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Hybrid oak trees muddle identification at California Naturalist Regional Rendezvous

Knowing the names of trees is a point of pride for many California Naturalists. So a walk among the diversity of oaks at the Pepperwood Preserve left many feeling humbled.

The three-hour excursion was part of the UC California Naturalist Regional Rendezvous in October at the 3,200-acre nature preserve nestled in the foothills between Napa Valley and Santa Rosa.

Excursion leader Steve Barnhart, academic director emeritus at Pepperwood, said there are 500 oak species in the world; 21 in California. But cohabitating on the rolling hills and valleys of the Golden State, many oaks have produced hybrids that combine characteristics, making identification challenging.

Steve Barnhart opens the 'Oaks of Pepperwood' excursion during the California Naturalist Regional Rendezvous.

Doctoral candidate Phrahlada Papper, who is studying oak tree genetics, said, “I'm of the mind that you shouldn't ever name an oak.”

Even the tan oak, long thought to be misnamed, is coming under new scrutiny.

“It's not an oak,” Barnhart said. “It has acorns, male and female flowers on the same stalk, but tan oaks are insect pollinated. True oaks are wind pollinated. Tan oaks are closer to chestnuts.”

But Papper raised his hand. “Genetically, it might be an oak,” he said.

Barnhart laughed. “So tan oak is up in the air. That's why it's so much fun to be in science,” he said. “I learned something today.”

Doctoral student Phrahlada Papper discusses oak tree genetics.

In popular culture, oaks are thought to be majestic, towering trees, with wide spreading branches. However, Barnhart said, most California oaks are shrubs, including the leather oak.

Leather oaks grow in serpentine soils and have the ability to produce two types of flowers, one in the spring and another quite different in the fall. Leather oaks are monoecious, they have both male and female flowers on the same plant. On a particular leather oak at Pepperwood, Papper was surprised to find male and female flower parts in one bract and surmised that weather patterns may be responsible.

“California has weird weather and with climate change, it's getting even more weird,” Papper said.

Leather oak details.

Papper believes tracking phenology, the cyclic and seasonal changes in plants, is an ideal citizen science project for California Naturalists. One such project underway at Pepperwood is led by Wendy Herniman. A University of Edinburgh, Scotland, master's student, Heniman is documenting the phenology of 10 Pepperwood oak trees: 2 blue oaks, 3 coast live oaks, 2 black oaks and 3 Oregon oaks.

“Pepperwood is looking at climate change. It's a designated sentinel site. We're monitoring fog, we have soil probes, and we're collecting all weather and climate information. We can tie that to phenology,” she said. “We're trying to find out if phenophases are changing.”

Understanding the changing phenophases is important, Barnhart said.

“Everything is connected,” he said. “If acorns are produced early, animals species that depend on the food source will be disrupted. You have imbalances in the timing of the natural world. With climate change, what are the effects we'll be seeing?”

Wendy Heniman talks about her research near a hybrid Oregon-blue oak.
 
The acorn shape is Oregon oak-like. The leaf contours are blue oak-like. The specimen is evidence of hybridization in oaks.
 
California native poison oak is also found on the Pepperwood Preserve. It is unpopular with humans, but birds like the golden berries.
A 15-year-old Douglas fir was mechanically removed to stop it from crowding a 50- to 60-year-old oak tree, Steve Barnhart said. Fire suppression is giving oak competitors like firs a greater foothold in oak woodlands. "Fire suppression was an unhealthy thing to do," Barnhart said.
Posted on Monday, October 16, 2017 at 1:30 PM
Tags: California Naturalist (15), oaks (3)

Houses likely burned from the inside out, says UCCE forest advisor

Fire damage from the 1991 Oakland Hills fire. Buildings can burn quickly if embers get inside and fall on flammable materials.

Preventing embers from getting inside may save homes

Photos and video of the Northern California communities that have been hit by wildfires this week show buildings reduced to ash. How could so many homes and businesses burn so quickly in Wine Country fires? Many houses that burned to the ground in the Northern California fires likely burned from the inside out, says Yana Valachovic, UC Cooperative Extension forest advisor for Humboldt and Del Norte counties.

Red hot embers carried on the wind can enter the attic via the venting. “In the case of the wind-driven fires on October 8, these fires created ember storms that blasted little coals into everything in their pathway,” Valachovic said. These embers also create small spot fires near the home that fuel new sources of embers.

Weather played a large role in these fires and generated a fire storm of embers that ignited grass, shrubs, trees and anything in its path. “While the landscape can be the fuse, the homes really can be the most burnable part of the landscape,” Valachovic said. “These embers likely lodged in the small spaces and openings of homes and buildings. A common location is for the embers to enter via attic venting or HVAC systems distributing little fires into the buildings.

