Growth of Douglas-fir in Southwestern Oregon after removal of competing vegetation.

1988 ◽  
Author(s):  
Annabelle E. Jaramillo
Keyword(s):  
Douglas Fir ◽  
Competing Vegetation

Effects of logging debris treatments on five-year development of competing vegetation and planted Douglas-fir

2010 ◽  
Vol 40 (3) ◽  
pp. 500-510 ◽  
Author(s):  
Timothy B. Harrington ◽  
Stephen H. Schoenholtz
Keyword(s):  
Forest Regeneration ◽  
Timber Harvest ◽  
Douglas Fir ◽  
Soil Productivity ◽  
Short Term ◽  
Vegetation Control ◽  
Competing Vegetation ◽  
Scotch Broom ◽  
Considerable Research ◽  
Survival And Growth

Although considerable research has focused on the influences of logging debris treatments on soil and forest regeneration responses, few studies have identified whether debris effects are mediated by associated changes in competing vegetation abundance. At sites near Matlock, Washington, and Molalla, Oregon, studies were initiated after timber harvest to quantify the effects of three logging debris treatments (dispersed, piled, or removed) on the development of competing vegetation and planted Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii ). Each debris treatment was replicated with initial and annual vegetation control treatments, resulting in high and low vegetation abundances, respectively. This experimental design enabled debris effects on regeneration to be separated into effects mediated by vegetation abundance and those independent of vegetation abundance. Two to three years after treatment, covers of Scotch broom ( Cytisus scoparius (L.) Link) at Matlock and trailing blackberry ( Rubus ursinus Cham. & Schltdl.) at Molalla were over 20% greater where debris was piled than where it was dispersed. Debris effects on vegetation abundance were associated with 30% reductions in the survival of Douglas-fir at Matlock (r2 = 0.62) and the stem diameter at Molalla (r2 = 0.39). Douglas-fir survival and growth did not differ among debris treatments when effects were evaluated independent of vegetation abundance (i.e., with annual vegetation control), suggesting negligible short-term effects of debris manipulation on soil productivity.

Response of coastal Douglas-fir and competing vegetation to repeated and delayed weed control treatments during early plantation development

2009 ◽  
Vol 39 (6) ◽  
pp. 1208-1219 ◽  
Author(s):  
Douglas A. Maguire ◽  
Douglas B. Mainwaring ◽  
Robin Rose ◽  
Sean M. Garber ◽  
Eric J. Dinger
Keyword(s):  
Weed Control ◽  
Seedling Growth ◽  
Volume Growth ◽  
Douglas Fir ◽  
Optimal Regime ◽  
Competitive Effects ◽  
Competing Vegetation ◽  
Plantation Development ◽  
Age Shift

A key silvicultural decision in managing young conifer plantations is determining the number and timing of release treatments to control competing vegetation. Three coastal Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plantations were treated under eight alternative herbicide regimes during the first 5 years after planting to test treatment effects on vegetation dynamics and seedling growth. After termination of herbicide treatments, competing vegetation developed at a rate similar to that of check plots, reaching 40%–60% cover in the first growing season and approaching 100% by the third. Recovery of competing vegetation was slightly more rapid with greater number of previous releases. Annual volume growth of seedlings was negatively correlated with current cover of competing vegetation, but competitive effects from previous years were fully accounted for by initial tree size. Under 4 years of release, delaying treatment by 1 year reduced volume attained at the end of 5 years by about 15%. Plots receiving 5 consecutive years of weed control reached the 5 year volume of check plots in only 3.9 years, implying an age shift of 1.1 years. Increasing the number of operational release treatments significantly improved seedling growth in the short term, but long-term growth effects must be monitored to determine the economically optimal regime.

Soil and Douglas-fir (Pseudotsuga menziesii) foliar nitrogen responses to variable logging-debris retention and competing vegetation control in the Pacific Northwest

2010 ◽  
Vol 40 (2) ◽  
pp. 254-264 ◽  
Author(s):  
Robert A. Slesak ◽  
Timothy B. Harrington ◽  
Stephen H. Schoenholtz
Keyword(s):  
Pacific Northwest ◽  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Soil N ◽  
Vegetation Control ◽  
Competing Vegetation ◽  
Total Soil ◽  
The Pacific ◽  
N Acquisition ◽  
Total Soil N

