1. 1987. Impact of intensive forestry practices on net stand
values in
Keywords: release treatments
fertilization thinning yieldeconomics
Abstract: Yield responses to major silvicultural treatments
(regeneration method, brushing and weeding, spacing and thinning and fertilizer
use) are analysed in relation to growth and yield theory, and their translation
into operational use of treatments to increase merchantable vol. is considered.
Data from coastal Douglas fir (Pseudotsuga menziesii), western hemlock (Tsuga
heterophylla) and western hemlock/Abies amabilis stands and interior white
spruce (Picea glauca), lodgepole pine (Pinus contorta) and wet belt Douglas fir
stands are used to quantify the net present value of treatments in terms of
improvement in net stand values and merchantable vol. Potentially viable
treatment options are identified for each stand type present.
2. Belz, D. and T.E. Nishimura. 1989.
Effects of imazapyr, 2,4-D and metsulfuron methyl on
conifer tolerance. Proceedings-of-the-Western-Society-of-Weed-Science (Vol.
42): 98-104.
Keywords: site preparation
chemical preparation
release treatments
chemical release
tree/stand health
Abstract: Imazapyr
at 0.25-1.0 lb/acre alone or 0.5 lb/acre in combination with 2,4-D 2 lb/acre or metsulfuron 0.3 lb/acre was evaluated for
effect on growth and injury to Pseudotsuga menziesii, Pinus ponderosa, Tsuga
heterophylla and Abies amabilis seedlings in the
3. Brandeis, T.J., M. Newton and E.C.
Cole. 2001. Underplanted conifer seedling survival and growth in thinned
Douglas-fir stands. Canadian-Journal-of-Forest-Research 31(2): 302-312.
Keywords: planting operations
thinning
commercial thinning
site preparation
chemical preparation
release treatments
chemical release
growth
tree/stand health
regeneration
Abstract: In a
multilevel study conducted at the Oregon State University's McDonald-Dunn
Research Forest, Oregon, USA, to determine limits to underplanted conifer
seedling growth, Douglas-fir (Pseudotsuga menziesii), grand fir (Abies
grandis), western redcedar (Thuja plicata) and western hemlock (Tsuga
heterophylla) seedlings were planted in January 1993 beneath second-growth
Douglas-fir stands that had been thinned in 1992 to basal areas ranging from 16
to 31 m2/ha. Understorey vegetation was treated with a broadcast herbicide
(glyphosate + imazapyr) application prior to thinning, a directed release
herbicide (glyphosate, plus triclopyr for tolerant woody stems) application 2
years later, or no treatment beyond harvest disturbance. Residual overstorey
density was negatively correlated with percent survival for all four species.
Broadcast herbicide application improved survival of grand fir and western
hemlock. Western redcedar, grand fir and western hemlock stem volumes were
inversely related to overstorey tree density and this effect increased over
time. There was a strong indication that this was also the case for
Douglas-fir. Reduction of competing understorey vegetation resulted in larger
fourth-year stem volumes in grand fir and western hemlock.
4. Brandeis, T.J., M. Newton and E.C.
Cole. 2002. Biotic injuries on conifer seedlings planted in forest understory
environments. New Forests 24:1-14.
Keywords: planting operations
site preparation
chemical preparation
release treatments
chemical release
thinning
tree/stand protection
growth
tree/stand health
Abstract: The
effects of partial overstorey retention, understorey vegetation management, and
protective Vexar(R) tubing on the frequency and severity of biotic injuries in
a two-storied stand underplanted with western redcedar (Thuja plicata),
Douglas-fir (Pseudotsuga menziesii), grand fir (Abies grandis), and western
hemlock (Tsuga heterophylla) were investigated. The most prevalent source of
damage was browsing by black-tailed deer (Odocoileus hemionis columbiana); deer
browsed over 74% of Douglas-fir and over 36% of western redcedar seedlings one
or more times over the four years of this study. Neither the spatial pattern of
thinning (even or uneven) nor the density of residual overstorey affected
browsing frequency. Spraying subplots may have slightly increased browsing
frequency, but the resulting reduction of the adjacent understorey vegetation
increased the volume of all seedlings by 13%, whether or not they were browsed.
