Treesearch

We report streamwater nitrate (NO,) concentrations for December 1995 to September 1998 from 19 sampling sites across a N deposition gradient in the San Bernardino Mountains. Streamwater NO3- concentrations in Devil Canyon (DC), a high-pollution area, and in previously reported data from the San Gabriel Mountains 40 km northeast of Los Angeles, are the highest values reported in North America for undisturbed forest or shrub land watersheds. Concentrations in the primary stream draining western DC peaked at 350 μmol L-1 in December 1997 and minimum base flow NO3- concentrations were nearly...

The effect of early and delayed release treatments (designated as "Treat first 3 years" and "Treat second 3 years," respectively) on diameter, height, and foliar cover of ponderosa pine seedlings, and density, foliar cover, and height of competing vegetation was evaluated in a young northern California plantation. Manual grubbing created vegetation recovery times (the period of time from the last release treatment until the end of the study) that lasted 4 to 10 years. Duration and timing of the grubbing operations constituted the treatments. Development of species other than the planted...

Sympatric coastrange sculpin, Cottus aleuticus, and prickly sculpin, C. asper, occupied distinct habitats in the mainstem Smith River, northwestern California. For example, 90% of coastrange sculpin (n = 294) used habitat with water velocity > 5 cm s -1 , whereas 89% of prickly sculpin (n = 981) used habitat with water velocity ? 5 cm s -1. Sixty-five percent of coastrange sculpin were found at depths < 1 m, whereas 37% of prickly sculpin occupied depths > 7 m. The strong spatial separation of coastrange and prickly sculpin in the mainstem Smith River contrasts with the overlap in their...

On a site of above-average quality in northern California, an early shrub-forb-grass plant community was treated by artificially seeding two forage grass species at plantation age 3, cattle grazing with and without seeded grasses, and applying a soil-active chemical (Velpar). Planted ponderosa pines were part of this community. Results for a 10-year period (1988-1997) are presented for planted pines, manzanita, other shrubs, forbs, and grasses (natural and seeded). In general, the pines, manzanita, and grasses were numerous and developing well after 10 years, and the other shrubs and forbs...

Most of the old-growth redwood (Sequoia sempervirens) in Calfornia has been cut; regenerating forests will probably never resemble those that were harvested, and what old growth remains on private land occurs in small, isolated remnant patches. The landscapes in which these stands occur differ so markedly from their original condition that their value as habitat to many species of wildlife, including bats, is unknown. Previous research in unfragmented redwood forests demonstrated that bats use basal hollows in oldgrowth redwoods as roosts. We sought to determine whether bats use similar...

Pinus sabiniana Dougl. (grey pine) forms savanna forests in the foothills surrounding California’s Great Central Valley. However, its fossil record, which dates from the late Miocene through the Pliocene and Pleistocene, is found exclusively in southern California, south of the species’ present range. A total of twenty-nine isozyme loci, representing eighteen enzyme systems, was assayed to analyse the genetic structure in eight populations of grey pine and attempt to track its migration history from southern to northern California. Expected heterozygosity in the two southernmost samples...

Mexico City experiences some of the most severe air pollution in the world. Ozone injury has been documented in sensitive tree species in urban and forested areas in the Valley of Mexico. However, little is known of the levels of other atmospheric pollutants and their ecological effects on forests in the Valley of Mexico. In this study bulk throughfall deposition of inorganic nitrogen (N) and sulfur (S) was measured for one year at a forested site upwind (east) and downwind (southwest) of Mexico City. Edaphic and plant (Pinus hartwegii Lindl.) indicators of N and S nutrient status were...

Response to the following questions, "As currently implemented, are existing California forest practice rules effective in preventing cumulative watershed impacts, including flooding?" and "What kind of measures might improve the effectiveness of forest practices rules for avoiding forestry-related cumulative watershed impacts