Experimental treatments of logging-debris retention (0%, 40%, or 80% surface coverage) and competing vegetation control (initial or annual applications) were installed at two sites in the Pacific Northwest following clearcutting Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. menziesii) stands to assess short-term effects on tree N acquisition, soil N supply, and total soil N. Vegetation control treatments began in the first year after harvest, and logging-debris manipulations were installed 2 years after harvest. Annual vegetation control increased foliar N concentration and content in most years at both sites, which was associated with higher available soil N and increased soil water content. Logging-debris retention treatments had no detectable effect on any of the foliar variables or soil available N at either site. There were no treatment effects on total soil N at the site with relatively high soil N, but total soil N increased with logging-debris retention when annual vegetation control was applied at the site with a low initial soil N pool. Competing vegetation control is an effective means to increase tree N acquisition in the initial years after planting while maintaining soil N pools critical to soil quality. The effect of logging-debris retention on tree N acquisition appears to be limited during early years of stand development, but increased soil N with heavy debris retention at certain sites may be beneficial to tree growth in later years.

scholarly journals Twenty-Year Response of Ponderosa Pine (Pinus ponderosa Laws.) to Treatment with Hexazinone in Northeastern Oregon

2009 ◽  
Vol 24 (3) ◽  
pp. 151-156
Author(s):  
Amanda Lindsay ◽  
Paul Oester ◽  
Elizabeth Cole
Keyword(s):  
Pseudotsuga Menziesii ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Seedling Survival ◽  
Douglas Fir ◽  
Individual Tree ◽  
Growth And Survival ◽  
Competing Vegetation ◽  
Plant Associations ◽  
Initial Control

Abstract Chemical control of competing vegetation with hexazinone is a common and effective silvicultural treatment for ensuring ponderosa pine (Pinus ponderosa Laws.) plantation success on dry sites in the western United States, yet few studies document the effect for more than the first few years after planting. This study, re-evaluated 20 years after planting, followed ponderosa pine growth and survival when hexazinone was applied in broadcast and spot treatments for control of competing vegetation. We continued work from the first 5 years after establishment that identified early differences in ponderosa pine seedling survival and growth with treatment. Examination of 20-year trends indicated that individual tree volume and volume per hectare continued to diverge among treatments. The economic differences among treatments may increase as more surviving, faster-growing trees in the broadcast treatments reach higher-value products sooner. Initial control of competing vegetation increased the likelihood of seedling survival and increased tree size after 20 years. Results pertained to ponderosa pine of the Douglas-fir/spiraea (Pseudotsuga menziesii var. glauca Beissn./Spiraea betulifolia Pall.) and Douglas-fir/common snowberry (Pseudotsuga menziesii var. glauca Beissn./Symphoricarpos albus [L.] S. F. Blake) plant associations in northeastern Oregon, but they should apply to similar sites throughout much of the intermountain West.

Competing Vegetation Effects on Soil Carbon and Nitrogen in a Douglas-fir Plantation

2014 ◽  
Vol 78 (S1) ◽  
pp. S146-S151 ◽  
Author(s):  
Erika Knight ◽  
Paul Footen ◽  
Robert Harrison ◽  
Thomas Terry ◽  
Scott Holub
Keyword(s):  
Soil Carbon ◽  
Douglas Fir ◽  
Vegetation Effects ◽  
Carbon And Nitrogen ◽  
Competing Vegetation ◽  
Soil Carbon And Nitrogen

scholarly journals Time vs. light: a potentially useable light sum hybrid model to represent the juvenile growth of Douglas-fir subject to varying levels of competition

2007 ◽  
Vol 37 (4) ◽  
pp. 795-805 ◽  
Author(s):  
E. G. Mason ◽  
R. W. Rose ◽  
L. S. Rosner
Keyword(s):  
Site Occupancy ◽  
Vapour Pressure Deficit ◽  
Douglas Fir ◽  
Meteorological Station ◽  
Water Vapour Pressure ◽  
Crop Species ◽  
Competing Vegetation ◽  
Competition Control ◽  
Competition For Light ◽  
Water Vapour Pressure Deficit

Substitution of potential useable light sum for time in a commonly used mensurational equation resulted in a better fit to data from a complex vegetation management experiment. The experiment involved Douglas-fir ( Pseudotsuga menzeisii (Mirb.) Franco) as a crop species and a variety of competing species. Site occupancy by competing vegetation varied with time because control operations were intermittently either included or excluded from treatments over a period of 4 years. There were four randomized complete blocks of eight competition control treatments. Potentially useable light sum was estimated using measurements of radiation from a meteorological station that were modified by coefficients representing the ability of the crop plants to use light with varying soil water, vapour pressure deficit, and temperature. Light sums were further reduced by estimated competition for light from competing vegetation. Fits of the model to individual plots within the experiment yielded coefficients that did not differ significantly between competition control treatments, suggesting that the model accounted for significant variations in growth resource availability between treatments. Potentially useable light sum equations provide an integrated link between traditional mensurational modeling and ecophysiological modeling.

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