Treesearch

Two races of bishop pine (Pinus muricata D. Don) meet in a narrow contact zone near sea level along the Sonoma County coast, northern California. The races previously were identified by foliar ("blue" in north, "green" in south), monoterpene, and allozyme differences. Disjunct stands of blue bishop pine were observed at higher elevations along a ridge south of the contact zone on patches of infertile pygmy-forest soils. Green bishop pine arew on fertile soils 0.5 km from the pygmy-forest parches. The frequency of trees with blue foliage in pygmy-forest stands was 0.73-0.86. One ridgetop...

Using starch gel electrophoresis of proteins, we examined variation at 36 genetic loci in nine species (eight genera) of Hawaiian honeycreepers (Class Aves; Family Fringillidae; Subfamily Drepanidinae). Two species of cardueline finches and two emberizids served as outgroup taxa. Twenty-three loci (64%) were either polymorphic within taxa and/or were fixed at alternative alleles among taxa. In seven of nine species, low levels of mean Hobs (0.015), percentage of polymorphic loci (4.16), and average number of alleles per polymorphic locus (2.03) may reflect population bottlenecks that...

Timber stands in western Washington are managed for many purposes. Such stands yield commodity and noncommodity outputs, such as recreation, wildlife, visual resources, or watershed benefits, and often from the same stands. Annosus root disease is widespread in many mixed conifer stands within the western hemlock, mountain hemlock, and Pacific silver fir zones west of the Cascades. In stands managed on commercial (commodity output) rotations, annosus root disease is not considered a major management concern. This is not true of stands managed principally for noncommodity outputs such as...

Actual loss from annosus root disease infections in hemlock stands is difficult to determine. As political trends move toward protecting old-growth timber, greater market demand will be placed on second growth western hemlock. These stands must be kept healthy for maximum productivity. The paper compares the following 70-year rotation timber management scenarios: The first has a single juvenile spacing entry and low infection. The second has early spacing plus a commercial thinning with considerable crop tree wounding and high infection. Operational guidelines are presented for management...

A historical perspective and description of recent studies on the use of borax to treat pine stumps against infection by Heterobasidion annosum in eastside pine stands of northeastern California are presented. The studies indicate that boraxing of pines in eastside pine stands is an effective means of preventing annosus infection. Data and observations suggest that the lower stump diameter limit for treating chain saw-cut pines with borax could be raised from the currently recommended 8 inches (20.3 cm) to about 16 inches (40.6 cm) with little or no risk of creating active annosus root...

Trees affected by the annosus root disease are easily windthrown or fall without visible symptoms that might warn forest recreation managers of impending failure. Some of the treeshave struck cabins or campsites, causing death or destroying vehicles and recreational facilities. To prevent loss of life or property, and to save as many trees as possible for landscaping purposes, the management option of creating a buffer zone by removing the first line of trees from around each infection center was selected. However, the selection of buffer zone cutting resulted in removing 249 trees or...

The Western Root Disease Model as it currently exists is described, and the assumptions that were made to adapt the model to simulate attack by Heterobasidion annosum in coniferous forests of south-central Oregon are defined. Some simulations produced by this adapted model are presented to stimulate provocative discussion, thought, and action. These simulations indicate that with no action, or with continued improper management, annosus root disease will severely reduce timber yields in affected stands of true fir. Coupled with other information, this exercise provides a framework from...

Associations between root diseases and bark beetles (Scolytidae) constitute some of the most serious pest complexes affecting forests in North America and elsewhere. The interactive functioning of these pests derives from the following relationships: 1) root diseases predispose trees to bark beetle infestation by lowering resistance, and perhaps increasing attractiveness, of trees to the attacking beetles; 2) bark beetles may be vectors of root disease fungi or may create infection courts for them.

Annosus root disease (ARD), is the major root disease of pines in the southeastern United States where severely affected trees exhibit growth loss. Assessing the potential damage of ARD is essential for making effective disease control and management decisions. A soil hazard rating system developed to identify potential for tree mortality is described. The Annosus Sampling Procedure accurately estimates the severity of ARD within a stand. The GY-ANNOSUS computer program estimates growth loss caused by ARD. ARD management strategies are discussed.

An evaluation of basal area increment was made in 1988 of six pine plantations located across the southeastern United States. These plantations had been thinned in 1969-1970 and stumps treated with borax to measure long-term efficacy of annosus root rot control. In the present study, no long-term growth effects were identified. There were neither negative growth effects of residual infection in surviving trees nor were there positive growth effects in trees which were released as a result of tree mortality. These results suggest that effects of inoculation and control treatments may have...