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.

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 Douglas-Fir Biomass Allocation and Net Nutrient Pools 15–20 Years after Organic Matter Removal and Vegetation Control

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1022
Author(s):  
K. M. Littke ◽  
T. B. Harrington ◽  
S. M. Holub ◽  
W. R. Littke ◽  
R. B. Harrison ◽  
...  
Keyword(s):  
Organic Matter ◽  
Biomass Allocation ◽  
Douglas Fir ◽  
Soil Productivity ◽  
Soil Base ◽  
Nutrient Pools ◽  
Vegetation Control ◽  
Old Trees ◽  
Whole Tree

Douglas-fir (Pseudotsuga menziesiivar. menziesii (Mirbel) Franco) plantation forests of the coastal Pacific Northwest have been intensively managed to improve the yield of forest products. However, the long-term effects of these management techniques have received limited research attention in this region. Three affiliate Long-Term Soil Productivity study sites were installed in Douglas-fir forests to understand the impacts of organic matter removals and vegetation control on soil productivity over time. Matlock and Fall River are located in Washington, USA and Molalla is located in Oregon. Organic matter removal treatments included traditional bole-only harvest (BO), whole tree removals (WT), and a whole tree plus coarse woody debris removal (WT+) (Fall River only). Five years of annual vegetation control (AVC) was compared with a conventional initial vegetation control (IVC) treatment at all sites. Douglas-fir biomass allocation to foliage, branch, and stem components was modeled using 15- to 20-year-old trees from this study along with 5- to 47-year-old trees from previous studies on these sites. Across all sites, model predictions indicated that the WT treatment had 7.1 to 9.7 Mg ha−1 less Douglas-fir biomass than the BO treatment. There was 1.5 to 20.5 Mg ha−1 greater Douglas-fir biomass in the AVC treatment than in the IVC treatment at all sites. Douglas-fir carbon and nitrogen biomass were consistently lower in the WT treatment, but there were no significant changes in overall site nutrient pools. The AVC treatment resulted in greater Douglas-fir nutrient pools yet there was a net loss in site calcium, magnesium, and potassium due to lower forest floor and soil base cation pools. While WT removals did not significantly affect site nutrition, the decrease in Douglas-fir biomass at all sites and increase in invasive Scotch broom (Cytisus scoparius (L.) Link) biomass at Matlock suggests that the standard practice of retaining harvest residuals is beneficial. The use of intensive vegetation control to improve Douglas-fir biomass and nutrition must be balanced with retaining soil base cations.

The Effect of High Concentrations of Ethylene on Seed Germination of Douglas Fir (Pseudotsugamenziesii (Mirb.) Franco)

1975 ◽  
Vol 5 (3) ◽  
pp. 419-423 ◽  
Author(s):  
Carey Borno ◽  
Iain E. P. Taylor
Keyword(s):  
Seed Germination ◽  
Germination Rate ◽  
Inhibitory Effect ◽  
Germination Percentage ◽  
Douglas Fir ◽  
Control Treatment ◽  
Continuous Exposure ◽  
Short Term ◽  
Short Term Exposure ◽  
High Concentrations

Stratified, imbibed Douglas fir (Pseudotsugamenziesii (Mirb.) Franco) seeds were exposed to 100% ethylene for times between 0 and 366 h. Germination rate and germination percentage were increased by treatments up to 48 h. The 12-h treatment gave largest stimulation; 30% enhancement of final germination percentage over control. Treatment for 96 h caused increased germination rate for the first 5 days but reduced the germination percentage. Germinants were subject to continuous exposure to atmospheres containing 0.1 – 200 000 ppm ethylene in air, but it did not stimulate growth, and the gas was inhibitory above 100 ppm. Although some effects of high concentrations of ethylene may have been due to the lowering of oxygen supplies, this alone was insufficient to account for the full inhibitory effect. The mechanism of stimulation by short-term exposure to ethylene is discussed.

Integrated vegetation management in California – advances and future

1991 ◽  
Vol 67 (5) ◽  
pp. 528-531 ◽  
Author(s):  
Gary O. Fiddler ◽  
Philip M. McDonald
Keyword(s):  
Good Control ◽  
Vegetation Management ◽  
Bureau Of Land Management ◽  
Private Industry ◽  
Conifer Seedlings ◽  
Central California ◽  
Competing Vegetation ◽  
Growing Seasons ◽  
Survival And Growth ◽  
Mechanical Release

A study on alternatives for releasing young conifer plantations on National Forests in northern and central California was started in 1980, and enlarged to include State of California, Bureau of Land Management, and private industry lands. Forty studies involving chemical, manual, mechanical, mulch, and animal treatments have been established and their effect on the survival and growth of conifer seedlings is being quantified. Plant diversity and succession on both treated and untreated sites are being recorded. The oldest study has had 10 growing seasons since the first treatments were applied. To release conifer seedlings, a treatment radius of at least 1.5 meters is required; smaller radii do not provide enough site resources for acceptable growth. Diameter, rather than height, is the best indicator of release. Some non-phenoxy chemicals show promise for good control of competing vegetation. Mechanical release requires additional treatments to effectively control shrubs. Mulching has given limited results to date. Manual treatments, if applied to non-sprouting and nonrhizomatous plants soon after planting, and usually more than once, provide adequate control of competing vegetation, but are costly.

Invasive scotch broom alters soil chemical properties in Douglas-fir forests of the Pacific Northwest, USA

2015 ◽  
Vol 398 (1-2) ◽  
pp. 281-289 ◽  
Author(s):  
Robert A. Slesak ◽  
Timothy B. Harrington ◽  
Anthony W. D’Amato
Keyword(s):  
Pacific Northwest ◽  
Chemical Properties ◽  
Douglas Fir ◽  
Soil Chemical Properties ◽  
Scotch Broom ◽  
The Pacific

scholarly journals Root Growth Potential and Microsite Effects on Conifer Seedling Establishment in Northern Idaho

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 597
Author(s):  
Jacob A. Reely ◽  
Andrew S. Nelson
Keyword(s):  
Root Growth ◽  
Douglas Fir ◽  
Seedling Quality ◽  
Growth Potential ◽  
Larix Occidentalis ◽  
Root Growth Potential ◽  
Western Larch ◽  
Neighborhood Conditions ◽  
Seedling Performance ◽  
Survival And Growth

Environmental conditions and seedling quality interact to produce complex patterns of seedling survival and growth. Root growth potential (RGP) is one metric of seedling quality that can be rapidly measured prior to planting, but the correlation of RGP and seedling performance is not consistent across studies. Site factors including microsite objects that cast shade and competing vegetation can also influence seedling performance. We examined the effects of RGP, presence/absence of a microsite object, and competition cover on the survival and growth of three native conifers to the Inland Northwest, USA, over 5 years. We found that RGP had no effect on the survival or growth of western larch (Larix occidentalis), Douglas fir (Pseudotsuga menziesii var. glauca), and grand fir (Abies grandis) at a mesic north aspect site and a xeric south aspect site. Comparatively, the presence of a microsite increased the odds of survival by 37% for western larch and 158% for grand fir, while the absence of forb cover increased the odds of survival of western larch by 72% and of grand fir by 26%. Douglas fir was less sensitive to microsites and competition. The strong effects of neighborhood conditions around seedlings help inform silvicultural practices to enhance the establishment of western larch and grand fir, including planting seedlings near shading objects and competition control, while these practices may not be as important for Douglas fir.

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