Treesearch

Abstract - The effects of road building and selective tractor harvesting on storm peak flows and storm volumes were assessed for a small (424 hectare) coastal watershed in Northern California. Two watersheds, the North and South Fork of Caspar Creek were calibrated from 1962 to 1967 while no treatments took place. Roads were then built on the South Fork, and the two watersheds were monitored until 1971. Between 1971 and 1973 the South Fork was selectively tractor logged, removing 60 percent of the timber volume. The storm flows were monitored until 1976. Only the very small (566 l/s or...

The ""Selection At List Time"" (SALT) scheme controls sampling of concentration for estimating total suspended sediment yield. The probability of taking a sample is proportional to its estimated contribution to total suspended sediment discharge. This procedure gives unbiased estimates of total suspended sediment yield and the variance of the estimate while automatically emphasizing sampling at higher flows. When applied to real data with known yield, the SALT method underestimated total suspended sediment yield by less than 1%, whereas estimates by the flow duration sediment rating curve...

Abstract - Hydrograph lag time was analyzed to determine changes after road construction and after selective, tractor-yarded logging in a Caspar Creek watershed, Mendocino County, California. The paired watershed technique was used. Hydrograph lag time for each storm was the time separation between the midpoint of precipitation and the time coordinate of the runoff centroid. No significant change in lag time was detected after road construction. After logging, the lag time generally increased for small, early fall storms and decreased for larger storms. To determine whether the change...

Reported here are the results of studies on the unusually abrupt genetic transition that occurs in several traits in continuous bishop pine stands of northern Sonoma County, California. The genetic nature of this anomalous cline was investigated using allozyme, common garden, crossability, and controlled-soil analyses. Data from these analyses allowed a preliminary interpretation on the evolutionary relationships of the pines of this region. Initially, seeds were collected from 78 green foliaged trees in 8 stands south of the transition at Sea Ranch, from 27 blue, green or intermediate...

A three-dimensional diagnostic wind model for use in complex terrain has been combined with a three-dimensional trajectory and puff air quality model. The wind model utilizes a terrain following coordinate system and conserves both mass and momentum. The wind model provides the winds required by the predictive trajectory and puff dispersion model. Both the wind model and the dispersion models were compared with more complicated models and with wind and tracer gas data from the 1980 ASCOT experiment. Comparison of the wind model with Yamada's three-dimensional primitive equation solution...

Estimating rate of fire spread is a key element in planning for effective fire control. Land managers use the Rothermel spread model, but the model assumptions are violated when fuel, weather, and topography are nonuniform. This paper compares three averaging techniques--arithmetic mean of spread rates, spread based on mean fuel conditions, and harmonic mean of spread rates--used to estimate the effective rate-of-spread in heterogeneous environments. For particular ranges of the independent variables of the spread model, there is a well-defined ordering of the averages-a consequence of the...

Lodgepole and jack pines (Pinus contorta Dougl. ex. Loud, and Pinus banksiana Lamb.), components of the North American boreal forest, have pioneering roles after major disturbances such as fire or glaciation. These species are closely related and hybridize in western Canada, but their fossil records and contemporary variation patterns suggest they had completely different late Quaternary histories. Several taxonomically recognized geographic races of lodgepole pine apparently survived the last glaciation without drastic modification, the northern races either persisting in far-northern...

In recent years the term stem unit (SU) has increasingly supplanted internode in the literature of conifer shoot growth, especially since the adoption of SU in a collection of papers titled "Tree Physiology and Yield Improvement" (Cannell and Last 1976). In standard botanical terminology, a node is the point on a stem where one or more lateral appendages (foliage or scale leaves) are attached, and an internode is the portion of stem between two successive nodes. The original meaning of SU was more inclusive than internode, and the current practice of using SU and internode interchangeably...

A nonrandom sample of 90 arsonists in California and New York was interviewed for the California Department of Forestry from 1977 to 1979. About two-thirds of them were in prison for arson, and the others were in mental hospitals. The 90 interviewees were mostly unmarried males ranging in age from 17 to 51 years. Survey results show that those who set their first arson fire at a young age tended to set many fires, and had more arson convictions and repeated visits to mental hospitals than those who set their first fire at an older age.

Tests to rehabilitate gravel areas in high value recreation sites were carried out by transplanting short-hair sedge (Carex exserta) plugs. The plugs were 1.9 cm (0.75 inch) and 5.1 cm (2.0 inches) in diameter, 10 cm (4.0 inches) deep, and were transplanted in September 1981, with and without papier-mache pots. The test site was Siberian Outpost, in Sequoia National Park, California. Treatments were randomized in 40 quadrat pairs; one quadrat in each pair was fertilized. Results after 1 year showed that the most promising treatment was to transplant large diameter sod plugs unpotted and...