A study on the effects of light quality and periodicity on the germination of Douglas-fir seed and the growth of Douglas-fir seedlings was conducted. Interest was focused on responses that could be measured and observed without biochemical assay. It was found that .Douglas-fir seed,s would respond to red-light treatments by...
The Pacific Northwest (PNW) is an important region for winter wheat
production in the USA, where water deficits are often present at sowing and during
grain filling. Consequently, improving the genetic adaptation of wheat cultivars to
drought stress represents one of the main objectives in breeding programs. An
observed biochemical...
Thinning has the potential to increase structural diversity of managed forests for wildlife. During 1994-1996, I conducted experimental and observational studies using pitfall trapping to assess short-term and potential long-term effects of thinning on abundance and reproduction of forest-floor vertebrates in Douglas-fir (Pseudotsuga menzeisii) forests of the Oregon Coast Range....
One-year-old container-grown Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings were outplanted on north, east, south, and west aspects on steep, skeletal Xerochrepts in southwest Oregon. After 2 years, survival rates were highest on north and south aspects, but biomass production (dry weight) was greatest on the west aspect. Shadecards, used to...
Wood density is controlled to a large extent by the relative widths of earlywood and latewood in the stem, but the mechanisms controlling these amounts are poorly understood in coastal Douglas-fir. To understand the role of climatic factors, one hundred and thirty-six increment cores were collected and measured from the...
Foliage from Douglas-fir(var. glauca) seedlings grown under two light intensities was bioassayed to examine palatability to the
western spruce budworm (Choristoneura occidentalis Free.). Samples were collected in Fall, Winter and early Spring to
identify seasonal changes in host foliage, as evidenced by the response of spruce budworms. Fall collected foliage...
To understand the effect of human-induced stresses on forests, there is a need for a method to separate effects of imposed stress from effects of natural climate stress. I developed an approach to predict forest response to climate stress using as indicators stable carbon isotopes in tree foliage and growth-rings....