N2 fixation by red alder (Alnus rubra) and scotch broom (Cytisus scoparius) planted under precommerically thinned Douglas-fir (Pseudotsuga menziesii)

1984 ◽  
Vol 78 (1-2) ◽  
pp. 221-233 ◽  
Author(s):  
O. T. Helgerson ◽  
J. C. Gordon ◽  
D. A. Perry
Keyword(s):  
Pseudotsuga Menziesii ◽  
N2 Fixation ◽  
Douglas Fir ◽  
Alnus Rubra ◽  
Cytisus Scoparius ◽  
Red Alder ◽  
Scotch Broom

scholarly journals Soil texture and other site-level factors differentially affect growth of Scotch broom (Cytisus scoparius) and Douglas-fir (Pseudotsuga menziesii) seedlings in the western Pacific Northwest

2021 ◽  
Author(s):  
David Carter ◽  
Robert A. Slesak ◽  
Timothy B. Harrington ◽  
Anthony W. D’Amato
Keyword(s):  
Pacific Northwest ◽  
Pseudotsuga Menziesii ◽  
Height Growth ◽  
Douglas Fir ◽  
Western Pacific ◽  
Limiting Factor ◽  
Cytisus Scoparius ◽  
Invasive Shrub ◽  
Scotch Broom ◽  
The Western Pacific

The invasive shrub Scotch broom (Cytisus scoparius (L.) Link) is a pervasive threat to regenerating Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) stands in the Pacific Northwest, USA. Field observations indicate that the susceptibility of areas to Scotch broom invasion and dominance can vary by site. We selected ten sites throughout the western Pacific Northwest that spanned a gradient of soil textures and other factors to test the site-specific susceptibility of Douglas-fir to overtopping by Scotch broom. We expected to find that the ability of Scotch broom to dominate a site was mediated by site-level factors, particularly those influencing soil water – the most limiting factor to growth in the region. We found Scotch broom and Douglas-fir were inversely affected by site-level factors. In general, Douglas-fir absolute height growth rates were more competitive with those of Scotch broom on fine-textured soils than on more coarsely textured soils. We also found Douglas-fir to have a more dramatic response to increasing down woody material than Scotch broom. Scotch broom height growth approached an asymptote at 3 m. Sites with fast-growing Douglas-fir were able to surpass this height six to seven years after planting and appear likely to avoid suppression by Scotch broom.

scholarly journals Ten-Year Survival and Growth of Planted Douglas-Fir and Western Redcedar After Seven Site-Preparation Treatments

1997 ◽  
Vol 12 (3) ◽  
pp. 74-80 ◽  
Author(s):  
William I. Stein
Keyword(s):  
Pseudotsuga Menziesii ◽  
Site Preparation ◽  
Douglas Fir ◽  
Thuja Plicata ◽  
Alnus Rubra ◽  
Red Alder ◽  
Preparation Methods ◽  
Western Redcedar ◽  
Oregon Coast ◽  
Survival And Growth

Abstract Western redcedar (Thuja plicata) and Douglas-fir (Pseudotsuga menziesii) were planted together after applying seven site-preparation methods at one site in the Oregon Coast Ranges. Survival and growth of cedar were markedly less than Douglas-fir on this favorable site where both species were components of the original stand. Repeated browsing severely impeded the cedar. Site preparation by broadcast burning generally yielded the best results, but sowing grass after broadcast burning produced Douglas-fir responses similar to those for no site preparation. Where grass was sown, herbaceous cover was more abundant and taller, salmonberry differed little in density but was slightly taller, and development of red alder (Alnus rubra) was delayed. Red alder is currently overtopping conifers in all treatments, and release is needed to ensure sufficient conifer survival. This single example illustrates that much more effort than just planting a mix of species is required to establish a desired mixed stand. West. J. Appl. For. 12(3):74-80.

