Posts Tagged: Sierra Nevada
Since 2006, a team of University of California Agriculture and Natural Resources scientists has been studying the effects of vegetation management in the Sierra Nevada forest on fire behavior, forest health, water quality and quantity, the Pacific fisher (a small mammal in the weasel family) and the California spotted owl. The researchers are writing up their final reports and seeking public feedback on their recommendations and next steps in the process.
On Wednesday, May 27, community members are invited to discuss the recommendations with the Sierra Nevada Adaptive Management Project (SNAMP) team at an all-day meeting in the Sacramento area.
“Although adaptive management as a theory of practice in resource management has been in the literature for decades, few studies have been done to truly apply theory to actual practice,” said Susie Kocher, a UC ANR Cooperative Extension forestry and natural resources advisor for the Central Sierra area.
The US Forest Service's 2004 Sierra Nevada Forest Plan Amendment calls for managing the 11 national forests in the Sierra Nevada using the best information available to protect forests and homes. SNAMP is designed to provide resource managers with research-based information for making forest management decisions.
The SNAMP meeting will be held 9 a.m. to 4 p.m. on May 27 at the Wildland Fire Training Center, 3237 Peacekeeper Way in McClellan (near McClellan Airfield outside Sacramento).
To attend, please register at http://ucanr.edu/snamp2015annualmeeting by Sunday, May 24. Registration is free.
For more information about the project, visit http://snamp.cnr.berkeley.edu. The final SNAMP report will be available for download at http://snamp.cnr.berkeley.edu/snamp-final-report. Comments will be accepted online at http://ucanr.edu/snampreportcomments until July 15.
Besides their beauty, aspen groves are valued for providing myriad ecological services. The groves add species and landscape diversity to the Sierra Nevada. They offer higher water retention than the adjoining conifer forest, plus wildlife habitat and forage for livestock and wildlife.
Aspens are native to the Sierra Nevada and other areas with cool summer temperatures. Groves are typically clonal colonies that grew from a single seedling and spread when roots come to the surface and start a new tree. Each tree lives 40 to 150 years above the ground, but the root system can be much older; one colony in Utah is said to be 80,000 years old.
In the Sierra Nevada, aspen stands have been declining in vigor and sometimes died because of pressures from encroaching conifers, according to Malcolm North, research scientist with the U.S. Forest Service's Pacific Southwest Research Station in Davis.
Aspens thrive in bright sunlight. Without regular fires, conifers eventually shade them out. More than 90 percent of aspen stands in forested areas of California have some conifer shading. Removing conifers with mechanical equipment to increase sunlight in aspen groves is an effective technique to restore stands, but land managers have been reluctant to thin out conifers because of concern about impacts on nearby mountain streams.
A recent collaborative research project involving UC Cooperative Extension, UC Davis and the U.S. Forest Service confirmed that conifer removal to restore aspen stands can be conducted without degrading aquatic ecosystems.
Kenneth Tate, UCCE specialist in the Department of Plant Sciences at UC Davis. Research was underway from 2003 to 2010 and published in the December 2013 issue of the journal PLOS ONE.
“This project is an excellent example of the value of collaboration between the university, U.S. Forest Service, and stakeholders to integrate best management practices and best available science for the restoration of critical habitats in our national forests,” Tate said.
The scientists evaluated two aspen restoration projects next to mountain streams in the Lassen National Forest. Prior to conifer tree removal, they evaluated stream temperature, water quality, stream shade, overstory tree canopy cover, aquatic insects, soil compaction and soil moisture. Followup data collection took place two to seven years after the conifers were removed from the stands.
Water quality did not change following the timber harvest. Removing conifers reduced canopy cover, which resulted in an increase of sunlight on the stream, but there was no corresponding increase in water temperature. Soil moisture increased in stands where conifers were removed, compared to aspen stands that were untreated.
“It is a real win-win when we can use contemporary timber management strategies to restore aspen in the absence of a natural fire regime, and also safeguard the health of our aquatic ecosystems,” Tate said.
An aspen stand released from conifer encroachment. The fallen conifers are in the foreground.
Susie Kocher, UC Cooperative Extension advisor in the Central Sierra office.
“The fire interval is completely out of whack compared to pre-settlement conditions,” Kocher said.
In a historical, natural and healthy fire regime, nearly half of Sierra forests would experience fire every 12 years and three-quarters would burn every 20 years. However, only 0.2 percent of Sierra forest land has burned repeatedly at least every 20 years in modern times, while 74 percent has not had a single wildfire or prescribed burn in the last 103 years.
These conclusions are part of a report Kocher produced for the Sierra Nevada Conservancy, a state agency created by the California legislature in 2004 with the understanding that the environmental, economic and social well-being of the Sierra Nevada and local communities would benefit from an organization providing strategic direction.
SNC commissioned reports about Sierra Nevada indicators, such as Demographics and the Economy, Land Conserved and Habitat, and Water and Air Quality and Climate. Kocher’s report is titled Forest Health and Carbon Storage. Future system indicator reports will cover Fire Threat and Agricultural Lands and Ranches.
Forest health is a particularly difficult indicator to frame and quantify as there is no consensus on exactly what defines forest health, Kocher writes in the introduction.
“Forest health is a concept that is commonly used but not well defined,” Kocher said. “You’d think you’d be able to answer how healthy a forest is in a straight forward way. But you have to look at stressors, the natural processes that are happening in a forest. What does the landscape look like?”