Vexar(R) tubing did not substantially affect seedling survival, browsing damage
frequency, or fourth-year volume. Greater levels of overstorey retention
reduced frequency of second flushing. Chafing by deer and girdling by rodents
and other small mammals began once seedlings surpassed 1 m in height.
Essentially all grand fir seedlings exhibited a foliar fungus infection.
5. Busse, M.D., G.O. Fiddler and A.W.
Ratcliff. 2004. Ectomycorrhizal formation in herbicide-treated soils of
differing clay and organic matter content. Water, Air, and Soil Pollution
152:23-34.
Keywords: release treatments
chemical release
growth
tree morphology
tree/stand health
soil properties
mycorrhizal response
Abstract: Herbicides
are commonly used on private timberlands in the western
6. Cole, E.C. and M. Newton. 1987.
Fifth-year response of Douglas-fir to crowding and nonconiferous competition.
Canadian-Journal-of-Forest-Research 17(2): 181-186.
Keywords: release treatments
chemical release
growth
tree morphology
Abstract: Measurements
were made in autumn 1982 in 5-yr-old plantations with trees spaced 17-123 cm
apart, alone or with grass or red alder (Alnus rubra) on 3 site types in the
7. Cole, E.C. and M. Newton. 1989a.
Height growth response in Christmas trees to sulfometuron and other herbicides.
Proceedings-of-the-Western-Society-of-Weed-Science (Vol. 42): 129-135.
Keywords: release treatments
chemical release
growth
tree/stand health
stand conditions
Abstract: Abies
procera, A. grandis and Pseudotsuga menziesii cv. Menziesii were evaluated for
tolerance to sulfometuron (0.05-0.21 kg/ha), atrazine (4.5 kg/ha) and
hexazinone (2.2 kg/ha). Herbicides were applied pre-budbreak and sulfometuron
was also applied post-budbreak. Weeds were suppressed equally effectively by
all rates and herbicides pre-em. Low rates of sulfometuron were less effective
post-em. There was no significant damage to A. procera seedlings, although the
highest rate of sulfometuron slowed growth significantly. A. grandis was not
affected by any treatment. All treatments caused injury to 1-year-old P.
menziesii, primarily needle chlorosis and slight stunting. Growth was best in
atrazine-treated plots. For 3-year-old P. menziesii, injury was not significant
but high rates of sulfometuron caused cosmetic damage. Best growth was observed
with hexazinone and worst with sulfometuron. Post-budbreak applications and
high rates of sulfometuron reduced growth more than pre-budbreak application
and low rates.
8. Cole, E.C. and M. Newton. 1989b. Seasonal efficacy comparison of two glyphosate formulations.
Proceedings-of-the-Western-Society-of-Weed-Science (Vol. 42): 136-142.
Keywords: release treatments
chemical release
tree/stand health
stand conditions
Abstract:
Glyphosate formulations with 13% (Roundup) and without (Accord) surfactant were
compared at 0.84 and 1.68 kg/ha, applied June-Oct. against Alnus rubra, Rubus
spectabilis, R. parviflorus, R. ursinus and Pteridium
aquilinum in a Pseudotsuga menziesii cv. menziesii plantation. No differences
in efficacy between the two formulations against any species were noted. All
species were controlled better by high rates of herbicide. R. spectabilis and
R. parviflorus were controlled <less or =>100%, although July
applications were least effective. A. rubra was reduced <less or =>80%
and early application gave best control. Rates of application had less effect
on Pteridium aquilinum control (<less or =>98%), and Oct. applications
were least effective. Damage to Pseudotsuga menziesii was worst with June
applications and decreased through the year. Oct. treatment caused negligible
damage.
