IntensIve sIlvIculture - Forest Science Labs - Research Network ...

elease treatments
yield
economics
143
Abstract: Models indicated that the yield and net present value (NPV) of young
Pseudotsuga menziesii stands in Oregon varied with site index and planting density. Effects of
hardwood competition in 20-year-old plantations were predicted using the Regional Vegetation
Management Model (RVMM). A stand table so produced was used for developing ORGANON,
which simulated silvicultural treatments and growth for 40-60 years. Output from this was used to
evaluate the economic consequences of hardwood competition using ORGECON. It was found
that the least impact was observed at low site index with high planting density. Modifications to
the models are suggested.
323. Knowe, S.A., B.D. Carrier and A. Dobkowski. 1995. Effects of bigleaf maple sprout clumps on
diameter and height growth of Douglas-fir. Western-Journal-of-Applied-Forestry 10(1): 5-11.
Keywords: release treatments
growth
Abstract: Diameter and height growth of 7- to 11-yr-old Douglas fir (Pseudotsuga
menziesii) were examined in relation to bigleaf maple (Acer macrophyllum) competition. Growth
models were developed for plantations in Oregon and Washington by joining a distance
dependent model with a model that excluded competition effects. The fitted equations were based
on Douglas fir size at plantation age 7 yr and distance from the stump and crown diameter of the
bigleaf maple clump. The model suggests that bigleaf maple clumps between 5.7 and 14.6 m from
planted Douglas firs reduce the latter's d.b.h. and height growth, and that this reduction becomes
greater with increasing size of the clump. A procedure is suggested to use the models to guide
vegetation management prescriptions on sites with bigleaf maple sprout clumps.
324. Knowe, S.A., T.B. Harrington and R.G. Shula. 1992. Incorporating the effects of interspecific
competition and vegetation management treatments in diameter distribution models for Douglasfir
saplings. Canadian-Journal-of-Forest-Research 22(9): 1255-1262.
Keywords: release treatments
manual release
chemical release
growth
tree morphology
Abstract: A parameter recovery procedure for the Weibull distribution function, based on
diameter percentiles, was modified to incorporate the effects of competing vegetation in young
Douglas fir (Pseudotsuga menziesii var. menziesii) plantations. The procedure was tested using
data from sites in the Coast Ranges of Oregon and Washington and in the Siskiyou Mountains of
SW Oregon. The Coast Ranges study was conducted in 2- to 3-yr-old plantations needing release
from woody shrub (mainly Rubus spectabilis and R. parviflorus) and broadleaved tree (Alnus
rubra and Acer macrophyllum) competition. Release treatments were an untreated control,
manual cutting, triclopyr ester applied aerially, glyphosate applied aerially, and a total vegetation
control treatment consisting of annual broadcast applications of hexazinone and spot treatments
of glyphosate and triclopyr. The Siskiyou Mountains study was conducted in 1- to 2-yr-old
plantations on sites covered by tanoak (Lithocarpus densiflorus). Tanoak sprout clumps were left
unthinned or were thinned to 50, 25 and 0% of the pretreatment cover. Four percentiles (0, 25th,