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Rate of population buildup of dwarf mistletoe, Arceuthobium abietinum Engelm. ex Munz., was slow in most small red firs and white firs 12 to 15 years after inoculation with the parasite. Where population buildup did occur, it remained clustered in the lower portions of tree crowns near inoculation sites. Maximum distance of vertical spread was 16 feet (4.8 m), after 15 years. The mean annual rate of vertical spread of the parasite in 12 to 15 years was 3 inches (7 cm) or less in test trees. No vertical spread occurred in some trees. Rate of vertical spread was much slower in all trees than...

A two-stage shelterwood cutting, at 12 trees per acre, with site preparation, enhanced seedfall, regeneration, and residual growth at the Challenge Experimental Forest, north central California. Shelterwood trees produced 9.2 times more seed than trees in the control. Ponderosa pine regeneration numbered about 3700 seedlings per acre (9139 per ha) and tolerant conifers 600 seedlings (1482 per ha) after 5 years. Hardwood seedlings and sprouts also were abundant. Basal area growth rates for all species in nearly all diameter classes were greater in the shelterwood than in the control. The...

Ponderosa pine seed trees, numbering 4, 8, and 12 per acre, were left standing for 9 years after harvest cutting on the Challenge Experimental Forest, Calif. Seedling heights were measured at ages 5, 9, and 14, and for all ages were poorest if within 20 feet of a seed tree. Seedlings 20 feet or less from a seed tree at the ages given lost the equivalent in years of height growth: 5(4.1); 9(6.8); 13(10.6). Seed-tree density greatly affected seedling height-the greater the density, the poorer the height growth. The inhibitory effect of the seed trees extended outward at least 40 feet, and...

Mass divergence influences on plume dispersion modify classic Gaussian calculations by as much as a factor of two in complex terrain. The Gaussian plume was derived in flux form to include this process. Authors' response to comments and criticism received following this publication: Author's response

The abundance, distribution, growth, and mortality of koa (Acacia koa Gray) seedlings after fires were monitored periodically on two burned areas on Oahu for 2.5 years. On one area, seedling density peaked at 95,300/ha 6 months after the fire; 21 months later it had declined to 18,500/ha. On the other area, peak seedling density occurred at 2 -months, with 20,400/ha; 26 months later, density had dropped to 7900/ha. Seedlings were not distributed uniformly over the burned areas but were concentrated near koa seed trees. Height growth for seedlings on one area averaged 2.6 cm/mo; on the...

The contact toxlaty of 100 insecticides to last stage larvae of Choristoneura occidentalis Freeman was tested by topical application in a 10-yr series of screening experiments. Pyrethroids were generally the most toxic group of chemicals tested. Compounds more toxic than the standard, mexacarbate, at LD90 were: bioethanomethrin, (+) cis-resmethrin, (+) trans-resmethrin, (+) cis-phenothrill. ENT 29l17 (5-benzyl-3-furylmethyl (IR,3S,E) 2,2-dimethyl-3- (2-oxo-3-tetrahydrothiophenylidenmethyl) cyclopropanecarboxylate), resmethrin, and NRDC 143 (3-phenoxybenzyl (±) -3- (2,2-dichlorovinyl-2,2-dim...

The abundance and distribution of Acacia koa regeneration after logging were studied on a 500-acre (202-ha) tract of koa forest heavily infested with Passiflora mollissima vines on the island of Hawaii. Koa seedling density was about three times greater in disturbed areas than in undisturbed ones. Most of the koa seedlings in the sample tha t grew in response to ground disturbance during logging were established. None of those found in undisturbed areas were established. Seedlings in disturbed areas tended to be clustered near koa seed trees, with twice as many growing within 50 feet (15.2...

Chaparral modification is undertaken for a variety of land-management purposes. To help land managers in selecting equipment and methods for such work, practitioners in county, State, and Federal modification projects were asked for evaluations of equipment and techniques they had used. This handbook describes the alternative techniques and equipment, provides information on operations, reports production rates and on-site costs, and explains the advantages and limitations of equipment used for brush crushing, compacting, chopping, and shredding and for grass seeding. Tools for hand...

Fuel moisture estimates generated by the National Fire-Danger Rating System procedure were compared with actual fuel moisture measurements determined from laboratory analysis. Meteorological data required for the NFDRS procedure were collected at two heights to assess the effect of temperature and humidity lapse rates. Standard measurements gave the best results, but use of a xeric hygrometer showed promise of giving reliable fuel moisture estimates by a simple linear regression.