9. Cole, E.C., M. Newton and D.E.
White. 1986. Response of northwestern hardwoods, shrubs, and Douglas-fir to
Arsenal and Escort. Proceedings-of-the-Western-Society-of-Weed-Science
(Vol.39): 93-101.
Keywords: release treatments
chemical release
tree/stand health
stand conditions
Abstract: Arsenal
(imazapyr) and DPX-T6376 (metsulfuron) were evaluated for scrub control in
Pseudotsuga menziesii plantations at 3 sites in
10. Cole, E.C., M. Newton and D.E.
White. 1988. Efficacy of imazapyr and metsulfuron methyl for site preparation
and conifer release in the
Keywords: release treatments
chemical release
tree/stand health
stand conditions
Abstract: Imazapyr
(Arsenal) and metsulfuron methyl (Escort) were tested at 3 rates for
controlling shrubs in young Douglas fir (Pseudotsuga menziesii) plantations on
3 sites in the
11. DeBell, D.S. and T.C.
Turpin. 1989. Control
of red alder by cutting. Pacific-Northwest-Research-Station,-USDA-
Keywords: release treatments
manual release
stand conditions
Abstract: Effects
of tree age, month of cutting, and height and angle of the cut on sprouting of
red alder (Alnus rubra) stumps were evaluated in a study designed to develop an
effective method for controlling red alder in Douglas fir (Pseudotsuga
menziesii) plantations in the Oregon Coast Range.
12. Dimock, E.J., II and E.B.
Collard. 1981. Postplanting sprays of dalapon and atrazine to aid conifer
establishment. Pacific-Northwest-Forest-and-Range-Experiment-Station,-USDA-
Keywords: release treatments
chemical release
growth
tree/stand health
stand conditions
Abstract: A
mixture of dalapon and atrazine at 8 and 4 lb/acre, respectively, or dalapon or
atrazine alone were applied to control perennial grasses and forbs competing
with newly planted seedlings of ponderosa pine and Douglas fir. In 4 studies in
13. Figueroa, P.F. 1989. Bigleaf
maple control: triclopyr thin-line and spot-foliar application treatments using
imazapyr, metsulfuron, and glyphosate.
Proceedings-of-the-Western-Society-of-Weed-Science (Vol. 42): 104-119.
Keywords: release treatments
chemical release
stand conditions
economics
Abstract: Field
trials were conducted to compare the efficacies of March applications of
triclopyr thin-line +or- 1 kg/ha Mor-act or 2,4-D
(1:1) with June spot-foliar applications of 0.6 or 1.1 kg/ha imazapyr, 0.170
kg/ha metsulfuron and 6.7 kg/ha glyphosate to control Acer macrophyllum in a
Pseudotsuga menziesii plantation. All thin-line treatments gave 80% control 2
years later; complete sanding was hindered by stems growing along the ground.
Dilution did not affect control. Spot-application success depended on degree of
crown coverage. metsulfuron and glyphosate were not
effective, but imazapyr control reached 60-70% 2 years after treatment. Only
triclopyr and full coverage imazapyr suppressed A. macrophyllum growth to below
the height of P. menziesii. Crown volume was held to pre-treatment levels with
metsulfuron and glyphosate but decreased with imazapyr. The two treatment
methods tested are potentially cost-effective; triclopyr costs are higher but
spot-application carries higher labour costs. Application rates of 2 ml
triclopyr/ Msuperscript 2 crown area will give 100% control if all stems are
banded; with delivery rates of 59 ml/clump a 45% solution can be used.
14. Figueroa, P.F. 1991. Ground
applied herbicide methods for red alder control: herbicide efficacy, labor
costs, and treatment method efficiency. In
Proceedings-of-the-Western-Society-of-Weed-Science,12-14-March-1991.
pp. 44: 53-68.