Because forest health cannot be characterized by any single, simple measure, Kocher selected three data sets to provide an indication of the health of forests in the region: fire return interval, wildfire threat to ecosystems and forest pest impact and threat. She found that fire return interval told the most provocative story.
Fire return interval tracks the frequency with which wildfire revisits the same land over and over. Kocher compared the frequency of fire return between the pre-settlement “natural” state and modern times.
The pre-settlement or “reference” fire return interval is an estimate of how often, on average, a given forest type likely burned in the three or four centuries prior to Euro-American settlement in the middle of the 19th century. As such, the reference state includes fires deliberately set by Native Americans to manage forest vegetation and wildlife.
Researchers determined fire frequency by analyzing fire scars in tree rings of live and dead trees. Results show that forested areas previously burned every 11 years on average in the warmer and drier lower elevation forests such as ponderosa pine. On the other end of the spectrum, fire occurred only every 133 years for sub-alpine forests where it takes much longer for fuels to accumulate and dry.
Fire suppression in the last 100 years has left much of the Sierra forest land vulnerable to high severity wildfire, Kocher wrote in her report. High severity wildfire across wide areas poses a threat to forest plant and animal life, to forest communities and watershed function, particularly in the northern half of the Sierra Nevada Conservancy Region.
Kocher’s report also reviewed carbon storage in Sierra Nevada forests. Since carbon in the atmosphere is leading to global climate change, there is increased interest in storing carbon in forests.
“It could be said that by suppressing fire, we have sequestered more carbon,” Kocher said. “In an overstocked forest, there are more standing trees and more fuel on the ground. Storing more carbon may help in the short run, but in the long term, your stand has a higher risk of burning up. That puts a lot of carbon into the atmosphere.”
Forest thinning improves the stability of carbon storage in the long-term. Whether it reduces the amount of carbon stored depends on what factors are taken into consideration, Kocher suggests. Part of the complexity of the equation stems from whether or not forest products removed from the forest are factored in. Most studies that account for the carbon sequestered by lumber and other products removed during thinning find that thinning both increases the quantity and stability of carbon sequestered by forests over time.
But what kind of research could go through hundreds of socks a month? After years of experimentation, the research team has determined that socks are the ideal receptacle for hanging fisher bait in trees. The researchers are going through 250 pair a month, at a considerable cost, to create the “chicken in a sock” bait stations.
Besides the cost, chief scientist Dr. Rick Sweitzer is spending too much time in the Wal-Mart checkout line with a cart full of socks.
The scientists don’t need new socks; they would prefer old, unmatched, non-holey ones, something every American has cluttering up their sock drawers. You know the ones!
So, in an effort to reduce, reuse and recycle, the SNAMP wildlife research team is putting out a call for lost and lonely socks. Socks may be delivered or mailed to 40799 Elliott Dr., Oakhurst CA 93644. For more information contact Anne Lombardo at firstname.lastname@example.org. To read more about the research project visit the SNAMP website.
Other wildlife are also attracted to the bait stations:
The giant sequoias of the Sierra Nevada are the biggest and among the oldest trees on the planet. Some are 2,000 to 3,000 years old. Forestry scientists from the University of California and Cal Poly, San Luis Obispo, want to learn more about how disturbance factors affect the health of these aging behemoths.
Growth-response studies to date show that tree vigor can increase following moderate intensity disturbances such as prescribed fire or mechanical fire-hazard reduction treatments. Less certain, however, is how giant sequoias respond to lower and higher intensity disturbances. This information is of critical importance to identify the tradeoffs involved in fire prevention treatments or evaluating management options.
This summer scientists will visit native groves within Giant Sequoia National Monument, where high-intensity disturbances occurred 20 years ago. Harvests conducted at that time removed all trees except for large giant sequoia, creating a forest structure similar to what you’d expect after a high-intensity wildfire. Following the harvests, there was considerable public concern over the fate of the giant sequoias remaining. Mortality and growth in these areas has not been assessed until now.
The primary investigator on the project is Robert York, station manager of the UC Center for Forestry and an adjunct professor in the UC Berkeley Department of Environmental Science, Policy and Management. York is an expert in giant sequoia ecology. His co-investigator on the project is Scott Sink, a professor in the Department of Natural Resources at Cal Poly, San Luis Obispo. He has investigated differences between old growth and secondary forests and developed expertise in measurements of tree ring growth. The researchers will partner with forest ecologist Steve Hanna of Giant Sequoia National Monument in Porterville.
The scientists will also study tree ring widths taken from 33 giant sequoias at the UC-Whitaker Forest, where light burns and small tree removal occurred in 1967. York previously conducted field work on growth response in a giant sequoia forest subjected to a moderate-intensity disturbance. In addition to publishing a journal article on this work, researchers will hold a field trip for managers of giant sequoia groves, involve UC and CSU students in field and laboratory work, and develop a lab module for coursework at UC Berkeley.
The project is funded by a $10,000 grant intended to foster collaboration in higher education in California on issues affecting agriculture, natural resources or human sciences. In their grant proposal, the researchers said: “We have a unique opportunity to measure growth response in giant sequoia to these different levels of disturbance intensity, and therefore improve our understanding of this species’ complex life-history strategy, while informing management within giant sequoia groves.”