“Embers also landed on receptive leaves, outside furniture, and other flammable materials outside the buildings that created fires adjacent to the buildings. Once enough buildings were engulfed in fire, the radiant heat of each building fire led to exposures on the neighboring buildings, creating a house-to-house burn environment.”

Embers carried on the wind can ignite dry plant material like pine needles and create more embers that may enter homes through vents.

Residents can reduce the risk of embers setting their house on fire by removing dry plants around the structure.

“These fires remind us that everyone in California could help the fire situation by managing the vegetation, leaves in the gutters and decks, newspaper piles, brooms and other flammable sources near to their houses now before they get the evacuation call,” Valachovic said. “If you are likely to have to evacuate soon, temporarily covering or sealing up the vents with metal tape or plywood can help harden your home to an ember storm.”

Steve Quarles, UC Cooperative Extension advisor emeritus, who spent his career studying fire behavior on building materials and around homes, created an online Homeowner's Wildfire Mitigation Guide at http://ucanr.edu/sites/Wildfire. Quarles, who now does research for the Insurance Institute for Business and Home Safety, demonstrates how embers can ignite and quickly engulf a house in flames in a video https://www.youtube.com/watch?v=IvbNOPSYyss. After the 3-minute mark, video shows embers drifting up and flying through a screened vent into the house, where they could ignite combustible materials in the attic resulting in fire starting on the inside of the home.

“If you have time to prepare your home, use the wildfire last-minute check list at http://disastersafety.org/wp-content/uploads/2016/07/IBHS-Wildfire-Last-Minute-Checklist.pdf,” Valachovic said.

Valachovic has co-authored publications in home survival in wildfire prone areas http://anrcatalog.ucanr.edu/pdf/8393.pdf and how landscape plants near homes can create more vulnerability to wildfire http://anrcatalog.ucanr.edu/pdf/8228.pdf.

Once these fires are extinguished, a more detailed analysis will be possible.

“Past wildfire events have shown that this is the common way homes in the wildland urban interface (WUI) burn, and this scenario was likely translated to the urban environment,” she said.  

Posted on Friday, October 13, 2017 at 10:54 PM
Tags: wildfire (27), Yana Valachovic (5)

A honey of an educational odyssey -- and you're invited

Honey: the handiwork of bees. (Photo by Kathy Keatley Garvey)
Show me the honey!

You've probably tasted wine in California's acclaimed Wine Country, but have you ever tasted honey in the nation's rapidly growing “Honey Country”—the University of California, Davis?

Now you can.

The UC Davis Honey and Pollination Center is hosting a Honey Sensory Experience next month so you can learn all about honey, taste honey varietals from all over the world, and hear what researchers are doing.

The Honey Sensory Experience is scheduled for Nov. 10-11 in the Robert Mondavi Institute for Wine and Food Science's Sensory Building on Old Davis Road. The course is for beekeepers, bakers, mead makers, honey lovers, packers, importers, professional buyers, honey producers, and "anyone who wants to gain expertise in the aroma of honey analysis," said Amina Harris, director of the UC Davis Honey and Pollination Center, which is closely affiliated with the Robert Mondavi Institute for Wine and Food Science and the UC Davis Department of Entomology and Nematology, part of the UC Agriculture and Natural Resources (UC ANR). "Over two days, expert teachers will guide participants through a unique tasting and educational odyssey."

The event revolves around a first-of-its-kind study in the United States. or the past nine months, the center has been working with a team of sensory experts and trained tasters in the sensory lab in the UC Davis Department of Food Science and Technology. The panel analyzed the flavor, aroma, color, pollen and nutrition of three varietal honeys with samples produced across the nation.

Honeycomb--made by the bees. (Photo by Kathy Keatley Garvey)

The center's goal is to create a description of each varietal honey's unique characteristics.

“We have about 300 varietal honeys here in the United States,” Harris pointed out. “Many aren't produced each year. And some years actually have a better crop than others. Our center's goal is to help consumers understand what each varietal honey should really taste like.”

Well-known varietals include orange blossom and clover honeys, although these are rarely pure varietals, Harris said.

“According to current honey labeling laws, the varietal listed on the label need only be the predominant floral source. Simply, a blended honey of 23 percent alfalfa, 25 percent wildflower and 25 percent cotton with 27 percent orange blossom can be labeled ‘Orange Blossom Honey.' Swap out the orange blossom for clover and you have a new varietal.” 