Keywords: release treatments
chemical release
economics
stand conditions
Abstract: A study
was conducted to develop the cost estimates for ground-applied manual control
methods in variable density red alder [Alnus rubra] stands and to evaluate the
efficacy of the various herbicide formulations for each system. Field trials
were initiated in 3 Douglas fir [Pseudotsuga menziesii] plantations located on
Weyerhaeuser Company land located in
15. Figueroa, P.F. 1993. Efficacy and
cost of ground-applied herbicide methods for red alder control. Down to Earth
48(1): 6-10.
Keywords: release treatments
chemical release
stand conditions
growth
tree/stand health
Abstract: The
effects on red alder [Alnus rubra] mortality, diam. at breast height and
height, and any phytotoxic effects to Douglas fir [Pseudotsuga menziesii] of
Garlon 4 (triclopyr) at 4 lb/gallon and Chopper EC (imazapyr) at 2 lb, applied
by stream line, thin line and low vol. treatments, and of Garlon 3A (triclopyr)
at 3 lb, Roundup (glyphosate) at 3 lb and Arsenal (imazapyr) at 4 lb applied by
cut stump treatment were evaluated in streamside buffer zones in two 6-year-old
P. menziesii plantations in SW Washington. All treatments resulted in good
control of A. rubra, but the most cost-effective control was achieved by the
stream line application of Garlon 4, followed by low vol. basal or thin line
treatments of Garlon 4 and cut stump treatment with 50% Garlon 3, 45% Roundup
and 10% Arsenal. Negligible P. menziesii damage was caused by cut stump
treatments, but damage occurred with basal-bark treatments although Garlon 4
generally caused less injury than Chopper EC.
16. Figueroa, P.F. and V.F.
Carrithers. 1993. Bigleaf maple control: thinline basal applications using
triclopyr and triclopyr plus picloram. In Proceedings-of-the-Western-Society-of-Weed-Science,
9-11-March-1993. pp. 46: 24-30.
Keywords: release treatments
chemical release
stand conditions
economics
Abstract: A field
trial was conducted at Mt. St. Helens Tree Farm, Cowlitz county, Washington, in
1988-91 to determine the min. threshold level of herbicide needed to control
bigleaf maple [Acer macrophyllum] stump sprouts in Douglas fir [Pseudotsuga
menziesii]. Garlon (triclopyr) at 0.24-3 lb/gal was applied on
17. Figueroa, P.F., R.C. Heald and
S.R. Radosevich. 1990. Sensitivity of actively growing Douglas-fir to selected
herbicide formulations. Proceedings-of-the-Western-Society-of-Weed-Science 43:
45-52.
Keywords: release treatments
chemical release
growth
tree/stand health
Abstract: The
results of field studies at 2 sites in Washington and California indicated that
aerial spraying of 2,4-D at 4 lb/acre, triclopyr ester
at 4 lb/acre or 2,4-D + triclopyr ester at 1.2 lb/acre + 0.5 lb/acre to control
red alder [Alnus rubra] led to a significant reduction in Douglas fir
[Pseudotsuga menziesii] growth and survival if applied during periods of active
conifer growth. Herbicides applied singly at high rates caused significantly
more mortality than the herbicides in combination. At both sites, trees had not
fully recovered 5 and 6 years after treatment; damaged trees were at least 1
year behind untreated trees in growth.
18. Fischer, V.F. and V.F.
Carrithers. 1992. Tolerance of one and two year old douglas-fir seedlings to
triclopyr applications. In
Proceedings-of-the-Western-Society-of-Weed-Science, 10-12-March-1992.
Keywords: release treatments
chemical release
tree/stand health
Abstract: In
field trials conducted near
19.
Keywords: release treatments
chemical release
manual release
growth
soil properties
Abstract: Harsh environments
on many harvested sites in
20. Gourley, M., M. Vomocil and M.
Newton.
Keywords: release treatments
chemical release
tree/stand protection
growth
tree/stand health
Abstract: In
January and February 1981, three-year-old bare-root Douglas fir (Pseudotsuga
menziesii) transplants were established in four clear-felled locations in the
21. Haight, R.G. 1993a. The economics of Douglas-fir and red alder management with
stochastic price trends. Canadian-Journal-of-Forest-Research 23(8):
1695-1703.
