1. 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 Pacific Northwest region. Applications were made at 4 times: 3 month pre-planting in Dec., as buds began to swell in Mar., during the spring flush of growth in May, and after bud set in Aug. The effect of different application rates was of less significance than their timings. Application during active growth gave unacceptable injury levels; pre-planting caused least injury, but autumn treatment was acceptable for tolerant species. Species tolerance was in the order Pinus ponderosa > Pseudotsuga menziesii > T. heterophylla > A. amabilis.

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2. 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.

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3. 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.

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4. 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 United States for site preparation and control of competing vegetation. How non-target soil biota respond to herbicide applications, however, is not thoroughly understood. We tested the effects of triclorpyr, imazapyr, and sulfometuron methyl on ectomycorrhizal formation in a greenhouse study. Ponderosa pine, Douglas-fir, and white fir seedlings were grown in four forest soils ranging in clay content from 9 to 33% and organic matter content from 3 to 17%, and treated with commercial formulations of each herbicide at 0, 1.0, and 2.0 times the recommended field rate. Many of the possible herbicide-soil combinations resulted in reduced seedling growth. Root development was particularly sensitive to the three herbicides, with an average of 51% fewer root tips compared to the control treatment. The ability of mycorrhizal fungi to infect the remaining root tips, however, was uninhibited. Mycorrhizal formation was high, averaging 91% of all root tips, regardless of herbicide, application rate, soil type, or conifer species. In agreement, soil microbial biomass and respiratory activity were unaffected by the herbicide treatments. The results show that these herbicides do not alter the capability of mycorrhizal fungi to infect roots, even at concentrations detrimental to seedling growth.

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5. 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 Oregon Coast Range. Crowding and competition from both grass and alder reduced aboveground dry wt. per tree. Dry wt./ha was higher at higher tree densities, but this is expected to change with time as the larger trees at low densities form fully stocked stands. Grass showed the greatest effect on growth at the driest site. Although red alder decreased growth on all sites, the effect was most significant at the coastal site where light is most limiting and moisture least limiting. For the production of max. individual tree size, low stocking with control of competing vegetation is recommended.

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6. 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.

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7. 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.

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8. 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 Oregon in 1984-85. Arsenal produced the most complete and consistent control of Acer macrophyllum when applied in late summer, but early summer applications were more effective against the sclerophyll brush species Arbutus menziesii, Ceanothus velutinus var. laevigatus, Arctostaphylos columbiana and A. viscida. High rates of Arsenal gave good control of Alnus rubra and Rubus spectabilis, but did not control R. laciniatus or R. procerus. On all the controlled species, growth of new foliage was decreased or prevented. DPX-T6376 reduced the crown vol. of A. macrophyllum and killed the sclerophyll brush species, all Rubus spp. but not A. rubra. Both chemicals produced severe injury to P. menziesii.

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9. Cole, E.C., M. Newton and D.E. White. 1988. Efficacy of imazapyr and metsulfuron methyl for site preparation and conifer release in the Oregon Coast Range. Forest-Research-Laboratory,-Oregon-State-University Research-Note 81. 7 p.

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 Oregon Coast Range. Imazapyr was highly effective on red alder (Alnus rubra) and bigleaf maple (Acer macrophyllum), but was less effective on salmonberry (Rubus spectabilis) and other blackberry (Rubus) species. Metsulfuron-methyl was ineffective on red alder and bigleaf maple, but gave excellent control of salmonberry, Himalaya blackberry (R. procerus) and evergreen blackberry (R. laciniatus). Both chemicals caused severe injury to Douglas fir seedlings, especially when applied during the growing season. It is concluded that these herbicides are promising for site preparation, but have limited use for release of Douglas fir.

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10. 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-Forest-Service Research-Paper PNW-RP-280. iii + 16 p.

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 Oregon in 1975, herbicides were spot sprayed around individual seedlings. In 2 studies in Washington and Oregon in 1976, herbicides were broadcast sprayed. The mixture consistently controlled grass and forbs better than either herbicide alone, reducing grass and forb cover respectively by 80-82% and 48-58% in the first year. Control persisted for 2-4 yr. Varying results are reported as to the effects of the different treatments on height growth and survival.

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11. 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.

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12. 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 SW Washington. Two 6-year-old plantations had streamside buffer zones remaining from the previous year's operational herbicide spray programme; the 3rd was a 13-year-old plantation which had not been previously treated with herbicides to control A. rubra. The treatments tested were as follows: 50% triclopyr, 45% glyphosate and 10% imazapyr applied to the cut stump surface; low-vol. basal application of 5, 10 and 15% triclopyr and 2 and 4% imazapyr; thin-line application of 50, 75 and 100% triclopyr and 20 and 40% imazapyr; stream-line application of 10, 30 and 50% triclopyr and 4 and 20% imazapyr; hack-and-squirt application with imazapyr applied to 1 cut at 0.25, 0.5 and 0.75 ml and to 2 cuts at 0.25 and 0.5 ml; and capsule injection of 1 or 2 glyphosate capsules. A discussion of the results is presented and total treatment costs are given. It is concluded that ground application treatments have advantages over aerially applied treatments, including being useful for the treatment of areas of public sensitivity and when other environmental risks need to be minimized.

