Treesearch

Planted ponderosa pine (Pinus ponderosa Dougl. ex Laws. var. ponderosa) seedlings in young plantations in California are at a disadvantage compared with competing shrubs, forbs, and grasses. In many instances, roots of competing plants begin expanding and exploiting the soil earlier and in greater numbers, thereby capturing the majority of available resources and lowering pine survival and growth. Competition thresholds or "how much is too much?" are: for treatments where a cleared radius is prescribed, no weeds are acceptable within the space needed for maximum growth of pine seedlings...

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Least Bell's vireos (Vireo bellii pusillus) exhibit a high degree of between-year fidelity to breeding area. Use of many sites in an isolated population in Santa Barbara, California, spans at least 10 years. Males and females show different types and degrees of tenacity to territories, as well as to some nest-sites. More than 60 percent male and nearly 30 percent female returning birds utilized the previous year's territories. While pair bonds remain strong throughout the breeding season for most birds, mate fidelity may be determined by such factors as population size and its sex ratio....

Two dredge-spoil sites were revegetated on the lower Colorado River with native riparian trees. Another site was cleared of exotic saltcedar (Tamarix chinensis) and revegetated with native shrubs. Sites were censused for birds through all phases of revegetation. Bird species were grouped by natural-history characteristics to determine changes in the types of species occurring during the development of revegetation sites. Most species responded positively within 2 years after planting, including some sensitive species. This study is the first of its kind to document changes in bird use of...

This paper explores the tightness of the linkage between stream-dwelling salmonids and ripar ian vegetation. Comparison of original distributions of salmonid species with that of vegetation types shows that distribution within a given salmonid species is not limited to a specific vegetation type, and that different salmonid species cooccur within a given vegetation type. Examination of reported differences in trout production among streams appear to be related to differences in riparian setting only indirectly and insofar as these reflect differences in prey availability and, to a lesser...

The least Bell's vireo (Vireo bellii pusillus) is an endangered songbird inhabiting riparian woodlands in southern California. Although the species requires riparian habitats for nesting, vireos also occur in upland habitats adjacent to breeding areas. Vireos breeding at the Sweetwater River in San Diego County during 1986 and 1987 were observed using non-riparian areas for foraging and nesting. The use of non-riparian habitats, primarily areas of coastal sage scrub and chaparral vegetation, varied over the nesting cycle, and was related to territory location and habitat composition. These...

In December, 1986, nearly 4,000 riparian trees and shrubs were planted on 4 acres of floodplain land adjacent to Coyote Creek in Santa Clara County, California. To document changes in wildlife habitat characteristics of the revegetation area and surrounding habitats, an intensive wildlife monitoring program was established. Techniques employed included variable radius circular plot sampling for birds and mammals, live-trapping of small mammals, reptiles and amphibians, breeding bird censuses and mist netting of birds along established transect lines. This monitoring program is a joint...

Least Bell's Vireo (Vireo bellii pusillus) nesting sites on three rivers in coastal southern California were characterized to provide data for a habitat restoration plan for this endangered species. In addition, riparian areas outside vireo territories were sampled to compare with nesting habitat. The parameters measured were percent cover, percent open ground, plant heights, plant density, height class frequency, species frequency, and species diversity. The vireo nest sites showed no significant differences from the non-nest riparian sites for any of the variables studied. The nest sites...