Keywords: planting operations
site preparation
prescribed fire
release treatments
chemical release
thinning
precommercial thinning
commercial thinning
tree/stand protection
economics
Abstract: A
financial analysis of Douglas fir (Pseudotsuga menziesii) and red alder (Alnus rubra)
management was conducted using yield projections from the Stand Projection
Simulator for the
22. Haight, R.G. 1993b. Technology change and the economics of silvicultural investment.
Rocky-Mountain-Forest-and-Range-Experiment-Station,-USDA-
Keywords: planting operations
site preparation
prescribed fire
release treatments
chemical release
tree/stand protection
thinning
commercial thinning
precommercial thinning
yield
economics
Abstract: Financial
analyses of intensive and low-cost reforestation options are conducted for
loblolly pine (Pinus contorta) stands with broadleaved competition in the
Southern USA, and Douglas fir with red alder (Pseudotsuga menziesii with Alnus
rubra) in the Pacific Northwest. Results show that the expected present values
(EPVs) of low-cost options that result in mixtures of conifers and broadleaves
are superior in some situations to the EPVs of the intensive options.
23. Harrington, T.B. and J.C.
Tappeiner, II. 1997. Growth responses of young Douglas-fir and tanoak 11 years
after various levels of hardwood removal and understory suppression in southwestern
Keywords: release treatments
manual release
growth
tree/stand health
Abstract:
24. Harrington, T.B., J.C. Tappeiner,
II and T.F. Hughes. 1991. Predicting average growth and size distributions of
Douglas-fir saplings competing with sprout clumps of tanoak or Pacific madrone.
New-Forests 5(2): 109-130.
Keywords: release treatments
manual release
growth
stand conditions
Abstract: Average
growth and size distributions of 3- to 6-year-old (in 1983) Douglas fir
(Pseudotsuga menziesii) saplings in three plantations in SW Oregon were studied
for 7 years (1983-1989) after thinning of associated sprout clumps of tanoak
(Lithocarpus densiflorus) or Pacific madrone (Arbutus menziesii); in some cases
shrubs and herbs were also suppressed. Biologically based nonlinear equations
explained 66, 90, and 53% of variation in average annual increment of Douglas
fir height, diameter-squared, and crown cover, respectively. Equations for
annual increment of crown cover of broadleaved and understorey vegetation
explained only 10 to 12% of the variation, because these parameters exhibited a
high degree of variability. Model simulations demonstrated that, for the same
initial levels of cover, tanoak had faster rates of crown cover growth than
madrone and also caused greater limitations in Douglas fir growth. Suppression
of shrubs and herbs increased growth of Douglas fir only when broadleaved
species were absent. Weibull functions adequately described size distributions
for Douglas fir in 92% of individual-tree data sets. Regression functions of
broadleaved crown cover and average Douglas fir size explained 51, 93, and 24%
of variation in the Weibull A, B, and C parameters, respectively. Model
simulations with predicted Weibull parameters demonstrated that broadleaved
competition caused a positive skewing in size distributions for height and stem
diameter of Douglas fir.
25. Harrington, T.B., R.G. Wagner,
S.R. Radosevich and J.D. Walstad. 1995. Interspecific competition and herbicide
injury influence 10-year responses of coastal Douglas-fir and associated
vegetation to release treatments. Forest-Ecology-and-Management 76(1/3): 55-67.
Keywords: release treatments
chemical release
manual release
growth
tree/stand health
tree physiology
stand conditions
Abstract:
Responses of competing vegetation and planted Douglas fir (Pseudotsuga
menziesii var. menziesii) were studied for 10 years after six herbicide and
manual release treatments in the Washington and Oregon Coast Ranges. Studies
were installed in six 2- or 3-yr-old plantations, with Douglas fir densities of
988 to 1482 plants/ha at time of planting and 721 to 1282/ha 2 to 3 years late.
