Treesearch

A preliminary report of a statewide project investigating vegetation change in blue oak (Quercus douglasii) woodlands in California is presented. Vegetation plots taken in the 1930s, as part of a statewide vegetation mapping project, were relocated and surveyed. Species composition, cover and tree stand structure data from the earlier study were compared with the current survey to determine the changes that have occurred in these woodland habitats. Twenty one plots were surveyed from south San Benito and eastern Monterey county rangelands. Changes of note included a general increase in...

The range and abundance of valley oak (Quercus lobata, Nee) have steadily decreased in the last 100 years due to low rates of regeneration during this period. Documented low rates of sapling recruitment must be compared to adult mortality rates in order to evaluate the severity of this decline. The purpose of this research is to measure and analyze the mortality rate of established valley oaks in different habitat types over the past 51 years. Valley oak stands of the Santa Ynez Valley in Santa Barbara County were mapped and stratified into three major habitat types: valley floor alluvium,...

Valley oak (Quercus lobata Née) has exhibited inadequate regeneration since the last century. Seedlings become established, but few develop into saplings. We hypothesized that the invasion of alien annual grasses into native perennial grasslands has increased oak seedling mortality by decreasing soil moisture availability. We conducted greenhouse experiments to test if the alien annual grass Avena fatua L. and the native perennial grass Stipa pulchra Hitchc. differentially effect soil moisture and valley oak seedling growth. Results showed that valley oak seedlings in the A. fatua treatment...

We sampled characteristics of vegetation and estimated abundances of bird species on 23 plots representing a continuum of tree densities of the blue oak phase of the Coast Range foothill woodland near Hopland, California. Fifty-one bird species were found breeding. Cavity-nesters dominated the bird community in number of species and individuals. Cavity nesters used a variety of tree species for nesting, highlighting the importance of tree species richness. Large deciduous oaks were found to be important as granary trees for acorn woodpeckers, as well as substrates for nest cavity excavation...

Two Sierra foothill watersheds were monitored to learn what effects selective oak removal would have on watershed hydrology and water quality. We also used the data to generate sediment rating curves and evaluate the modified universal soil loss equation (MUSLE). Annual sediment rating curves better accounted for the variability in precipitation events from year to year, which may be at least as important as total rainfall, on the amount of runoff and sediment yield. Measurements before and after oak removal indicated small but not statistically significant increases in the runoff/rainfall...

The primary goal of this study was to find economical and effective planting techniques that will ensure the establishment and early survival of coast live oak (Quercus agrifolia Née) and blue oak (Q. douglasii H. and A.) in the Central Coast region of California. Eight treatments were evaluated ranging from unprotected seed spots to those protected by 1/4-inch hardware cloth exclosures. Planting was repeated for two years. Seedling establishment varied significantly among study sites and between planting years. Poor germination and survival was attributed to below normal rainfall before...

This paper describes monitoring hardwood rangelands in California within the context of an adaptive or anticipatory approach. A heuristic process of policy evolution under conditions of complexity and uncertainty is presented. Long-term, short-term and program effectiveness monitoring for hardwood rangelands are discussed relative to the process described. The objectives of monitoring include establishing baseline information about the extent, status and condition of hardwood rangelands throughout the state. Baseline information serves as a starting point for detecting change, evaluating...

The protection of seedlings from animal browsing is critical for the survival and growth of many tree species. This is particularly true in wildland areas and arid areas (McAuliffe, 1986), and oftentimes in urban areas. A variety of techniques and devices have been used to protect seedlings, from using straw stubble to milk cartons to plastic or metal screens. Recently, Tuley (1985) reported the successful use of "tree shelters" to protect oak seedlings in England. Tuley's tree shelters are essentially translucent plastic tubes (up to 6 feet in height and approximately 3 inches in diameter)...

Blue oak seedling mortality was studied in relation to vertebrate predators, initial acorn planting position, slope and aspect, and oak canopy cover at two sites in the Central Coast Ranges of California. Seedling survival rates (Psd) were related to treatment variables using logistic regression analysis. Analysis of 2842 seedlings for 3 years following establishment indicated that site, rodents and acorn planting position were important variables explaining seedling losses. Seedling mortality was six times higher in the savanna site than the north-slope forest apparently because of...

The pattern of land use and ownership—including sizes of ownerships, types of landowners, and their various management objectives—affects the level of benefits available from the California's hardwood resource. Geographic information system (GIS) databases of ownership and population characteristics were developed for two California counties using local assessors' data, Census data and existing vegetation maps. The utility of these spatial data sets is demonstrated in preliminary comparisons of hardwood land ownership patterns in Nevada and Shasta Counties. Refinement of these data capture...