Treesearch

Cone, acorn, and berry crops of ponderosa pine (Pinus ponderosa Dougl. ex Laws. var. ponderosa), sugar pine (Pinus lambertiana Dougl.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), California white fir (Abies concolor var. lowiana (Gord.) Lemm.), incense-cedar (Libocedrus decurrens Torr.), California black oak (Quercus kelloggii Newb.), tan oak (Lithocarpus densiflorus (Hook. & Arn.) Rehd.), and Pacific madrone (Arbutus menziesii Pursh) were evaluated over a 24-year period (1958-1981) from an area in northern California by an easy to use visual crop rating system. Seed-trap data,...

In a ponderosa pine (Pinus ponderosaLaws.) forest near Flagstaff, AZ, USA, there was a striking pattern in forest characteristics, consisting of substands of old-growth trees (28–120 cm diameter at breast height (dbh) and 200–500 years old) and of saplings (1.5–10 cm dbh and 60–70 years old) in a matrix of pole-sized trees (10–28 cm dbh and 60–100 years old). Tree size and forest floor mass decreased from old-growth to pole to sapling substands, but soluble N (as KCl extractable inorganic N) in the mineral soil did not vary substantially among substands before prescribed burning. Prescribed...

With effective planning and management, urban trees and forests will provide a wide range of important benefits to urbanites. These include a more pleasant, healthful, and comfortable environment to live, work, and play in, savings in the costs of providing a wide range of urban services, and substantial improvements in individual and community wellbeing. Urban forestry plans should begin with consideration of the contribution that trees and forests can make to people's needs. Planning and management efforts should focus on how the forest can best meet those needs. Past planning and...

Urban greenspace provides many environmental and social services that contribute to the quality of life in cities. Economic approaches used to estimate value of greenspace services include travel cost, willingness to pay, hedonic pricing and tree valuation. These methods have limited utility for policy-makers, planners, and managers because the underlying values they estimate only indirectly reflect the flow of multiple benefits and costs. A greenspace accounting approach to partially address this deficiency is described using benefit-cost analysis for a proposed tree-planting project in...

Wildland fires that grow out of the initial attack phase are responsible for most of the damage and burned area. We model the allocation of fire suppression resources (ground crews, engines, bulldozers, and airdrops) to these large fires. The fireline at a given future time is partitioned into homogeneous segments on the basis of fuel type, available resources, risk, and other factors. Each is assigned a utility value corresponding to the importance of holding the segment. For a given resource allocation, the probability of holding the segment is modeled in terms of the (random) width of...

Seedlings of ponderosa pine (Pinus ponderosa Laws.) were grown for three years under three atmospheric ozone concentrations- clean air (CF), ambient ozone (NF), and 1-5 times ambient ozone (NF150) - at a moderatelypolluted site in the Sierra Nevada, under either well-watered or drought-stressed conditions. When the trees were 5 years old, photosynthetic capacities of 2-year-old, 1-year-old, and current-year needles were measured during August and September of the 3rd season of exposure. Current-year needles of NF150 trees had higher photosynthetic capacity than NF and CF trees during late...

This report is based an the Final Repart submitted on May 8, 1992 by the Technical Assessment Team to the interagency Steering Committee for the California Spotted Owl Assessment. The 13 chapters cover the assessment of the current status of the California spotted owl, its biology and habitat use, and forests where the subspecies occurs in the Sierra Nevada and southern California. The report suggests the direction of future inventories and research, identifies projected trends in habitat, and offers guidelines and recommendation for management of the California spotted owl.