoods thrive, extra dead wood litters the forest floors, and exotic and disturbance-prone understory species invade. These alterations, in addition to affecting the physical structure of rivers, down the line cause higher levels of organic material to filter into them. Learn more about this research.
Humboldt Martens Need Old Growth
It’s likely that Pacific fisher (Martes pennanti pacifica) populations are well distributed in Northern California’s Redwood National and State Parks (RNSP) for the same reason that Humboldt martens (Martes americana humboldtensis) have disappeared, according to research done by Keith Slauson, William Zielinski, and Gregory Holm. Second-growth forest habitats that cover a majority of the park are fishers’ sweet and martens’ sour. Learn more about this research.
Wandering Salamanders Choose Direct Route to Good Food
Wandering Salamanders (Aneides vagrans), in addition to dwelling on the ground, have been found in high-up patches of humus moss mats in trunk crotches, on limbs, under bark, and in the cracked and rotting wood of coast redwood trees. They may inhabit forest canopies, the researchers of this study speculate, because of a more profitable food resource available there. Learn more about this research.
What limits redwood height?
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Sponge-like Mats Make Good Habitat in Redwood Canopies: Wandering Salamanders Benefit
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Giant Sequoia Ecology Cooperative Web Site
Finding scientific resources on a specific plant species like the giant sequoia can be a daunting task. From the tangled network of information on the World Wide Web, the Giant Sequoia Ecology Cooperative Web site provides quick resources, ranging from maps and informational documents to expert contacts, which link the world to data on this rare tree, found only along the western slopes of the Sierra Nevada. Learn more about this research.
Balanced Management of Giant Sequoias
Giant sequoias are sometimes simply referred to as “big trees” and with good reason: They are the largest trees by volume and among the largest living things on Earth. These massive trees do not function in a void; they are supported by an intricate network of natural processes that keep the ecosystem working properly. Learn more about this research.
Epiphytes Provide High-Up Base for Biodiversity
William Ellyson and Stephen Sillett found evidence that demonstrates that epiphytes—plants that use other plants for mechanical support—play a crucial role in maintaining the biodiversity of redwood forest canopies. It’s well known that these hangers-on thrive in the old-growth Douglas-fir forests of Oregon and Washington, in places amassing the weight of two concert grand pianos per acre. Ellyson and Sillett reveal in this study that Douglas-fir has a rival in Sitka spruce, a tree that grows in and among northern coast redwood forests and supports a shockingly high diversity of epiphytes. Learn more about this research.
Bigger Preserves Have Better Chance to Prevail
Dr. William Russell, Dr. Joe McBride, and Ky Carnell have found that old-growth coast redwood forest reserves with areas larger in proportion to the length of their perimeters suffer fewer negative effects from exposed edges. Learn more about this research.
Bibliography Provides Easy Access to Coast Redwood Research
Coast redwoods have captivated scientists since their discovery, and thousands of articles, dissertations, and books have been written in an attempt to decipher various aspects of these magnificent trees. Finding all of this information was considerably more challenging until Deborah Rogers, a research geneticist and conservation biologist with the Genetic Resources Conservation Program at the University of California, Davis, stepped in to organize a bibliography of scientific materials written about coast redwoods in the past 50 years. Learn more.