Radiata Pine and Douglas Fir Timber Steel Encased Columns Subjected to Concentric and Eccentric Loading

2022 ◽  
Vol 148 (2) ◽  
Author(s):  
L. Kia ◽  
H. R. Valipour
Keyword(s):  
Radiata Pine ◽  
Douglas Fir

Characteristics of radio-frequency/vacuum combined with mechanical press drying of heavy softwood timbers with longitudinal kerf

Holzforschung ◽  
2021 ◽  
Vol 75 (1) ◽  
pp. 48-55
Author(s):  
Xuefeng Zhao ◽  
Changjin Lee
Keyword(s):  
Dielectric Permittivity ◽  
Temperature Gradient ◽  
Moisture Content ◽  
Radio Frequency ◽  
Radiata Pine ◽  
Douglas Fir ◽  
Fixed Frequency ◽  
Mechanical Press

AbstractThe aim of this study was to evaluate the characteristics of radio-frequency/vacuum combined with mechanical press (RF/VP) drying on three softwood timbers (Douglas fir, Hemlock, and Radiata pine) with longitudinal kerfs. The results were as follows: Due to the dielectric permittivity of wood, RF/VP drying at a fixed frequency of 13.56 MHz significantly influenced the moisture content (MC) distribution, the number of surface checks, shrinkage, and warp. These observations were attributed to the formation of a temperature gradient along the charge plate during the drying. The presence or absence of pith, more affected an occurrence of surface checks than that of the stresses within the wood during drying. The longitudinal kerf reduced the number of surface checks, but did not affect the MC distribution or the twist after drying.

Radial fissures in the early wood of conifers

1954 ◽  
Vol 2 (1) ◽  
pp. 22 ◽  
Author(s):  
GL Amos
Keyword(s):  
White Spruce ◽  
Radiata Pine ◽  
Wood Formation ◽  
Cellular Tissue ◽  
Douglas Fir ◽  
Free Access ◽  
Anatomy And Physiology ◽  
Ray Parenchyma ◽  
Ray Cells ◽  
Ray Parenchyma Cells

In certain conifers anatomical evidence suggests that young trees may become exposed to conditions conducive to collapse during late wood formation, causing partial collapse and radial cleavages in the early wood. Living ray cells are exposed to the cavity after cleavage. Different species show different responses conditioned by the anatomy and physiology of the ray parenchyma. The cavities fill with cellular tissue in radiata pine (Pinus radiata D. Don), with resin in Douglas fir (Pseudotsuga tarcifolia (Poir.) Britt.), and remain empty in white spruce (Picea glauoa (Moench) Voss). Evidence is presented to show that when a living protoplast is given free access to moist air, a powerful growth stimulus is applied to the cell. In radiata pine, ray parenchyma cells have primary walls only, and the response is a proliferation of these cells. In Douglas fir and white spruce, the ray parenchyma has secondary thickening and small ray tracheid pitting, precluding growth. The response is an increased metabolic rate, producing resin in Douglas fir (heartwood-forming species) and without solid end-products in white spruce (species with little contrast between sapwood and heartwood).

scholarly journals Phytophthora pluvialis Studies on Douglas-fir Require Swiss Needle Cast Suppression

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1259-1262 ◽  
Author(s):  
Mireia Gómez-Gallego ◽  
Martin Karl-Friedrich Bader ◽  
Peter Matthew Scott ◽  
Sebastian Leuzinger ◽  
Nari Michelle Williams
Keyword(s):  
New Zealand ◽  
Pacific Northwest ◽  
Radiata Pine ◽  
Douglas Fir ◽  
Needle Cast ◽  
The Pacific ◽  
Swiss Needle Cast ◽  
Phytophthora Pluvialis ◽  
Red Needle Cast ◽  
Ubiquitous Presence

