Treesearch

In this commentary I will be discussing the acquisition and transfer of scientific information. As I perceive it, those tasks are the principal business of all of us attending this symposium. I have come to the conclusion based on my review of Theme 3 papers, that many of us are not fulfilling our obligations as scientists as adequately as we ought to when we set about to acquire new information and report it to our peers

Seedlings of six full-sib families of loblolly pine were grown outdoors in clay pots for two growing seasons. Dark respiration of shoot and root and CO2 exchange of the shoot in the light were measured periodically over a temperature range bracketing ambient conditions. Both shoot and root showed different physiological responses as seasonal temperature changed, but differences among crosses were not apparent. Optimum temperatures for net photosynthesis shifted with seasonal temperatures from a high of nearly 25 C in midsummer to a low of 10 C in midwinter. Root respiration was higher at...

Five insect molt inhibitors (MI's) were mixed with artificial diet and fed to 3rd and 6th stage western spruce budworm (Choristoneura occidentalis) larvae and 2nd stage Douglas-fir tussock moth (Orgyia pseudotsugata) larvae. In general, tussock moth larvae were more susceptible that western spruce budworm larvae to these MI's SIR 6874 was by far the most toxic to 3rd and 6th stage western spruce budworm, and diflubenzuron the least toxic. TH 75331 and EL-494 both showed sustantial activity against this insect, while SIR 8514 was relatively less active but was still at least 3 times as...

This guide, based on a literature review and personal contacts, offers recommendations and standards for procedures in reducing losses of residences from wildfires. Possible solutions to the problem of fire protection are discussed in the broad areas of land-use planning and zoning, property development, structural design and construction, landscaping, accessories, occupant activities, and financial incentives. The problem of reducing fire losses in undeveloped areas is also discussed and solutions proposed. The guide is intended for homeowners, lawmakers, and members of the building,...

Three tree improvement programs were analyzed by break-even, cost-benefit technique: one for ponderosa pine in the Pacific Northwest, and two for Douglas-fir in the Pacific Northwest-one of low intensity and the other of high intensity. A return of 8 percent on investment appears feasible by using short rotations or by accompanying tree improvement with thinning. Interest rates, length of rotation, the inclusion of thinnings, and site index had greater effects on profitability than program design. Large breeding zones improved profitability, although they incur the biological risks of...

A disease of Jeffrey pines (Pinus jeffreyi Grev. and Balf.) at Lake Tahoe Basin, California, caused by Elytrodenna disease (Elytroderma deformans) was studied for 7 years after a severe outbreak ofthe fungus in 1971. Among 607 Jeffrey pines on six plots, about one-half were heavily infected and about one-half were moderately or lightly infected in 1971. No uninfected trees were observed. During the 7-year study, about one-half of the trees remained unchanged in vigor, disease intensity, or both, and about one-half decreased in vigor, became more heavily infected, or both. Of the original...

In a 1964-1967 study on the Challenge Experimental Forest, seedfall was evaluated in 2-, 5-, and 10-acre circular clearcuttings. During the 4 years, 10 seed crops, ranging from light to bumper, were produced by ponderosa pine. white fir, Douglas-fir, and incense cedar. Seedfall ranged from 76 to 40,691 sound seed per acre (188 to lOO,547/ha) for a single species in a given year. From 89 to 100 percent of each species' seed fell within an area 1½ times the height of the average dominant tree. Overall, seed distribution was highly variable.