Treesearch

The density and development of greenleaf manzanita, snowbrush, goldenbush (rabbitbrush), and graminoids were evaluated in a young California red fir plantation in northern California from 1986 through 1995. Manual grubbing and herbicides created treatment regimes that lasted for 3 to 6 years and vegetation recovery times of 4 to 10 years. The duration and timing of the grubbing and spraying operations constituted the treatments. Species response was mixed: greenleaf manzanita had higher average values of density, foliar cover, and height when time since disturbance was longest, snowbrush...

Forest Service expenditures for fire presuppression and suppression activities increased from $61 million in FY 1970 to $951 million in FY 1994. Yet, real (net of inflation) expenditures have not increased significantly since FY 1970, if FY 1994 expenditures are excluded. During any given year, 56 percent of suppression expenditures are spent on supplies and services, including aircraft and food, and 32 percent on salaries and wages. Weather, access, and firefighter availability and skills were key contributors to suppression expenditures. Real expenditures for fuel treatments have...

A 12-year-old ponderosa pine plantation on the Tahoe National Forest in northern California was mechanically treated with a Hydro-Ax in an attempt to increase the survival and growth of the planted seedlings. Other release methods were not feasible because the shrubs in the mixed-shrub community (greenleaf manzanita, mountain whitethorn, bittercherry, coffeeberry) were too large (3 to 5 feet tall) and well developed. Additional treatments were a chemical treatment, in which 2,4-D was applied to a portion of the study site that had been treated with the Hydro-Ax 1 year previously, and...

We evaluated the importance of epiphytic lichens in the nutrient cycling of a blue oak (Quercus douglasii) woodland in California. Each oak tree contained an average of 3.8 kg lichen biomass, totaling 590 kg per ha. For comparison, oak leaf biomass was 958 kg per ha. We compared tree growth, volume and composition of throughfall (rainfall falling though the tree canopy), litterfall, and soil nutrients under 20 trees from which we removed the lichens to 20 control trees. The removal of lichens had no effect on the growth of the oak trees, but it did influence nutrient cycling fluxes...

We measured patterns of spatial synchrony in growth and reproduction by oaks using direct acorn surveys, published data on acorn production, and tree-ring chronologies. The two data sets involving acorn production both indicate that acorn crops are detectably synchronous over areas of at least 500 to 1,000 km not only within individual species but among species that require the same number of years to mature acorns. Although no tree-ring data are available for California oaks, growth patterns among oaks elsewhere are statistically correlated between sites up to 2,500 km apart. These...

Key issues in encouraging forest management at the interface level in the oak woodlands are fire abatement, stand improvement, infection reduction, and hazard tree removal. The development of effective management prescriptions for stand improvement and economic returns provide guidance for homeowners, appraisers, and realtors. The purpose of this research project was to determine the effects of stand characteristics (e.g., structure, density and health) on the value of urban/interface forested properties. In this study, the forest characteristic coefficients were statistically significant...