scholarly journals Are 40 years better than 55? An analysis of the reduction of forest rotation to cope with drought events in a Douglas fir stand

2019 ◽  
Vol 76 (2) ◽  
Author(s):  
Nathalie Bréda ◽  
Marielle Brunette
Keyword(s):  
Douglas Fir ◽  
Forest Rotation ◽  
Better Than

Aboveground Field Performance of Douglas-Fir Heartwood Subjected to Combinations of Glycerol, Boron, and Thermal Modification

2021 ◽  
Vol 71 (1) ◽  
pp. 42-45
Author(s):  
Li Yan ◽  
Jed Cappallazzi ◽  
Jeffrey J. Morrell
Keyword(s):  
Field Performance ◽  
Decay Resistance ◽  
Douglas Fir ◽  
Thermal Modification ◽  
Site Conditions ◽  
Consistent Effect ◽  
Wood Protection ◽  
Copper Azole ◽  
Better Than

Abstract The effect of pretreatment with either boron or glycerol followed by thermal modification on the durability of Douglas-fir heartwood was evaluated in an American Wood Protection Association ground proximity test in Hilo, Hawaii. Non–thermally modified samples were generally more heavily decayed than any of the modified woods, but there was no consistent effect of different thermal modification conditions on decay resistance. Thermally modified woods tended to perform better than untreated timbers but not as well as copper azole–treated Douglas-fir heartwood lumber in test at the same site. The results are discussed in relation to how the extreme site conditions might have made it difficult for thermally modified materials to perform.

Early Development of Three Douglas-Fir Stocktypes on a Droughty Skeletal Soil

1989 ◽  
Vol 4 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Stephen D. Hobbs ◽  
Michael S. Crawford ◽  
Beverly A. Yelczyn
Keyword(s):  
Surface Soil ◽  
Morphological Characteristics ◽  
Field Performance ◽  
Douglas Fir ◽  
Root Characteristics ◽  
Relative Growth ◽  
Seedling Root ◽  
Absolute Growth ◽  
Southwest Oregon ◽  
Better Than

Abstract Three stocktypes of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) were planted in a droughty, skeletal soil in southwest Oregon. After 5 years, container-grown plugs and plug-1 transplants survived significantly better than 2-0 bareroots. Seedling root systems were largely confined to the surface soil, with relatively little development upslope or deeper than 15 cm. Stocktype morphology differed significantly at planting. However, annual absolute growth, annual relative growth, and shoot and root characteristics did not differ significantly after 5 years. These results suggest that, on similar sites, seedling morphological characteristics within the range of those measured in this study may not affect growth and that stocktype designation along may not be adequate for predicting field performance. West. J. Appl. For. 4(1):21-24, January 1989.

scholarly journals 567 PB 006 AUXIN SENSITIVITY OF DOUGLAS-FIR STEM CUTTINGS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 513a-513
Author(s):  
William M. Proebsting
Keyword(s):  
Douglas Fir ◽  
The Other ◽  
Tree Plantations ◽  
Christmas Tree ◽  
Stem Cuttings ◽  
Wide Range ◽  
Better Than

Douglas-fir clones have a wide range of rooting potential, but the species is generally considered difficult to root. We have reported previously that NAA is approximately 14-times more active than IBA in the clones tested, with an optimum of about 5 to 10 mM NAA. In contrast, other programs routinely use about 25 mM IBA to propagate Douglas-fir cuttings, a concentration that is relatively inactive in our clones. To address questions raised by these observations, we have incorporated auxin treatments into our long term program to select Douglas-fir clones with high rooting potential. We collect 20 cuttings of each clone identified in Christmas tree plantations, and retain clones rooting ≥ 80%. Beginning in 1991, we treated 10 cuttings of each clone with 5 mM NAA, the other 10 cuttings with 25 mM IBA. Over three years, 1158 clones received the split treatments. Of 222 clones rooting ≥ 80%) approximately half rooted ≥ 80% in response to NAA only. The remainder either responded to IBA or to both NAA and IBA. These results support our previous observations that NAA stimulates rooting of Douglas-fir better than IBA. However, they also suggest that there may be clones sensitive to IBA or to both NAA and IBA.