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13. 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.

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14. 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 6 Dec. 1990, 6 Feb. 1991 and 11 Apr. 1991, and triclopyr + picloram at 1 + 0.5 lb was applied on 6 Feb. 1991 using thinline applications to the entire circumference of each stem in the bigleaf maple clump. The threshold level of Garlon for <more or =>90% control was found to be between 1.1 and 1.7 ml/msuperscript 2 of crown area. Most treatments produced clumps that appeared to be dead during the 1st year but which resprouted in the 2nd year; it is suggested that such inconsistencies in mortality among treatments are due to the inability to completely band every stem. Economic considerations for herbicide costs are discussed.

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15. 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.

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16. 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 Marquam, Oregon, during 1988-90, the tolerance was evaluated of douglas-fir [Pseudotsuga menziesii] seedlings to triclopyr ester and triclopyr amine (both applied at 0.5-1.5 lb/acre) during the 1st 2 years after transplanting. Triclopyr amine did not cause significant damage to 1- or 2-year-old plants. Triclopyr ester in a water carrier resulted in injury to terminal buds of 1-year-old plants when applied at 1.5 lb, and in a diesel carrier resulted in damage to lateral and terminal buds when applied at concn of <more or =>1.0 lb. Two-year-old plants were more tolerant than 1-year-old plants to both triclopyr formulations, with triclopyr ester at 1.5 lb in a water carrier resulting in only slight needle injury. However, in a diesel carrier, triclopyr ester at 1.5 lb still resulted in terminal and lateral bud damage.

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17. Flint, L.E. and S.W. Childs. 1987. Effect of shading, mulching, and vegetation control on Douglas-fir seedling growth and soil water supply. Forest-Ecology-and-Management 18(3): 189-203.

Keywords: release treatments

chemical release

manual release

growth

soil properties

Abstract: Harsh environments on many harvested sites in SW Oregon necessitate site modifications for successful regeneration of Douglas fir. A 2-yr study was made with 350 seedlings to assess the effects of 12 soil-surface shading, mulching, and vegetation control techniques on seedling growth and soil temp. and moisture environments. Major effects of treatments were to lower soil surface temp., reduce soil surface evaporation, and reduce vegetative competition for soil water. These affected seedlings by adjusting the timing of seedling growth and reducing soil water loss to increase available water for seedling use. Final seedling shoot vol. and stem diam. both differed among treatments. Seedlings in treatments where competing vegetation was controlled showed significantly greater growth than seedlings in other treatments. Soil water loss in treatments where either soil surface evaporation was controlled by mulching, or where competing vegetation was controlled, was significantly less than water loss from the shaded and control treatments. Soil water loss in treatments with vegetation controlled by herbicide was significantly less than in treatments with vegetation controlled by scalping. Seedlings showed greatest growth with treatments that elicited the most efficient use of available microsite water either by reducing soil surface evaporation or vegetation competition.

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18. Gourley, M., M. Vomocil and M. Newton. 1990. Forest weeding reduces the effect of deer-browsing on Douglas fir. Forest-Ecology-and-Management 36(2-4): 177-185.

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 Oregon Coast Range where browsing by black tail deer (Odocoileus hemionus columbiana) was expected. Protection was provided against browsing by 5 physical (rigid protection tube 7.5x75 cm; protective netting, paper budcaps; leather guard 20x5 cm; and 'Remae' budcaps) and one chemical ('Deer Away') treatment, each of which was tested with and without complete wood control with glyphosate. After five years, none of the protective treatments provided any growth advantages; some even caused growth losses. In contrast, weed control, with or without additional protective measures, consistently improved growth. By the 5th year, weeded trees averaged twice the biomass of unweeded trees, regardless of browsing. Average tree size was largest in the treatment with no weed competition and with no barriers to prevent browsing. Advantages of weeding were greatest on the poorest site. Weed control, in conjunction with the large size of transplants, appeared to prevent most loss due to damage from moderate deer-browsing.

