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256. Helgerson, O.T. 1990a. Effects of alternate types of microsite shade on survival of planted
Douglas-fir in southwest Oregon. New-Forests 3(4): 327-332.
Keywords: planting operations
tree/stand protection
tree/stand health
growth
Abstract: Five-yr survival of 2+0 bare root Douglas fir (Pseudotsuga menziesii) seedlings
was increased by 3 types of shading: cardboard shadecards placed S. or E. of seedlings; and
bottomless styrofoam cups inverted around seedling base, on 2 S.-facing sites. On the drier site,
seedlings survived well without shading (89% unshaded, 98% shaded), but on the wetter site,
where seedlings were more stressed, shading was more beneficial (62% unshaded, 89% shaded).
Shading did not affect growth. Seedlings grew more in 5 yr on the drier than the wetter site,
possibly because of better handling and planting practices, less browsing by deer, and better weed
control.
257. Helgerson, O.T. 1990b. Response of underplanted Douglas-fir to herbicide injection of
sclerophyll hardwoods in southwest Oregon. Western-Journal-of-Applied-Forestry 5(3): 86-89.
Keywords: nursery operations
release treatments
chemical release
stand conditions
tree physiology
tree/stand health
growth
Abstract: Low-value broadleaf sclerophyll forests in SW Oregon, typically composed of
tanoak (Lithocarpus densiflorus), Pacific madrone (Arbutus menziesii) and chinkapin
(Castanopsis chrysophylla), may be converted to commercially valuable Douglas fir (Pseudotsuga
menziesii) by underplanting. Results are given of studies of container-grown plug and nurserygrown
bareroot fir seedlings planted out in March 1983 on plots in which all broadleaf stems had
been previously (September 1981) injected with triclopyr amine. Although 60% broadleaf cover
was killed by injection, 7 years later ground cover was significantly greater on these treated plots
because of sprouting. Seedlings planted beneath treated broadleaf trees experienced greater
daytime, but less predawn, moisture stress; plugs survived better than bareroots; and survival of
seedlings on treated plots was not significantly better until 2 years after planting. Herbicide
injection also resulted in increased height, diameter and volume growth rates of Douglas fir
seedlings, and is recommended for the establishment of a conifer stand.
258. Helgerson, O.T., D.H. McNabb and S.D. Hobbs. 1991. Survival and growth of Douglas-fir
seedlings after prescribed burning of a brushfield in southwest Oregon. Western-Journal-of-
Applied-Forestry 6(3): 55-59.
Keywords: site preparation
prescribed fire
tree/stand health
growth