A honey bee sips nectar from an orange blossom. (Photo by Kathy Keatley Garvey)

Harris said the center is "ready to share our experiences. Together we will spend two full days tasting varietal honeys from the world over and investigating the bees' handiwork. It all starts with nectar.” 

The Honey and Pollination Center, at the forefront of honey sensory research, developed the first-ever Honey Flavor and Aroma Wheel. The wheel has been featured on National Public Radio, at the Smithsonian, and at tastings and specialty food conferences across the country.

With interest in honey is on the rise,  consumers are actively looking for intriguing varietals, said Harris, who has tallied 35 years of experience in the world of varietal honeys. “The Honey Sensory Experience is the perfect opportunity for consumers looking to better-understand how honey is developed—from the moment the honey bee collects the nectar, until the honey is on the supermarket shelf."

"The two-day program “will bring together a group of exceptional presenters to explain all the nuances from nutrition to flavor to cooking."

Amina Harris, director of the UC Davis Honey and Pollination Center, speaks Sept. 6 at the Western Apicultural Society's 40th annual conference, held at UC Davis. (Photo by Kathy Keatley Garvey)

In addition to Harris, the presenters will include Orietta Gianjorio, member of the Italian Register of Experts in the Sensory Analysis of Honey; Hanne Sivertsen, sensory researcher, UC Davis Department of Food Science and Technology; Amy Myrdal Miller, certified nutritionist and owner of Farmer's Daughter Consulting, Sacramento; Joyce Schlacter, certified quality control specialist and director of food safety and quality, Smitty Honey, Iowa; chef Mani Niall, owner of Sweet Bar Bakery, Oakland, Calif. and Extension apiculturist Elina Lastro Niño, based in the UC Davis Department of Entomology and Nematology.

Niall, known as “Baker to the Stars,” served as a chef to Michael Jackson and a chef for the National Honey Board in the 1990s. He is the author of the book, Covered in Honey: The Amazing Flavors of Varietal Honey.

Miller, a UC Davis graduate, is an “amazing nutritionist,” Harris said. She is a farmer's daughter, a highly regarded public speaker, published author, and founder and president of Farmer's Daughter Consulting, a privately-held agriculture, food, and culinary communications firm.

A honey bee heading for lavender. (Photo by Kathy Keatley Garvey)

The Honey and Pollination Center is sponsored by the Robert Mondavi Institute for Wine and Food Science and the UC Davis Department of Entomology and Nematology, part of the UC Agriculture and Natural Resources (UC ANR).

The course, which includes breakfast and lunch each day, is $625. To access the agenda and to register, see http://honey.ucdavis.edu/events/honey-sensory-experience-an-introduction.

Posted on Monday, October 9, 2017 at 1:49 PM

Carbon Neutrality Initiative fellows seek to reduce our carbon footprint

UC ANR's Carbon Neutrality Initiative fellows for 2017-18, are studying new sources of renewable energy and strategies to cut carbon emissions.

UC Berkeley doctoral candidates Jose Daniel Lara, Allegra Mayer and Carmen Tubbesing, UC ANR's Carbon Neutrality Initiative (CNI) fellows for 2017-18, are studying new sources of renewable energy and strategies to cut carbon emissions.

The UC President's Carbon Neutrality Initiative Student Fellowship Program, established in 2015, funds student-generated projects that support the UC system's goal to produce zero-net greenhouse gas emissions by 2025.

Jose Lara
Each fellow will receive $3,000 to fund their sustainability-themed project.

The 2017-18 CNI fellows:

Jose Daniel Lara of San Jose, Costa Rica, is a first-year Ph.D. candidate in the Energy and Resources Group at UC Berkeley. Lara aims to determine the feasibility of producing electric power from dead trees. To analyze the resources available from tree die-off, he will develop a method to simulate harvesting of dead trees and evaluate the cost of harvesting dead biomass for electricity production. These results will inform policies regarding the use of biomass feedstocks to generate electric power and help mitigate the consequences of massive tree die-offs in forest communities throughout California.

Allegra Mayer
Allegra Mayer of Palo Alto is a fourth-year Ph.D. candidate in the Department of Environmental Science, Policy, and Management at UC Berkeley. Mayer is studying the potential for storing carbon in grassland soils across California to reduce global temperatures. Allegra will combine laboratory incubations with a state-of-the-art carbon model (DayCent) to measure and predict the effect of compost applications on grassland soil. She will then apply these results to quantify the potential change in grassland productivity and soil carbon storage associated with compost amendments. This will allow her to model the impact of climate change on the carbon cycle at these sites. 