Foliage distribution in old-growth coniferous tree canopies

1982 ◽  
Vol 12 (1) ◽  
pp. 10-17 ◽  
Author(s):  
W. J. Massman
Keyword(s):  
Normal Distribution ◽  
Beta Distribution ◽  
Tree Height ◽  
Douglas Fir ◽  
Old Growth ◽  
Chi Square ◽  
Sugar Pine ◽  
Tree Canopies ◽  
The Vertical Distribution ◽  
Better Than

The vertical distribution of foliage for several old-growth trees is discussed and modeled. The data include the foliage distribution of nine Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) crowns, the foliage distribution of a sugar pine (Pinuslambertiana Dougl.) crown, and the foliage distribution of a composite of the nine Douglas-fir trees which represents the stand canopy. The data show that the foliage is distributed asymmetrically in the crown with the maximum amount often located at a height approximately equal to 80% of the tree height. The data further show that the crown base is 9–30 m above the ground. Five different mathematical models of the foliage distribution (a normal distribution, a chi-square distribution, a beta distribution, a difference of exponentials, and a chi-square-like distribution) are fitted to the data and compared. The beta distribution and the chi-square distribution appear to fit the data slightly better than the others; but the differences in r2 between all the models are often small. The normal distribution has the advantage that it shows the least variability from one tree to the next; however, it also has the disadvantage that it is significantly different from zero at the top of all the tree crowns modeled here.

Partitioning heterotrophic and rhizospheric soil respiration in a mature Douglas-fir (Pseudotsuga menziesii) forest

2007 ◽  
Vol 37 (8) ◽  
pp. 1287-1297 ◽  
Author(s):  
Rachelle G. Lalonde ◽  
Cindy E. Prescott
Keyword(s):  
Pseudotsuga Menziesii ◽  
Lateral Diffusion ◽  
Douglas Fir ◽  
Rhizospheric Soil ◽  
Sources Of Error ◽  
Nylon Mesh ◽  
Potential Sources ◽  
Belowground Respiration ◽  
Root Exclusion ◽  
Better Than

Total belowground respiration (Rs) was partitioned into heterotrophic (Rh) and rhizospheric (Rr) respiration to determine the amount of CO2 originating from each component in a coastal Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) forest. Rh was measured within cylinders from which roots, hyphae, and associated rhizosphere organisms were excluded by a 0.5 μm nylon mesh and installed 50 cm into the soil. Rs was 12 Mg C·ha–1·year–1 and ranged from 0.71 to 6.57 g C·m–2·day–1 during the 15 month experiment. Rh was 7.8 Mg C·ha–1·year–1, which contributed 65% of Rs, mostly between May and August. Rr was 4.2 Mg C·ha–1·year–1 (35% of Rs) and peaked in spring and fall. Soil temperature described the variability in Rs (p = 0.0004) better than soil moisture (p = 0.6156) and Rh was more closely related to temperature than was Rr. Values of Q10 were 1.7 for Rs and 2.2 for Rh. We also assessed three potential sources of error associated with this root-exclusion technique: respiration from decaying severed roots, stimulated respiration as a result of cylinder installation, and lateral diffusion of CO2 into cylinders. None of these artifacts were found to be significant sources of error in this experiment.

scholarly journals Geographic Variation and Local Growth Superiority for Coastal Douglas-fir – Rotation-age Growth Performance in a Douglas-fir Provenance Test

2014 ◽  
Vol 63 (1-6) ◽  
pp. 116-124
Author(s):  
Terrance Z. Ye ◽  
K. J. S. Jayawickrama
Keyword(s):  
Growth Performance ◽  
Geographic Distance ◽  
Volume Growth ◽  
High Elevation ◽  
Mantel Test ◽  
Douglas Fir ◽  
Local Growth ◽  
Provenance Test ◽  
Rotation Age ◽  
Better Than

Abstract Rotation-age growth performance of 16 provenances and local growth superiority were assessed from a rotation- age reciprocal coastal Douglas-fir [Pseudotsuga menziesii var. menziesii (Mirb.) Franco] provenance test established in the Pacific Northwest of America. Provenance differences for total volume per plot were highly significant. Due to the significant provenance × site interaction effect, the best provenances varied across planting sites in terms of rotation-age volume growth. Local provenance trees exhibited superior volume growth at two of the six planting sites. At the remaining four sites, local provenances performed equally well as average non-local provenances. At the three low-elevation (< 460 m) sites, low-elevation provenances performed significantly better than high-elevation provenances. By contrast, high- and low-elevation provenances had similar growth at the two high-elevation (> 800 m) sites. Southern provenances generally grew faster than northern provenances at the Oregon sites, while northern provenances performed better than southern provenances at the sites in British Columbia. Regression analyses showed that although local growth superiority increased with the geographic distance between provenance’s origin and the test site in general (r=0.47, P<0.001), it only became obvious when the geographic distance is larger than 435 km in latitude or 370 m in elevation. Significant spatial autocorrelation was found via Mantel test, and geographically or climatically closely located provenances tended to have similar rotation-age volume growth. The results suggested that breeding zones larger than the current second-cycle zones would lead to little loss of rotation-age total volume for coastal Douglas-fir in this region.