Research objectives were to quantify regional, long-term responses of
vegetation (Douglas fir and non-coniferous species) to various levels of
competition, light and soil water availability, and intensity versus importance
of factors influencing Douglas fir growth. Three treatments reduced shrub cover
relative to the untreated check: triclopyr in year 1, glyphosate in years 1-5,
and repeated control (via several herbicide applications) in years 1-10.
Reductions in woody cover from glyphosate stimulated increases in herb cover in
years 3 and 5, while repeated control reduced herb cover in years 1, 2 and 5.
Through year 10, Douglas fir survival (86-99%) varied little among treatments.
Visual symptoms of herbicide injury to Douglas fir from triclopyr (45% of
trees) and glyphosate (17% of trees) were associated with 0.1-0.2 m reductions
in first-year height. After adjusting for tree size, Douglas fir growth in stem
basal area 2 years after triclopyr was less than that of the untreated check,
suggesting prolonged effects of herbicide injury. Because it sustained low
levels of interspecific competition, caused minimal tree injury, and prevented
overtopping cover from red alder (Alnus rubra), repeated control was the only
treatment in which Douglas fir size (9.8 m height and 21 cm basal diameter in
year 10) significantly exceeded (P<less or =>0.02) that of the untreated
check (7.8 m height and 12 cm diameter).
26. Helgerson, O.T. 1990b. Response of underplanted Douglas-fir to herbicide injection of
sclerophyll hardwoods in southwest
Keywords: nursery operations
release treatments
chemical release
stand conditions
tree physiology
tree/stand health
growth
Abstract:
Low-value broadleaf sclerophyll forests in
27. Hermann, R.K. and D.P. Lavender.
1999. Douglas-fir planted forests. New-Forests 17(1/3): 53-70.
Keywords: genetic tree improvement
nursery operations
planting operations
site preparation
release treatments
fertilization
thinning
pruning
tree/stand protection
growth
yield
Abstract: A
combination of superior wood quality and high productivity has made Douglas fir
(Pseudotsuga menziesii) one of the premier timber trees in the world. As such,
it is grown as a plantation species in several countries in
28.
Keywords: release treatments
manual release
stand conditions
tree physiology
growth
Abstract: In
29. Jaindl, R.G. and S.H. Sharrow.
1988. Oak/Douglas-fir/sheep: a three-crop silvopastoral system.
Agroforestry-Systems 6(2): 147-152.
Keywords: planting operations
release treatments
manual release
tree/stand health
growth
Abstract: A small
scale agroforestry study started in 1952 was revisited in 1985 to evaluate the
long-term influence of site preparation and grazing on tree growth and survival
in a system with Douglas fir, white oak (Quercus garryana) and sheep. In
1952-53, 2-yr-old Douglas fir seedlings were planted at the rate of 2500
trees/ha under 3 levels of site preparation: (1) no treatment; (2) oak thinned
by 50%; and (3) oak clear felled. From 1954 to 1960, yearling ewes grazed half
of each of the 3 thinning treatments for 3-4 wk each spring. The conifers were
undisturbed since grazing was discontinued in 1960. Survival of planted
conifers averaged 64% in 1985 and did not vary among either site preparation or
grazing treatments. From 1964 to 1985, trees on the thinned and clear felled
plantations grew an av. ht. of 1060 and 990 cm, respectively, compared with 900
cm on the unthinned plantation. D.b.h. averaged 3.8 and 5.6 cm greater on
thinned or clear felled plantations, respectively, than on the unthinned
control by 1985. Conifers on grazed plantations had increased ht. and d.b.h.
growth during the first 12 yr of plantation life, averaging 63 cm taller and
0.7 cm greater in d.b.h. than the ungrazed plots by 1964. By 1985 the
difference in ht. (122 cm) and d.b.h. (1.0 cm) between grazed and ungrazed
plantations was not statistically significant. These data suggest that although
site preparation can positively influence conifer growth, total clear felling
is no better than thinning oaks. Furthermore, proper grazing can increase ht.
and d.b.h. growth of the conifers during and immediately after the grazing
years.
