Treesearch

A field experiment was conducted to examine the effects of soil water availability on blue oak (Quercus douglasii) seedling establishment. Acorns were planted either into cleared plots of 0, 10, 20, or 40 cm diameter. The cleared plots were located in two grazed and one ungrazed site. Half of the plots received drip irrigation in a split plot design. Soil water and plot size, depending on the site, and initial acorn weight and parent tree all influenced oak seedling growth. Survival and height in subsequent growing seasons was dependent on early growth. Soil water availability in the first...

Field performance was evaluated for blue oak (Quercus douglasii Hook. & Am.) acorns of different size classes (weights) and from different trees which produced predominantly small, medium, or large acorns. Emergence, height, and survival were monitored for two growing seasons. A parallel evaluation, mainly of root characteristics, was conducted in an observation growth box. Acorn size significantly influenced emergence, survival, and height the first year, and influenced height growth the second year. Large acorns produced taller seedlings with heavier total root weight. Acorn size also...

In 1988, a study was began to evaluate acorn yield of valley oak (Quercus lobata), coast live oak (Q. agrifolia), and blue oak (Q. douglasii) in three of California's central coast counties: Santa Barbara, San Luis Obispo, and San Benito. The purpose of the study was to examine the degree and variability of acorn production and factors, such as geographic location, individual tree differences, and land-use history, which may contribute to these differences. Data collected during autumn 1988 and 1989 indicate that acorn production was low on the three oak species surveyed; nearly 90 percent...

Hardwoods are disappearing from the California landscape at alarming rates. This is due to a variety of influences, both natural and man made. It is clear that conservation and rehabilitation of hardwood resources will require a large effort on the part of research institutes, universities, government agencies, special interest groups, private developers, maintenance workers and ordinary citizens. In order to study the problem and arrive at workable solutions, the author has developed computer assisted methods that help the researcher or land planner inventory, evaluate and manage the...

Size class distribution of Quercus engelmannii (Engelmann oak) on the Santa Rosa Plateau was studied to understand whether current recruitment of young oaks is sufficient to maintain the population in spite of high natural mortality and impacts of development in some portions of the plateau woodland. Sapling-size oaks (1-10 cm dbh) made up 5.56 pct, 4.17 pct and 6.58 pct of total trees sampled at hill (N=252), mesa (N=216) and valley (N=228) sites respectively where cattle were removed in 1986. Approximately 22.5 pct out of 200 trees sampled in an adjacent oak woodland (estimated to have...

Development of San Diego County has traditionally taken place on the coastal plain and in coastal valleys. Within the past two decades, it has spread into the foothills resulting in conflicts with oak woodlands. The County of San Diego has proposed a number of measures to protect oak vegetation including a tree protection ordinance, land use designations and zones designed to protect outstanding sensitive vegetation, and a brushing and clearing ordinance. The predominant method for preservation of oaks is through open space easements within subdivisions. This usually results in the...

Cattle have been faulted as a possible cause for poor oak regeneration in California's hardwood rangelands. This study sought to determine the effects of stock density and season of grazing on blue oak (Quercus douglasii) establishment. Year old blue oak seedlings were transplanted into annual grass/rose clover pastures at the Sierra Foothill Range Field Station. Steers were allowed to graze one plot per week at low, medium, and high stock densities (1, 3, and 6 steers/acre, respectively) during the months of January and April. Results from January indicate that low stock density does not...

This proceedings summarizes the research results presented at a symposium on oak woodlands and hardwood rangelands in California. Sixty-six papers are included, focused on six major topics, namely: regeneration and restoration of oaks, wildlife habitat considerations, monitoring trends, land use planning, management strategies, and ecology and management of Engelmann oak. These papers form the state of knowledge for this important ecological zone in California, and help to frame management, policy, and conservation strategies for this resource.

This paper outlines a mitigation program for pipeline construction impacts to oak tree habitat by describing the requirements for the Offsite Oak Mitigation Program for the All American Pipeline (AAPL) in Santa Barbara County, California. After describing the initial environmental analysis, the County regulatory structure is described under which the plan was required. The plan preparation and approval process is described, as well as how the plan was and is currently implemented in the field. The paper concludes with an assessment of plan objectives and recommendations for future mitigatio...

Annual rangelands produce 84 percent of California's range forage which are used all year by sedentary ranching operations and seasonally by migratory operations. Environmental policy, energy and water costs may reduce traditional summer forage sources, resulting in increased grazing pressure on hardwood and annual rangelands. However, the landowner's production goals and society's environmental quality goals can still be attained by subdividing the ranch into management units based on the land's productive potential and resource value and by intensifying grazing management. Pasture...