Field performance of Douglas-fir seedlings after treatment with fungicides

1986 ◽  
Vol 16 (6) ◽  
pp. 1369-1371
Author(s):  
Peyton W. Owston ◽  
Walter G. Thies ◽  
William Fender
Keyword(s):  
Similar Condition ◽  
Field Performance ◽  
Douglas Fir ◽  
Cascade Range ◽  
Seedling Height ◽  
Fungicide Treatment ◽  
Potting Medium ◽  
Carry Over ◽  
Mycorrhizal Development ◽  
Better Than

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings grown in containers with pasteurized or nonpasteurized potting mixture and treated with benomyl, captan, fenaminosulf, or ethazol, or left untreated were outplanted in the Cascade Range of western Oregon. The seedlings from all treatments appeared to have been in similar condition at time of planting, so neither nursery managers nor silviculturists would have suspected effects of the treatments to carry over to field performance. After 7 years, however, seedlings grown in pasteurized potting medium survived better than those grown in nonpasteurized medium. Furthermore, survival of benomyl-treated seedlings in pasteurized potting mixture was higher than survival of those grown in pasteurized mixture without any fungicide treatment and survival of ethazol-treated seedlings in unpasteurized mixture was lower than those in unpasteurized mixture without fungicide treatment. There was no evidence that the nursery treatments adversely affected seedling height or mycorrhizal development.

Survival and Growth of Ponderosa Pine and Douglas-Fir Stocktypes on a Dry Low-Elevation Site in Southwest Oregon

1989 ◽  
Vol 4 (4) ◽  
pp. 124-128 ◽  
Author(s):  
Ole T. Helgerson ◽  
Steven D. Tesch ◽  
Stephen D. Hobbs ◽  
D. H. McNabb
Keyword(s):  
Weed Control ◽  
Pseudotsuga Menziesii ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Douglas Fir ◽  
Growing Seasons ◽  
Survival And Growth ◽  
Southwest Oregon ◽  
Better Than

Abstract Two stocktypes (1 + 0 container-grown plugs and 2 + 0 nursery grown bareroots) of ponderosa pine (Pinus ponderosa) and of Douglas-Fir (Pseudotsuga menziesii) were planted on a hot, droughty, low-elevation site in southwest Oregon (Interior Valley Zone) to assess the potential for reforesting this type of site. After five growing seasons, bareroots survived (98%) significantly (P < 0.05) better than plugs (89%); survival did not differ significantly by species. Douglas-fir was taller than pine, pine was larger in diameter, and the two species had approximately equal stem volumes. Bareroots were consistently larger than plugs. These species and stocktypes can provide good reforestation after 5 years on an Interior Valley Zone site when seedlings are of good quality, are planted properly, and are given good weed control. West. J. Appl. For. 4(4):124-128, October 1989.

Effects of long-term pruning, meristem origin, and branch order on the rooting of Douglas-fir stem cuttings

1992 ◽  
Vol 22 (12) ◽  
pp. 1888-1894 ◽  
Author(s):  
Donald L. Copes
Keyword(s):  
Flat Surface ◽  
Tree Height ◽  
Douglas Fir ◽  
Second Order ◽  
Stem Cuttings ◽  
First Order ◽  
Secondary Origin ◽  
Rooting Of Cuttings ◽  
Better Than

The rooting percentages of 14 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) clones were examined annually from 1974 to 1988. The trees were 10 and 13 years old in 1974 and were pruned to 2.0 m in 1978 and 1979 and then recut annually to 0.5, 1.0, or 1.5 m, starting in 1983. The pruned trees showed no evidence of decreased rooting percentage even after 15 years; average rooting increased from 47% in 1974 to 74% in 1986. Rooting percentage was significantly influenced by tree height. Cuttings collected from 0.5 m tall ramets exhibited better rooting than cuttings from 1.0 or 2.0 m tall ramets, and cuttings from 1.0 m tall ramets rooted better than cuttings from 2.0 m tall ramets. Rooting of cuttings collected from 0.5 m high subinterval zones within trees showed a negative linear relation between rooting percentage and collection height. Cuttings collected from the 0–0.5 m zone rooted 25% better than cuttings from the 1.5–2.0 m zone of the 2 m tall trees. That difference was significant at p < 0.05. A test of rooting of larger, more orthotropic cuttings gathered from the upper flat surface of pruned ramets indicated that the cuttings from the top rooted significantly less than smaller, more plagiotropic cuttings from the contiguous side areas (24 versus 33%, respectively). Rooting comparisons of meristems of primary and secondary origin showed significantly greater rooting of secondary meristems. Comparison of rooting of second-order and first-order meristems of secondary origin indicated the second-order twigs averaged 26% better rooting than the first-order branch tips when the cuttings were collected in January and placed in the rooting beds in February.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

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