Phytophthora pluvialis is associated with early defoliation and shoot dieback in Douglas-fir in Oregon and New Zealand. In 2013, P. pluvialis was described from mixed tanoak-Douglas-fir forests in the Pacific Northwest and concurrently recognized as the main causal agent of red needle cast (RNC) in New Zealand radiata pine plantations. Little is known about its infection cycle and impact on host physiology. P. pluvialis studies in Douglas-fir are challenging due to the ubiquitous presence of the endophyte Phaeocryptopus gaeumannii, which produces similar symptoms and premature defoliation with persistent needle wetness, known as Swiss needle cast (SNC). Nonetheless, our study showed P. pluvialis infection in the presence of SNC. Exclusive expression of P. pluvialis is difficult to achieve as both diseases are promoted by high humidity. Here we established a ‘dry leaf’ strategy to suppress SNC when inoculating Douglas-fir needles for RNC studies. Sheltering plants along with drip irrigation to avoid needle wetness during the P. gaeumannii sporulation period suppressed its development in the new season flush. The diminished endophyte inoculum enabled bias-reduced studies of P. pluvialis impacts on Douglas-fir without the confounding effects of stomatal blockage and premature defoliation caused by P. gaeumannii.

scholarly journals Farm forestry for economic and environmental sustainability - A new decision support system for farm foresters

2003 ◽  
Vol 10 ◽  
pp. 85-90
Author(s):  
M.M. Halliday ◽  
R.L. Knowles
Keyword(s):  
Decision Support ◽  
Root Biomass ◽  
Radiata Pine ◽  
Douglas Fir ◽  
Critical Threshold ◽  
Farm Forestry ◽  
Gross Margin ◽  
Financial Return ◽  
Tree Crops ◽  
Pastoral Farming

The objective of this programme is to provide farm foresters and others with knowledge about sustainable and profitable land use with commercial tree crops. Initially the study examined the role of trees in stabilising soils when planted on eroding hill country pasture. Three species - radiata pine, Douglas-fir, and poplar - were compared for effects in reducing erosion. Tree size, tree stocking per hectare, root tensile strength, and rate of decay of roots after harvest were found to be important. Erosion control becomes effective once a stand of trees reached the equivalent of 30 tonnes/ha of radiata pine root biomass. Silviculture, and choice of species, determines to what extent this critical threshold is achieved. Decision support software, developed in this programme as "calculators', estimate the 'Equivalent Farming Gross Margin' of crops of radiata pine, and Douglas-fir, compared to the livestock previously grazing the land. The calculators, which run under Microsoft EXCELTM, also allow the identification of the most profitable silviculture for the tree crop, and generate yield tables. The calculators are being applied in two case studies; the first involves calibrating the radiata pine calculator for Hawkes Bay and the Wairarapa against actual tree data. Calibration of the calculator for bare land is also being studied. The second study will investigate how well tree crops can compete financially with pastoral farming systems in the Lake Taupo catchment, where there are increasing concerns about nutrient in-flows from pastoral farming. Further enhancements of the calculators are planned which will permit calibration against younger stands, and evaluation of a much wider range of silviculture. Keywords: farm forestry, erosion, root biomass, root strength, financial return, IRR, PNW, farming gross margin, Pinus radiata, Douglas-fir, poplar

scholarly journals Alternative tree species on farms

2003 ◽  
Vol 10 ◽  
pp. 91-101
Author(s):  
J.D. Hocking
Keyword(s):  
New Zealand ◽  
Tree Species ◽  
Radiata Pine ◽  
Douglas Fir ◽  
Sequoia Sempervirens ◽  
Acacia Melanoxylon ◽  
Sequoiadendron Giganteum ◽  
Populus Spp ◽  
End Uses

The more commonly and successfully grown species of timber trees, grown in New Zealand as alternatives to radiata pine, are briefly reviewed, with emphasis on site requirements and timber end uses. Their silviculture and marketing is considered. The groups covered are Douglas Fir (Pseudotsuga menzesii), the cypresses (Cupressus species and hybrids), eucalypts (Eucalyptus spp.), acacias (Acacia melanoxylon and some others) and more briefly redwood (Sequoia sempervirens and Sequoiadendron giganteum) and poplars (Populus spp.).

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