Carmen Tubbesing
Carmen Tubbesing of Redmond, Wash., is a fourth-year Ph.D. candidate in the Department of Environmental Science, Policy, and Management at UC Berkeley and a fellow in the Graduate Student Program in Extension. The recent California drought led to a massive tree die-off, particularly in the southern Sierra Nevada, that will have long-term impacts on forest carbon storage. To gain a better understanding of the impact of carbon from dead trees, Tubbesing will calculate forest carbon transfers from live tree pools to dead pools between 2012 and 2016.

 

Posted on Wednesday, October 4, 2017 at 8:30 AM

California agriculture contributes to and is impacted by climate change

Agriculture in California is on both sides of the climate change challenge. It is a sector that releases significant quantities of climate-warming greenhouse gases into the atmosphere. At the same time, it is vulnerable to the expected effects of climate change, including increased drought and flooding and more intense and longer heat waves.

Three review articles in the current issue of California Agriculture, the research journal of UC Agriculture and Natural Resources, summarize the state of knowledge on three topics at the intersection of climate and agriculture in California: agricultural resilience to climate change (“climate-smart” agriculture); cropland emissions of nitrous oxide, the most important non-livestock source of agricultural emissions; and opportunities for working lands to contribute to meeting state greenhouse gas targets.

Long-term research at the Century Experiment shows how soil management and irrigation practices can influence the resilience of agricultural systems to climate change.

The first article, Long-term agricultural experiments inform the development of climate-smart agricultural practices, discusses the research underway to incorporate resiliency in agriculture to extreme and unpredictable weather patterns induced by climate change.

The authors describe the “Century Experiment” at UC Davis. Established in 1992, the Century Experiment is a replicated research project that includes 72 one-acre plots planted to 10 different cropping systems. The plots will be monitored and data collected for a period of 100 years, but Californians won't have to wait that long to see results.

In the first 20 years, for example, testing has found that soil carbon increased significantly more in the organic tomato-corn system than it did in any other crops and management systems. Soil infiltration rates and aggregate stability were also greater in the organic than conventional tomato-corn system.

Soil amendments – such as agricultural and food wastes and winter cover crops – have led to increased soil carbon sequestration, higher infiltration rates and greater aggregate stability in the organic system, compared to conventional systems.

The authors believe maintaining healthy soils is a key to climate-smart agriculture. Properties such as porosity, water retention, drainage capacity, carbon sequestration, organic matter content and biodiversity all help to confer resilience to new pests, diseases and weather extremes brought on by climate change.

The second article, Nitrous oxide emissions from California farmlands: A review, presents the results of 16 California-based studies.

Nitrous oxide emissions are the largest direct source of greenhouse gases from cropland in California and nationally.

The studies reviewed in the paper indicate that the nitrous oxide emissions factor – the fraction of applied nitrogen that ends up being released as nitrous oxide – can vary widely depending on crop, irrigation method, climate and other variables. Accounting for these large differences is important in improving the accuracy of estimates of overall nitrous oxide emissions from farmland, and in designing measures to reduce those emissions.

Management practices, like those used on the no-till field shown here, can increase total soil carbon.

The final article, Review of research to inform California's climate scoping plan: Agriculture and working lands, covers the range of ways that California's diverse agricultural systems can contribute to meeting the state's commitment to reduce greenhouse gas emissions by 40 percent from 1990 levels by 2030.

Slowing farmland conversion to urban uses and reducing emissions from the intensive livestock sector appear to provide the best opportunities for agriculture-related reductions. About two-thirds of direct agricultural emissions are from livestock production, particularly the dairy sector (the largest sector of the state's agricultural economy by annual revenue).

Because of the dairy sector's comparatively large contribution to agriculture's greenhouse gas emissions, the authors expect it to be a primary target for state climate regulations and incentives for emission reduction. They note, however, that policies should account for the already high levels of resource efficiency at California dairies.

The best opportunities for reductions in emissions from livestock operations center on feed and manure management. A report submitted to the California Air Resources Board says it may be feasible for California to achieve a 50 percent reduction in methane emissions from dairy if supportive practices are taken. Such practices might include:

  • Switching from flush water lagoon systems to solid-scrape or dry manure management.
  • Covering manure lagoons to capture biogas.
  • Installing anaerobic digesters to capture and use methane.
  • Use pasture-based dairy management.

The Legislature recently approved using $99 million in funds from the state cap and trade program to support the expansion of manure digesters and other technologies designed to greatly reduce emissions from livestock operations.

The review article also discusses potential for reducing greenhouse gas emissions from agricultural land in California by engaging in farmland and rangeland preservation, improved soil and nutrient management, integrating and diversifying farming systems, employing alternative practices in rangeland management and producing energy with biomass.

Posted on Wednesday, September 27, 2017 at 9:14 AM

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