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19. 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 Pacific Northwest region of the United Sates. The analysis included uncertainty in the price trends and stocking levels of both species following reforestation. Results from a case study in which Douglas fir price is likely to increase faster than red alder price show that (i) on more productive sites, greater regeneration investment is justified to increase the likelihood of Douglas fir establishment, (ii) on less productive sites, low-cost regeneration options that produce mixed-species stands have expected present values close to or greater than a high-cost Douglas fir regeneration effort, (iii) optimal precommercial removal of red alder depends on mid-rotation prices and regeneration success, and in many cases growing a mixed-species stand to maturity produces the highest economic return, and (iv) commercial thinning of Douglas fir increases the expected present value of the most intensive regeneration option by up to 10%. The low-cost regeneration options have relatively high expected returns because of low initial investments and the presence of two species that may have high values in the future. The sensitivity of these results to changes in the probability distributions of regeneration success and price trends is discussed.

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20. Haight, R.G. 1993b. Technology change and the economics of silvicultural investment. Rocky-Mountain-Forest-and-Range-Experiment-Station,-USDA-Forest-Service General-Technical-Report RM-GTR-232. ii + 18 p.

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.

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21. 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).

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22. 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 nursery-grown 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.

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23. 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 Pacific Northwest could be achieved by 1.12 kg fluroxypyr/ha applied in May at the early foliar stage without appreciable long-term injury. P. menziesii tolerated 1.12 kg triclopyr/ha but was severely damaged by 1.12 kg and 2.24 kg fluroxypyr when applied during the dormant season in Mar. Both fluroxypyr and triclopyr were more effective against A. rubra than R. spectabilis. Control of R. spectabilis with triclopyr was marginal.

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24. 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 California hazelnut (Corylus cornuta var. californica), vine maple (Acer circinatum), and brackenfern (Pteridium aquilinum var. lanuginosum) on a 2-year-old clearcut of Douglas fir (Pseudotsuga menziesii) in Oregon. The herbicide 2,4-D was applied at 3 rates with 2 adjuvants (HerbimaxReg., Nu-Film-IR) over greenleaf manzanita (Arctostaphylos patula) on a 4-year-old Douglas fir clearcut in Oregon. Tank mixes of imazapyr and glyphosate with LI-700 or Nu-Film-IR were sprayed at 3 rates over 1-year-old seedlings of Douglas fir on 2 sites in Oregon. The herbicide rate strongly influenced the percentage of foliage injured and percentage of stems killed for all herbicide treatments. The adjuvants evaluated did not influence efficacy of herbicide applications on California hazelnut, vine maple, or brackenfern. Herbimax increased visual foliar damage resulting from 2,4-D application on greenleaf manzanita. Douglas fir foliage was damaged by the higher herbicide rates; the damage was greater from Nu-Film-IR than from LI-700.

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25. Knapp, W.H., T.C. Turpin and J.H. Beuter. 1984. Vegetation control for Douglas-fir regeneration on the Siuslaw National forest: a decision analysis. Journal-of-Forestry 82(3): 168-173.

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 Oregon were used to calculate the effect on stocking of various methods of controlling competing vegetation before and after plantation establishment. A decision tree analysis using 6 management regimes on 5 stocking classes indicated that if no site preparation or release (other than broadcast burning to reduce fuels) were practised, the forest would produce 63% of the m.a.i. and 35% of the present net worth (PNW) expected if all means of control (chemical, manual and burning) were available and used. If only manual control methods were used 78% of the max. m.a.i. and 57% of the max. PNW would be expected. When all methods except phenoxy herbicides were available, the expected m.a.i. and PNW were reduced to no less than 90%. The yield reduction varied with aspect, and the type of prelogging vegetation. Declines were least on SW-facing sites that were originally predominantly conifers, and greatest on NE-facing slopes that had supported broadleaves. Limitations of the analysis are discussed.

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26. Knowe, S.A. 1994a. Effect of competition control treatments on height-age and height-diameter relationships in young Douglas-fir plantations. Forest-Ecology-and-Management 67(1-3): 101-111.

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.

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27. Knowe, S.A. 1994b. Incorporating the effects of interspecific competition and vegetation management treatments in stand table projection models for Douglas-fir saplings. Forest-Ecology-and-Management 67(1-3): 87-99.

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 Coast Ranges study included the effect of total vegetation control, which indicated that diameters of Douglas fir receiving total vegetation control tended to become more uniform over time in the Coast Ranges. An additional equation was developed to project quadratic mean diameter so that individual-tree diameters could be estimated from projected relative size. The effect of vegetation management treatments on projected quadratic mean diameters in the Siskiyou study was expressed as an interaction between proportion of cover removed by treatments (intensity) and dominant height of Douglas fir at time of treatment relative to current dominant height. In 1- and 2-yr projection periods, the stand table projection system performed similarly to a diameter distribution prediction system based on a Weibull distribution function. However, the difference between projected and predicted diameter distributions became more pronounced as the projection period increased to 5 years.

