- Author: Jaime Adler
A special offer for you!
Oaks in the Urban Landscape: Selection, Care, and Preservation
Written by: Larry Costello, UCCE; Bruce Hagen, CAL FIRE;
Katherine Jones, Author
On Sale NOW through MAY 31st on the ANR Catalog
This publication offers a comprehensive look at the management of oaks in urban areas. As development moves into oak woodland areas, more and more oaks are becoming “urban” oaks.
Oaks are highly valued in urban areas for their aesthetic, environmental, economic and cultural benefits. However, significant impacts to the health and structural stability of oaks have resulted from urban encroachment. Changes in environment, incompatible cultural practices, and pest problems can all lead to the early demise of our stately oaks.
Using this book you’ll learn how to effectively manage and protect oaks in urban areas – existing oaks as well as the planting of new oaks. Three key areas are addressed: selection, care, and preservation. You’ll learn how cultural practices, pest management, risk management, preservation during development, and genetic diversity can all play a role in preserving urban oaks.
Arborists, urban foresters, landscape architects, planners and designers, golf course superintendents, academics, and Master Gardeners alike will find this to be an invaluable reference guide.
Working together we can help assure that oaks will be a robust and integral component of the urban landscape for years to come.
Health, Growth, Aging and Decline
Roots and Soils
Biotic and Abiotic Disorders
Structural Failures, Defects, and Risk Assessment
Oak Preservation during Development
Ordinances for Tree Protection
- Author: Jaime Adler
Using Genomic Tools to Manage Healthy North
American Oak Populations
Symposium and Workshop
June 24, 2011, Davis, CA 1-5 PM
Venue: Alpha Gamma Rho Room, Buehler Alumni and Visitor Center, UC
Victoria Sork, University of California, Los Angeles. Genomics as a
conservation tool for oak management
Susan Frankel, USDA- Forest Service, Pacific Southwest Research Station.
Overview of current threats to Oaks in the West
Richard Dodd, University of California, Berkeley. Potential use of
genomic tools for hybridization studies of oaks
Jessica Wright, USDA-Forest Service, Pacific Southwest Research Station.
Using transcriptomics to study oak pathogens
Sally Aitken, University of British Columbia. Using genomics to
understand forest responses to climate change.
Panel Discussion with resource managers from State, Federal, and Non-governmental organizations
No registration fee, but please RSVP by June 1, 2011.
A no-host picnic dinner will follow the discussion.
Organized by the North American Oak Genomics Working Group in collaboration
with the Conifer Translational Genomics Network and the International Symposium on Genomics-Based Breeding in Forest Trees
- Posted By: Jaime Adler
- Written by: Adina Merenlender, CE Specialist
California’s hardwoods have so many virtues it is difficult to count them all. Only recently scientists have come to appreciate the influence that living hardwoods exert on stream channel shape as the key to providing good habitat for all aquatic species, including salmon in coastal California streams. It is well known that wood in streams provides habitat for a broad range of fresh water species and can influence the shape of the stream channel and important ecosystem processes, such as moving sediment and nutrient cycling. Wood also provides important habitat for fish by creating pools, providing shade and hiding places from predators, protection from high flows, food and shelter for invertebrates, woodjams that store spawning gravels and organic matter, and facilitates riparian plant regeneration. Wood is considered one of the most important habitat components for anadromous salmonids and with salmon on the decline it is important we ensure the presence of wood in California’s coastal streams.
Previously, scientists attributed all of these qualities to large pieces of dead wood from species that rot slowly such as the infamous California redwoods. But this begs the question: What is happening in streams lined by hardwoods such as California bay laurel, live oaks, alders, and willows commonly found in our mediterranean-climate woodlands? Field research conducted by Dr. Jeff Opperman, UC Berkeley alumnus now working for The Nature Conservancy, in 20 stream reaches in the northern parts of the San Francisco bay area, documents that living hardwoods are playing an essential role in California’s hardwood dominated streams by providing permanent structure that interacts with stream flow and gravel movement to create essential aquatic habitat for salmon and other native species (Figure 1).
Figure 1. Extracted from OPPERMAN, J. J. and A. M. MERENLENDER. 2007 Living trees provide stable large wood in streams. Earth Surface Processes and Landforms 32:1229-1238 (a) A red willow (Salix laevigata) that has fallen into Wildcat Creek (Aladmeda County, CA) but remains rooted and living (photo taken looking upstream).The lower arrow indicates sprouts growing from the lower branch of the willow. The upper arrow indicates a branch that has reoriented to become the primary source of photosynthesis for the fallen tree. A channel-spanning wood jam has accumulated upstream of this willow, which has contributed to the formation of the pool in the lower left portion of the picture. (b) The shaded areas denote all the wood that is still living within this wood jam.
As you can imagine trees that fall or grow over the stream and remain rooted and alive are more stable over time and and can withstand sizeable storms. After falling into the stream, hardwoods can often sprout new branches or bend into new shapes that result in vertical branches to capture more light for photosynthesis. A live tree spanning a creek with leaves on vertical branches creates significant shade and captures additional wood and organic material all to the benefit of the fish living below (Figure 1). These persistent hardwoods provide important in-stream structure in streams with riparian corridors that lack large conifers. In fact, in the 20 streams Jeff studied living hardwoods were the key piece of wood within a wood jam, the primary mechanism by which wood in?uences channel morphology, and had greater influence on channel morphology than larger pieces of dead wood found. Only 74% of the wood jams without live wood persisted to allow for scowering and pool formation in the stream over 1-2 years while 98% with living wood as a key piece remained in place for longer. Wood jams that span the entire channel provide the greatest influence over stream morphology and create complex habitat that maintains cooler safer waters for fish. Out of all the channel-spanning jams measured by Jeff, 44% had a living hardwood as key piece (Figure 2).
Figure 2. Extracted from OPPERMAN, J. J. and A. M. MERENLENDER. 2007 Living trees provide stable large wood in streams. Earth Surface Processes and Landforms 32:1229-1238 The proportion of all wood jams with a live key piece (shaded), dead key piece (white) or no key piece (black), based on channel position of the wood jam.
Clearly, California hardwoods are a necessary component within California’s fresh water aquatic ecosystems because they contribute to ?sh habitat by creating and maintaining wood jams, forming pools, and providing cover. Unfortunately, wood in streams is often removed by landowners, in some cases to protect property, but in other cases because of the desire for a clean stream or for easily accessible firewood. To stress the importance of maintaining wood in streams for fish habitat I, along with Jeff, and David Lewis a UCCE Watershed Management Advisor for Sonoma County, wrote a free publication for landowners titled “Maintaining wood in streams: A vital action for fish conservation.” Please click here to access the publication and learn more about this topic: http://ucanr.org/freepubs/docs/8157.pdf.
- Posted By: Jaime Adler
- Written by: Douglas D. McCreary
As everyone who lives in California knows, this has been a fairly unusual year weather-wise. In the fall there was abundant rainfall, but this was followed by a January when the tap shut off almost completely. Then in March it started raining and snowing almost continuously and has only recently stopped. There was a week or two of warm weather, but now in mid-April, it has turned cold again. Here at UC’s Sierra Foothill Research and Extension Center in Yuba County, almost all of the oaks have now leafed out. The trees are especially beautiful at this time of year since it seems that each of the different oak species has a distinctive color of green. However this new foliage is quite tender and vulnerable to frost damage. Damage to new foliage occurred in Northern California three years ago when there was a late frost and many trees had their new foliage killed. Interestingly it seemed to only occur at mid elevations between 1000 and 2000 feet. At lower elevations, temperatures were not cold enough to affect the foliage and at higher elevations, the trees were phenologically further behind and hadn’t yet leafed out. Fortunately oaks have evolved under conditions where leaf damage regularly occurs (also as a result of low intensity fires or insect defoliation) and normally suffer little long-term damage from late freezes.
Another risk at this time of year is cattle poisoning. Oak trees contain toxic chemicals in newly emerging foliage, including tannins and phenols, that can be lethal to cows if the foliage is a very high percentage of their diet. A couple of decades ago there was a late spring snowstorm that happened after the oaks had leafed out. In addition to knocking many limbs and branches to the ground, the snow covered up available grass so there was little for livestock to eat besides the young buds and foliage. As a result, about 2,700 cattle died due to oak toxicity. In the unlikely event such conditions occur again, livestock operators can prevent lethal damage by feeding their animals hay or other supplemental feed when the natural grass is covered up. But it is important to start hay supplementation immediately and not to wait until cattle get sick or die. A delay of only a day or two can easily result in many more deaths and ill cattle. If cattle are in conditions where toxicity is a longer-term possibility, the use of calcium hydroxide in a supplement can prevent sickness. The addition of 10% calcium hydroxide (hydrated lime) to a supplement will still be palatable to cattle. Then if the cattle will consume about two (2) pounds of this supplement per day it will prevent many cases of oak toxicity. This supplemental calcium hydroxide has to be consumed before exposure to be effective.*
* Information about oak toxicity was gleaned from an article by UC Extension Veterinarian, John Maas in the January 2008 issue of California Cattlemen’s Magazine.
- Author: Richard B Standiford
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