Treesearch

Throughout the symposium it seemed that whenever the toughest problems were mentioned, people and their growing impact on the oak woodland ecosystem were at the source. This refrain was heard from nearly every keynote speaker, many of whom claimed that the oak woodlands were currently under the greatest pressure from urbanization. The needs and demands of landowners, stakeholders, and society-at-large were the topic of the Economics, Policy, and Planning technical session.

In July 1992, wildfire burned 500 acres of rural lands owned by Stanford University. Within the fire zone are five plots, ranging in size from 0.1 acre to more than 1 acre, on which nearly 600 naturally established juvenile California oaks (Q. agrifolia, Q. douglasii, and Q. lobata) have been monitored since 1990. Surveys following the fire revealed that although 32 percent of the oaks up to 10 inches tall died, only 9 percent of the oaks taller than 10 inches died. Twenty-two percent of all juvenile oaks were topkilled, but 22 percent of those resprouted in years following the fire.

The incidence and severity of Phytophthora cinnamomi Rands root disease was quantified in cork oak (Quercus suber L.) roots subjected to low oxygen (hypoxia) stress. Seedling root tips were inoculated with mycelial plugs of the fungus and incubated in ≤1, 3-4, or 21 percent oxygen for 5 days. Ninety-four percent of roots became necrotic in the ≤1 percent oxygen treatment, compared to 60 and 46 percent in the 3-4 and 21 percent oxygen treatments, respectively. Root colonization and necrosis did not differ significantly between treatments. Fifty percent of inoculated roots remained asymptomat...

In many parts of California, the rate and progression of land use change in the hardwood rangeland depend upon the decisions of ranchers. As major landowners in these regions, a rancher’s decision to subdivide or sell for development are significant moves toward land use change. In many instances, a single landowner decision may effect the disposition of thousands of acres of hardwood rangeland. This study seeks to identify factors that contribute to the sales or subdivisions of ranches in two rapidly developing counties in the Central Sierra Nevada: El Dorado and Amador. Area ranchers...

Rooting characteristics were compared in blue (Q. douglasii), valley (Q. lobata), and cork oak (Q. suber) seedlings under hypoxic (low oxygen) conditions. A 50 percent reduction in root growth occurred in all species at an oxygen level of 4 percent, or an oxygen diffusion rate of 0.3 mg cm-2min-1. Blue oak formed few lateral roots regardless of oxygen level, but valley and cork oak root production decreased under hypoxic conditions. Four percent soil oxygen might be viewed as a minimum requirement for sustaining root growth of oaks in the field, and differences in root branching morphology...

The California Oak Disease and Arthropod (CODA) host index database is a compilation of information on agents that colonize or feed on oaks in California. Agents in the database include plant-feeding insects and mites, nematodes, microorganisms, viruses, and abiotic disease agents. CODA contains summarized information on hosts, agents, information sources, and the details of the host-agent interaction. Most of the 853 insect pecies in CODA are in the orders Lepidoptera, Coleoptera, Hymenoptera, and Homoptera. About 40 percent of the 378 species of fungi in CODA are pathogens. Of these,...

The Contra Costa Water District’s (CCWD’s) Los Vaqueros Reservoir Project will inundate 180 acres of valley oak habitats. Instead of using replacement ratios to identify mitigation needs, we designed an approach that would efficiently replace lost ecological values. We developed a habitat quality index model to assess the value of lost wildlife habitat and effectiveness of mitigation options. Application of the model indicated that restoration of 238 acres of woodland and savanna would fully replace lost habitat values in 75 years.

California’s hardwood rangelands cover 10 million acres, providing wildlife habitat, esthetics, recreation, and watershed protection. About 85 percent of the area is privately owned, and private ranchers supply most of these open space values. The important public values from these privately-owned wildlands has created pressure for the state to regulate oak harvest and conversion. However, current policy calls for a program of intensive educational outreach. This program, started in 1986, is known as the Integrated Hardwood Range Management Program (IHRMP), and is a partnership between the...

Demand for non-timber forest products (NTFPs) is increasing, and growing numbers of people are enhancing their incomes by harvesting NTFPs from the wild. If forest ecosystems are to continue to produce NTFPs in the long run, harvesters must learn how to gather them in ways that minimize harvest damage to woods and wildlife. This guide, developed in a collaborative, information-sharing effort with harvesters, non-governmental organizations and USDA Forest Service employees, provides guidelines for sustainable harvesting of 24 NTFP plant species found in the Hayfork Adaptive Management Area...