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28. 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 Douglas-fir 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, 50th, 95th) of the cumulative probability distribution were predicted as functions of quadratic mean diameter and age. In the Siskiyou study, cover and total vegetation control affected quadratic mean diameter and all four percentiles; intensity of the vegetation treatments affected the 0 and 25th percentiles, and the interaction between intensity and timing of treatment affected mean diameter. In the Coast Ranges study, only quadratic mean diameter was affected by cover of woody vegetation, while quadratic mean diameter and the 25th percentile were significantly affected by total vegetation control. The predicted distributions showed decreasing variance with increasing cover, particularly in the Siskiyou Mountains. In the Coast Ranges study, the coefficient of variation increased with increasing cover, indicating that the variance of stem diameters was affected by average size. On xeric sites in the Siskiyou Mountains, high diameter variability in plots with total vegetation control suggests that interspecific competition may inhibit the expression of microsite variation.

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29. McDonald, P.M. and G.O. Fiddler. 1993. Feasibility of alternatives to herbicides in young conifer plantations in California. Canadian-Journal-of-Forest-Research 23(10): 2015-2022.

Keywords: genetic tree improvement

site preparation

prescribed fire

release treatments

manual release

chemical release

growth

economics

Abstract: A research programme (involving 40 studies) was started in 1980 to compare the effectiveness and cost of various vegetation management techniques used for enhancing growth of 1- to 3-yr-old conifer (Pseudotsuga menziesii, Pinus ponderosa, P. jeffreyi, Abies magnifica and A. concolor var. lowiana) plantations in California. The studies were ended after 10 yr when competition became intraspecific. The techniques used included direct methods such as manual manipulation, mulching, herbicides (Garlon 3A [triclopyr], 2,4-D or Velpar [hexazinone]), and grazing for releasing conifer seedlings from undesirable vegetation, and several silvicultural practices (broadcast burning, group selection, genetically improved seedlings) that serve as indirect methods for reducing or avoiding vegetation problems. Manual release and mulching were effective but expensive. Herbicides were effective, applicable to almost all plant communities, and relatively inexpensive. Grazing was good for cattle and sheep, but did not significantly enhance conifer seedling growth. Silvicultural control of weeds was promising, but there was not enough information to evaluate feasibility. It was concluded that in most instances, forests cannot be managed economically without herbicides, if the objective is to grow seedlings at the potential of the site and the plant community includes sprouting broadleaves and shrubs or rhizomatous forbs and ferns. If the objective is to create a forest with several age-classes and variable structure, but with slower seedling growth, longer rotations, and less species diversity in early seral stages, then it is possible to accomplish this using other vegetation management techniques.

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30. McDonald, P.M. and G.O. Fiddler. 1996. Development of a mixed shrub-tanoak-Douglas-fir community in a treated and untreated condition. Pacific-Southwest-Research-Station, USDA-Forest-Service Research-Paper PSW-RP-225. iv + 16 p.

Keywords: release treatments

manual release

chemical release

tree/stand health

growth

tree morphology

stand conditions

economics

Abstract: On a medium site in northern California, a tanoak (Lithocarpus densiflorus)-mixed shrub community in a Douglas fir plantation was given several treatments (manual release two and three times, a combination chainsaw and cut surface herbicide (Garlon 3A [triclopyr]) treatment, two foliar herbicides (2,4-D or Garlon 4), and a tank mix of the two herbicides) to study its development in both a natural (control) and treated condition. The herbicides were each applied twice. Survival of planted Douglas fir (Pseudotsuga menziesii) seedlings was recorded for 11 years and growth was quantified for 9 years after the last treatment application. In addition to Douglas fir, data are presented individually for the two most abundant species (tanoak and snowbrush, Ceanothus velutinus var. hookeri), for greenleaf manzanita (Arctostaphylos patula), and for the hardwood tree and shrubs combined. At the study's end in 1992, combined vegetation in the control had a mean density of 1800 plants/acre, foliar cover of 23 700 ftsuperscript 2/acre, and height of 11.2 ft. In contrast, combined tree and shrubs in the most effective treatment for controlling them (cut and spray Garlon 3A) had a mean density of 150 plants/acre, foliar cover of 150 ftsuperscript 2/acre and height of 5.9 ft at study end. Because competition for site resources was low, Douglas fir seedlings developed best in this treatment. Mean Douglas fir diameter was 4.6 inches at 12 inches above mean ground line, height averaged more than 21 ft, and mean foliar cover was 39 850 ftsuperscript 2 at the end of the study. The cost was $227 per acre.

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31. McDonald, P.M. and G.O. Fiddler. 1999. Ecology and development of Douglas-fir seedlings and associated plant species in a Coast Range plantation. Pacific-Southwest-Research-Station, USDA-Forest-Service Research-Paper PSW-RP-243. ii + 18 p.

Keywords: release treatments

manual release

chemical release

stand conditions

growth

tree morphology

economics

Abstract: