Treesearch

Detailed information about the nesting habitats of birds, including those needed for successful nesting, can provide a better understanding of the ecological factors that permit coexistence of different species and may aid in conservation efforts. From 1989 through 1994, we studied the nesting habitat of secondary cavity-nesting birds in oak woodlands at the San Joaquin Experimental Range, Madera County, CA. We measured habitat surrounding nests and examined similarities and differences in nesting habitat used by eight species to evaluate overlap in nesting habitat use and possible...

We examined the use of hardwood tree species for nesting by bird species breeding in ponderosa pine (Pinus ponderosa) forests in the Sierra National Forest, California. From 1995 through 2002, we located 668 nests of 36 bird species nesting in trees and snags on four 60-ha study sites. Two-thirds of all species nesting in trees or snags used hardwoods for nesting, with 19 species using California black oaks (Quercus kelloggii) and 11 using canyon live oaks (Quercus chrysolepsis). Although hardwoods comprised only 17 percent of available trees, 51 percent of nests in trees were in hardwoods....

We used behavioral experiments to evaluate competition for nest sites and the extent to which European Starlings (Sturnus vulgaris) are seen as a threat by native bird species at the San Joaquin Experimental Range, Madera County, CA. We quantified the level of aggressive behavior of four species of native cavity-nesting birds to starlings at active nests in trees and nest boxes. In 2000, we presented a life-like model of a starling at active nests of native cavity-nesting species, placed in front of the nest opening. In 2001, a House Sparrow (Passer domesticus) model was used as a control,...

The negative effect of turbidity on the reactive distance of salmonids has been well established. However, determining the consequences of this relationship for overall feeding success remains problematic, as successful foraging by salmonids across a broad range in turbidity has been observed under a variety of conditions. Previous laboratory and field observations suggest that benthic feeding by salmonids in flowing water affects the turbidity dependence of foraging success. Two experiments were conducted in a laboratory stream to quantify benthic feeding success of salmonids across...

The ecological research project of interior ponderosa pine forests at the Blacks Mountain Experimental Forest in northeastern California was initiated by an interdisciplinary team of scientists in the early 1990s. The objectives of this study were to determine the effect of stand structure, and prescribed fire on vegetation growth, resilience, and sustainability of ponderosa pine ecosystem. Two stand structures were created with mechanical thinning on 12 units of about 100 hectares each. Low structural diversity (LoD) includes an even spaced, continuous canopy with few snags and few large...

A large-scale interior ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) study was conducted at the Blacks Mountain Experimental Forest in northeastern California. The primary purpose of the study was to determine the influence of structural diversity on the dynamics of interior pine forests at the landscape scale. High structural diversity (HiD) and low structure diversity (LoD) treatments were created with mechanical thinning on 12 main plots. Each plot was then split in half with one half treated with prescribed fire. During the 5-year period after the treatments, the LoD...

Ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) stands with late-seral features are found infrequently, owing to past management activities throughout western North America. Thus, management objectives often focus on maintaining existing late-seral stands. Observations over a 65 year period, of stands with not past history of harvest, showed substantial ingrowth in the smaller diameter classes and elevated raes of mortality among the largest mature trees in the stand. Adjacent stands, with combinations of thinning and prescribed fire, had far fewer high-risk mature trees and...

A diameter increment model is developed and evaluated for individual trees of ponderosa pine throughout the species range in the United States using a multilevel linear mixed model. Stochastic variability is broken down among period, locale, plot, tree and within-tree components. Covariates acting at tree and stand level, as breast height diameter, density, site index, and competition indices are included in the model as fixed effects in order to explain residual variability. The data set used in this study came from long-term permanent research plots in even-aged, pure stands both planted...

The western pine beetle Dendroctonus brevicomis LeConte (Coleoptera: Scolytidae) is one of the most damaging insect pests of ponderosa pines Pinus ponderosa Douglas ex P. & C. Lawson in Western U.S.A. We compared the effect of verbenone, a well known bark beetle anti-aggregation pheromone, with that of acetophenone on the attraction of D. brevicomis to its aggregation pheromone in a ponderosa pine forest in northern California. We tested the D. brevicomis aggregation pheromone alone and with three different release ratios of the aggregation pheromone (attractant) to verbenone or acetophenon...

In 1987, the Pacific Southwest Research Station (PSW) of the U.S. Department of Agriculture, Forest Service (USFS), chartered a research work unit to examine outdoor recreation in the wildland-urban interface. The need for the work unit was identified by the four forest supervisors in southern California, from the Angeles National Forest, the Cleveland National Forest, the Los Padres National Forest, and the San Bernardino National Forest. Supervisors wanted scientific information about the diverse outdoor recreation visitors who were using USFS lands for outdoor recreation.