Treesearch

The University of California's Wildland Resources Center has established a new program of forest gene conservation to ensure that California's rich and diverse forests maintain their vigor and productivity in the face of human activities. At an international level, conservation biologists recognize the importance not only of protecting rare species from extinction by safeguarding habitats, but of caring for the genetic diversity of established forests. In some parts of the world past neglect, insufficient knowledge of genetics, and indiscriminate forestry practices have resulted in forests...

The locations and characteristics of five, small, previously undescribed stands of bishop pine (Pinus muricata) in central Marin Co., California, are reported. Three stands lie on dry sites in the Kent Lake Drainage north of Mt. Tamalpais: San Geronimo Ridge, a spur ridge above Little Carson Cr., and Oat Hill. These stands are anomalous in occurring 15 km from the ocean and up to 435 m in elevation. The remaining two stands are on rocky, dry sites on the west slope of Bolinas Ridge, near the McCurdy Trail, and south of Wilkins Gulch. Trees of all stands have slower growth, more spindly...

Of the seven pines that compose subsection Oocarpae (Little and Critchfield) in the genus Pinus, only the three Californian species form a coherent group, while the other four differ from each other and from the Californian species. Traits of the Californian species (Pinus radiata, P. muricata, P. attenuata) vary in complex geographic patterns, a situation that has led to nomenclatural confusion. Modern studies of genetic variation clarified some relationships among the taxa and uncovered other new problems. The taxonomic history and present status are reviewed and discussed. Monterey pine...

In a search for competition, limiting factors, and other patterns in a community of small passerine birds in Hawaii, we recorded the foraging behaviors, resource abundances, and climatic variables believed to influence resource levels. Some definite patterns were found, showing that the rare, endangered birds were specialists; however, some specialists were quite abundant. We also identified some potential competitive interactions by an introduced species; however, no overriding theme of organization was apparent. Rather, each species appeared to have its own suite of adaptations, largely...

Many young, understory Jeffrey pines (Pinus jeffreyi Grev. & Balf.) were found to be infected by western dwarf mistletoe (Arceuthobium campylopodum Engelm.) on Laguna Mountain, Cleveland National Forest, in southern California. Under heavily infected overstory, about three-fourths of the young pines (about 15 years old on the average) were infected by dwarf mistletoe. Infections per tree averaged about two and a half, two-thirds of these on the bole. Attempts to regenerate Jeffrey pine under an infected overstory in southern California will probably lead to a severely infected and damaged...

Two mathematical models are given to determine the best locations for initial attack resources in terms of travel time: a linear programmingmodel and a statistical model. An example for the Clearwater National Forest in Idaho illustrates some of the differences between the two models.

Using a Vegetation Drought Index (VDI) for estimating the susceptibility of California red and white firs to the fir engraver beetle (Scolytus venttralis) was evaluated in northern California forests where these true firs (Abies species) occur in mixed conifer and true fir stands. Midway through the summer drought, true fir moisture stress–a known predisposing factor–was highest on sites with highest VDI values (most xeric). In mixed conifer stands, the susceptibility of white firs–as indicated by the mean percentage of their basal area killed annually–was highest on sites with highest VDI...

Each of five insecticides was applied at two or three application rates by helicopter to 20-ha plots. Effectiveness of each application rateagainst eastern spruce budworm (Choristoneura occidentalis) was judged by comparing larval population reduction at 15 or 20 days aftertreatment against populations in untreated check plots. Performance of each insecticide was then compared with the levels of control normally obtained with two registered insecticides, carbaryl and acephate (90 + pct) usually used for western spruce budworm control. Maximum populationreduction from sulprofos (58 pct),...

The distribution of snags by tree species in the eastern Sierra Nevada of California generally reflects the associated timber type. Where present, however, lodgepole pine (Pinus contorta Dougl.) forms a large proportion of the snags present. Few snags of any species were present in the Jeffrey pine (P. jeffreyi Grev. & Balf. in A. Murr.) timber type in a study at Sagehen Creek Basin, in Nevada County. Simple regression analysis showed weak but significant relationships betweensnag density and canopy height, canopy cover, and slope. Multiple regression analysis were also weak, but revealed...

Overstory removal cutting, the most common means of converting old-growth stands to young growth stands in California, can produce excessive residues that pose management problems. Utilization is an attractive option for managing residues. However, the cost of residue retrieval and utilization is often prohibitive. Residue retrieval by a private contractor was studied to determine production rates and effectiveness after overstory removal on three blocks in true fir stands in northeastern California. Residues were inventoried before and after residue retrieval to determine the amount...