Seven decades of stand development in mixed and pure stands of conifers and nitrogen-fixing red alder

2003 ◽  
Vol 33 (11) ◽  
pp. 2274-2279 ◽  
Author(s):  
Dan Binkley
Keyword(s):  
Pseudotsuga Menziesii ◽  
Mixed Stand ◽  
Alnus Rubra ◽  
Stand Development ◽  
Soil N ◽  
Ecosystem Productivity ◽  
Red Alder ◽  
The Past ◽  
River Site

Early insights on the effects of N2-fixing red alder (Alnus rubra Bong.) on conifer forests came largely from two case studies dating from the 1920s at Wind River, Washington (low soil N), and Cascade Head, Oregon (high soil N). These classic experiments were remeasured after 70 years of stand development. The pure conifer stand at Wind River showed near-zero net increment in stem mass for the past 20 years, with stem mass remaining near 120 Mg/ha. Conifer stem mass in the mixed stand continued to increase at 4.5 Mg·ha–1·year–1, reaching 230 Mg/ha at age 72. The alder mass declined over this period from about 70 Mg/ha near age 50 to just 10 Mg/ha at age 72 as a result of increasing dominance of tall Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. The pure conifer plot at Cascade Head reached a stem mass of 600 Mg/ha at age 74 years compared with 312 Mg/ha in the mixed stand (conifers, 200 Mg/ha; alder, 112 Mg/ha) and 173 Mg/ha in the pure alder plot. The long-term impacts of alder appeared to remain very strong after seven decades, greatly increasing ecosystem productivity at the N-poor Wind River site and reducing productivity at the N-rich Cascade Head site.

Silvicultural Value of Chemical Brush Control in the Management of Douglas-fir

1986 ◽  
Vol 1 (3) ◽  
pp. 69-73
Author(s):  
J. D. Walstad ◽  
J. D. Brodie ◽  
B. C. McGinley ◽  
C. A. Roberts
Keyword(s):  
Economic Value ◽  
Douglas Fir ◽  
Alnus Rubra ◽  
Economic Returns ◽  
Red Alder ◽  
The Third ◽  
Brush Control ◽  
Phenoxy Herbicides ◽  
Stand Conditions

Abstract Retrospective analyses of three conifer sites in western Oregon and Washington were conducted to determine the long-term silvicultural impact and economic value of chemical brush control treatments performed 10 to 25 years earher. Comparisons between areas treated with phenoxy herbicides and untreated areas of the sites revealed significant differences in stocking and growth of Douglas-fir (Pseudotsuga menziesii). On two sites, invading red alder (Alnus rubra) virtually excluded conifers in the absence of brush control. On the untreated area of the third site, dense growth of varnishleaf ceanothus (Ceanothus velutinus var. laevigatus) reduced Douglas-fir stocking and diameter growth. On all three sites, projections of mature yield and economic returns based on current stand conditions indicated substantial benefits for areas where brush control treatments were applied. West. J. Appl. For. 1:69-73, July 1986.

Influence of Red Alder Competition on Cambial Phenology and Latewood Formation in Douglas-Fir

IAWA Journal ◽  
2005 ◽  
Vol 26 (3) ◽  
pp. 309-324 ◽  
Author(s):  
A.T. Grotta ◽  
B.L. Gartner ◽  
S.R. Radosevich ◽  
M. Huso
Keyword(s):  
Radial Growth ◽  
Wood Quality ◽  
Basal Area ◽  
Cambial Activity ◽  
Wood Formation ◽  
Douglas Fir ◽  
Alnus Rubra ◽  
Planting Dates ◽  
Red Alder ◽  
Cambial Growth

To better understand the influence of competition on wood formation and wood quality in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco), patterns of cambial growth and latewood production were examined for one growing season in 15-year-old plantations with similar densities but differing Douglas-fir/red alder (Alnus rubra Bong.) ratios. The treatments consisted of plots having different proportions of Douglas-fir vs. red alder, different red alder planting dates, and one of two total planting densities. Cambial growth was tracked using the pinning method. Cambial activity in most trees began between May 12 and May 23, and ended between August 27 and September 10. Mean date of transition to latewood was July 6. In the treatment with the highest mean red alder basal area, Douglas- fir trees began radial growth later and ended earlier in the year than those in pure Douglas-fir stands. There was no evident effect of competition from red alder on the duration of cambial activity in treatments with intermediate to low red alder basal areas. In all treatments, the duration of radial growth was shorter in smaller-diameter trees. Early transition to latewood production was also associated with higher red alder basal area. Percent latewood was unaffected by treatment, but it was dependent on the date of a tree's transition to latewood production.