30. Karl, M.G. and P.S. Doescher.
1993. Regulating competition on conifer plantations with prescribed cattle
grazing. Forest-Science 39(3): 405-418.
Keywords: release treatments
manual release
stand conditions
tree physiology
soil properties
Abstract: On conifer
plantations, competitive understorey vegetation often retards growth and
establishment of tree seedlings. Livestock grazing is one method of controlling
the understorey vegetation and increasing the availability of site resources to
tree seedlings. It was hypothesized that prescribed cattle grazing ameliorates
water stress of young tree seedlings by reducing root growth of competing
understorey species. On a Douglas-fir (Pseudotsuga menziesii) and ponderosa
pine (Pinus ponderosa) plantation in
31. Kelpsas, B.R. 1987. Seasonal
impacts of fluroxypyr and triclopyr on conifers and shrubs.
Proceedings-of-the-Western-Society-of-Weed-Science (Vol.40): 128-129.
Keywords: release treatments
chemical release
tree/stand health
stand conditions
Abstract: Release
of Pseudotsuga menziesii from Rubus spectabilis and Alnus rubra in a plantation
in the
32. Ketchum, J.S., R. Rose and B.
Kelpsas. 2000. Comparison of adjuvants used in fall-release herbicide mixtures
for forest site preparation. Tree-Planters' Notes 49(3): 66-71.
Keywords: site preparation
chemical preparation
release treatments
chemical release
tree/stand health
stand conditions
Abstract: Tank
mixes of the herbicides imazapyr and glyphosate were applied at 3 rates with 3
adjuvants (LI-700Reg., Nu-Film-IRReg., Silwet L-77Reg.) over
33. Knapp, W.H., T.C. Turpin and J.H.
Beuter. 1984. Vegetation control for Douglas-fir regeneration on the
Keywords: planting operations
site preparation
chemical preparation
mechanical preparation
prescribed fire
release treatments
chemical release
manual release
growth
yield
economics
Abstract: Records
from 324 plantations in
34.
Keywords: release treatments
chemical release
manual release
growth
tree morphology
Abstract: Height-age
and height-diameter models for plantations of young Douglas fir (Pseudotsuga
menziesii var. menziesii) were examined in relation to vegetation management
treatments. The models were developed from 10 years of measurements in a
competition release study installed on six sites in the Coast Ranges of Oregon
and Washington. Analysis of height growth patterns for dominant trees indicated
significant differences between the total vegetation control treatment and operational
release treatments or no treatment. The resulting height-age function depicted
exponential growth patterns for the total vegetation control treatment and
nearly linear patterns for the operational release treatment and no treatment.
The height-diameter function was compatible with dominant height growth and
quadratic mean diameter prediction functions. Different height-diameter curve
shapes were associated with total vegetation control and the operational
release and no treatments. The resulting function implied that Douglas fir
trees of a given diameter and age were slightly taller when under interspecific
competition, especially for trees with smaller diameters. The height-age and
height-diameter functions may be used in conjunction with diameter distribution
or stand table projection models developed for these data to predict dynamics
and stand structure in young Douglas fir plantations.
35.
Keywords: release treatments
chemical release
growth
tree morphology
Abstract: A stand
table projection system based on individual-tree and stand-level models for
young Douglas fir (Pseudotsuga menziesii var. menziesii) plantations was
developed from and evaluated with remeasurement data from xeric sites in the
Siskiyou Mountains of SW Oregon (established in a competition gradient study),
and mesic sites in the Coast Ranges of Oregon and Washington (established in a
treatment efficacy study). A projection equation was developed for relative
tree size, defined as the ratio of individual-tree diameter at 15 or 30 cm
above ground level (depending on the study location) to quadratic mean
diameter. The relative size projection equation for the