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

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increased with time. The age-adjusted competition index accounted for 11% of the variation in
height and 19% of the variation in stem diameter. Douglas fir stem diameter was more sensitive
to neighbouring woody plants than was height.
640. Wagner, R.G. and M.W. Rogozynski. 1994. Controlling sprout clumps of bigleaf maple with
herbicides and manual cutting. Western Journal of Applied Forestry 9:118-124.
Keywords: release treatments
chemical release
manual release
stand conditions
Abstract: Trials were conducted in 5 young Douglas fir (Pseudotsuga menziesii)
plantations for controlling bigleaf maple (Acer macrophyllum) clumps. Herbicides tested were
glyphosate (Roundup), imazapyr (Arsenal), metsulfuron methyl (Escort), triclopyr amine (Garlon
3A), triclopyr ester (Garlon 4), and 2,4-DP [dichlorprop] + 2,4-D (Weedone 170). Four methods
of herbicide application (basal spray, thinline, foliage spray, and cut-surface) and 3 treatment
timings (early foliar, late foliar, and dormant periods) were tested. Manual cutting alone was also
evaluated at each of the treatment timings. Imazapyr foliage sprays, triclopyr ester thinline,
dormant 3% triclopyr ester basal spray, late-foliar 2,4-DP + 2,4-D basal spray, and manual
cutting with triclopyr amine cut-surface application provided the best control among the
treatments tested over the 3 yr of study. Imazapyr foliage sprays provided the best long-term
control by killing most treated clumps. Triclopyr ester thinline treatments provided the most
consistent and effective results among the basal applications. Stump applications of triclopyr
amine were more effective than manual cutting alone or manual cutting with glyphosate cutsurface
application.
641. Walker, R.B., S.P. Gessel and R.E. Miller. 1994. Greenhouse and laboratory evaluation of two
soils derived from volcanic ash. Northwest-Science 68(4): 250-258.
Keywords: fertilization
growth
tree/stand health
carbon allocation
tree morphology
tree physiology
Abstract: This study assessed the mineral nutrient status of two soils derived from volcanic
ash in SW Oregon. The study was initiated because conifers in some of the field plots on such
soils had failed to give an expected yield response to the application of nitrogen fertilizer. Soil pot
tests were carried out using both Romaine lettuce (Lactuca sativa) and Douglas fir (Pseudotsuga
menziesii) seedlings, with a wide range of fertilizer treatments. Heavy phosphorus fertilization
was necessary for satisfactory growth of lettuce, which also showed a 26% response to sulfur
addition. With Douglas fir, pot tests showed no response to nitrogen alone, but gave a statistically
significant response to phosphorus fertilization together with nitrogen (seedlings were nonmycorrhizal),
and some suppression of yield with sulfur additions. There was a favourable effect
of sulfur fertilization on foliar colour, and a chlorosis in younger foliage probably attributable to
iron deficiency. Most of the tissue analyses showed low concentrations of magnesium (