Treesearch

Abstract--An experimental and analytical study of heat and mass transfer in wooden dowels during a simulated fire is presented in this paper. The goal of this study is to understand the processes of heat and mass transfer in wood during wildland fires. A mathematical model is developed to describe the processes of heating, drying and pyrolysis of wood until ignition occurs. The governing equations of the model consist of a set of mass conservation equations for each species present (wood, water, air and released hydrocarbons), a momentum equation (Darcy's Law), and an overall energy...

El presente manual es una recopilación de métodos de campo para la determinación de índices de abundancia y datos demográficos de poblaciones de aves terrestres en una amplia variedad de hábitats. Está dirigido a biólogos, técnicos de campo, e investigadores de cualquier parte del Continente Americano. Los métodos descritos incluyen cuatro tipos de censos utilizados en la estimación de índices de abundancia y tendencias poblacionales, así como técnicas de captura con redes de niebla y búsqueda de nidos para la determinación de parámetros demográficos. Se presentan además otros métodos que...

The reintroduction of any species is inherently complex. For endangered species, the complexity is exacerbated by a shortage of sound policies, effective models, and strong scientific underpinnings.

A virulent race of blister rust capable of neutralizing major gene resistance (MGR) in sugar pine made its first appearance nearly two decades ago at a test plantation of resistant sugar pines near Happy Camp, in northern California. Until this year (1996), it had not been found outside the very close neighborhood of this site. Its discovery last summer at Mountain Home Demonstration State Forest (see Adams, preceding paper) was thus alarming, because of the implications this held for federal, State, and industry selection programs based on deploying MGR in commercial plantations. Mountain...

To assess the various ways organizations and people come together to manage Sierran ecosystems, SNEP conducted four case studies to examine the efficacy of different institutional arrangements: The Mammoth-June case study examines how a single national forest is attempting to implement the new Forest Service policy for ecosystem analysis. The Lake Tahoe study investigates a set of institutional arrangements in which agencies and the public have worked jointly for over thirty years to restore and maintain the health of a watershed-lake ecosystem being threatened by urbanization. The study...

A contingent valuation methodology was applied to old-growth forests and critical habitat units for the Northern Spotted Owl in Oregon to estimate the economic value to the public in knowing that rare and unique ecosystems will be protected from fire for current and future generations. Generalizing to the whole state, the total annual willingness-to-pay of Oregon residents ranges from $49.6 to $99 million. In terms of old-growth forests protected from fire, the value is $28 per acre.

On a medium site in northern California, a tanoak-mixed shrub community was given several treatments (manual release two and three times, a combination chainsaw and cut surface herbicide treatment, two foliar herbicides, and a tank mix of the two herbicides) to study its development in both a natural (control) and treated condition. The herbicides were 2,4-D, Garlon 3A, and Garlon 4, each applied two times. Survival of planted Douglas-fir seedlings was recorded for 11 years and growth was quantified for 9 years after the last treatment application. In addition to Douglas-fir, data are...

Managers of National Forests are faced with many challenges related to the growing use of mountain bikes. To determine the issues and management actions associated with this growth, USDA Forest Service managers from across the United States were surveyed. Managers from at least two National Forests from every Region (except Alaska) reported annual use of trails by 10,000 or more mountain bike riders. On the basis of this use, managers reported concerns and impacts related to the natural resources (degradation of trails, wilderness), social institutions (safety, education), and social...

A 3-year-old Jeffrey pine (Pinus jeffreyi Grev. & Balf.) plantation in northern California was released by grazing with sheep for 5 years, manual grubbing for 3 years, and applying a herbicide 1 year. These treatments plus an untreated control provided an opportunity to evaluate density and developmental trends for the pine, shrub, and grass components of the plant community during 1986-1994. Creating a near free-to-grow condition by applying Velpar herbicide modified the plant community by controlling the shrubs, reduced cheatgrass in the second and third years, and caused mean pine...

The equations presented predict crown area for 13 species of trees and shrubs which may be found growing in competition with commercial conifers during early stages of stand development. The equations express crown area as a function of basal area and height. Parameters were estimated for each species individually using weighted nonlinear least square regression.