scholarly journals Pathogenicity and Virulence of Pythium Species Obtained from Forest Nursery Soils on Douglas-Fir Seedlings

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 744-748 ◽  
Author(s):  
Jerry E. Weiland ◽  
Bryan R. Beck ◽  
Anne Davis
Keyword(s):  
Pseudotsuga Menziesii ◽  
Seedling Survival ◽  
The United States ◽  
Douglas Fir ◽  
Tree Seedlings ◽  
Pythium Species ◽  
Forest Nursery ◽  
Damping Off ◽  
Greenhouse Study ◽  
Forest Nurseries

Pythium species are common soilborne oomycetes that occur in forest nursery soils throughout the United States. Numerous species have been described from nursery soils. However, with the exception of P. aphanidermatum, P. irregulare, P. sylvaticum, and P. ultimum, little is known about the potential for other Pythium species found in nursery soils to cause damping-off of tree seedlings. A greenhouse study was conducted to evaluate the pathogenicity and virulence of 44 Pythium isolates representing 16 species that were originally recovered from soil at three forest nurseries in Washington and Oregon. Seeds of Douglas-fir (Pseudotsuga menziesii) were planted into soil infested with each of the isolates. Seedling survival, the number of surviving seedlings with necrotic root lesions, and taproot length were evaluated 4 weeks later. Responses of Douglas-fir to inoculation varied significantly depending on Pythium species and isolate. Eight species (P. dissotocum, P. irregulare, P. aff. macrosporum, P. mamillatum, P. aff. oopapillum, P. rostratifingens, P. sylvaticum, and P. ultimum var. ultimum) significantly reduced the number of surviving seedlings compared to the noninoculated treatment. However, all Pythium species caused a greater percentage of seedlings to develop root lesions (total mean 40%) than was observed from noninoculated seedlings (17%). Taproot length varied little among Pythium treatments and was not a useful character for evaluating pathogenicity. Results confirm the ability of P. irregulare, P. mamillatum, and P. ultimum var. ultimum to cause damping-off of Douglas-fir seedlings, and are indicative that other species such as P. dissotocum, P. aff. macrosporum, P. aff. oopapillum, P. rostratifingens, and P. sylvaticum may also be responsible for seedling loss.

Cylindrocarpon and Fusarium root colonization of Douglas-fir seedlings from British Columbia reforestation sites

1998 ◽  
Vol 28 (8) ◽  
pp. 1198-1206 ◽  
Author(s):  
Paige E Axelrood ◽  
William K Chapman ◽  
Keith A Seifert ◽  
David B Trotter ◽  
Gwen Shrimpton
Keyword(s):  
British Columbia ◽  
Pseudotsuga Menziesii ◽  
Root Colonization ◽  
Linear Trend ◽  
Poor Performance ◽  
Douglas Fir ◽  
Root Infection ◽  
Significant Linear Trend ◽  
Conifer Seedlings ◽  
Cylindrocarpon Destructans

Poor performance of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) plantations established in 1987 has occurred in southwestern British Columbia. Affected sites were planted with 1-year-old container stock that exhibited some root dieback in the nursery. A study was initiated in 1991 to assess Cylindrocarpon and Fusarium root infection in planted and naturally regenerating (natural) Douglas-fir seedlings from seven affected plantations. Percentages of seedlings harboring Cylindrocarpon spp.and percent root colonization were significantly greater for planted seedlings compared with natural seedlings. A significant linear trend in Cylindrocarpon root colonization was observed for planted seedlings with colonization levels being highest for roots closest to the remnants of the root plug and decreasing at distances greater than 10cm from that region. This trend in Cylindrocarpon colonization was not observed for natural seedlings. Cylindrocarpon destructans (Zins.) Scholten var. destructans and C.cylindroides Wollenw. var. cylindroides were the only species isolated from planted and natural conifer seedlings. For most sites, percentage of seedlings harboring Fusarium spp.and percent Fusarium root colonization were less than for Cylindrocarpon. Recovery of Fusarium spp.from seedlings and root colonization levels were not significantly different for planted and natural seedlings from all sites.

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