Small Diameter Logs Research Articles

Transverse Vibration of a Simply Supported Frustum of a Right Circular Cone

Abstract Presently, there is no efficient mechanical method in the United States to sort small-diameter logs. This paper explores the problem theoretically using transverse vibration as one such method. The numerical solution to the frequency equation for the transverse vibration of a simply-supported frustum of a right circular cone is found. We refer to this solid as a tapered cylinder with constant taper. The numerical solution is found as a function of cylinder taper, and an approximation to the solution of the frequency equation for slight taper is presented and compared with the numerical solution. This simple yet accurate approximation is most useful to determine the tapered cylinder's flexural stiffness or modulus of elasticity by freely vibrating a simply supported tapered cylinder.

Nutrient uptake and immobilization in a short-rotation coppice stand of hybrid poplars in north-west France

Biomass and nutrient uptake were estimated, at harvest, in a short-rotation coppice plot of hybrid poplars ( Populus trichocarpa × deltoides) monitored from planting. Soil reserves and restitutions by litterfall were also studied. For the two clones studied ( cv ` Beaupré' and ` Raspalje'), total above-ground biomass reaches 88.8 and 74.7 t ha −1 dry matter, respectively. Annual nutrient uptakes reached 92, 15 and 87 kg ha −1, respectively, for N, P and K, for the most productive clone ( cv ` Beaupré'). About 60–80% of this uptake returns to the soil each year through litterfall. Litterfall reaches 4–5 t ha −1 year −1 at age 7 or 8. Nutrient removal is estimated in relationship to the type of harvesting (logs or total biomass). Results for the coppices under study were very high compared to those of standard coppices. Restitution by fertilization was evaluated. Whole tree harvesting increases harvested biomass by 30%, but also increases N removal by 84%. Harvest of 7 cm small end diameter logs provides the best compromise between yield and nutrient exports.

Poplar agroforestry in India

The development of poplar agroforestry and associated research in India is reviewed. The model of agroforestry development involving a partnership between farmers, the private sector and the government is worthy of further investigation for application in other areas of India and to other countries. A number of suggestions are given for further research in the context of optimising the system for resource-poor farmers. These include changes in tree and crop varieties, tree spacing, and utilisation of small diameter logs, and other poplar products.

Ind

The investigation of three concessionaires in Kalimantan practicing the trial of Indonesian Strip Cutting and Planting System was conducted in 1994. All the companies are in the early stage of the trial and, therefore, the focus of investigation is limited to trial preparation and timber harvesting with the aim of describing the real practices and various problems faced in the field. It is found that the productivity of each activity in preparation and timber harvesting in the Indonesian Strip Curing and Planting System (A) is lower than those in the Indonesian Selective Cutting and Planting System (B). The comparison of several productivities are as follows : (I) Felling: 47 cu. m/day forA and 85 cu. m/day for B: (2) Skidding : 37 cu.m/day for A and 85 cu.m/day for B; (3) Loading-unloading : 55 cu.m/day for A and 150 cu.m/day for B; (4) Hauling :. 50 cu.m/trip forA and 64 cu.m/trip for B. The above figures and observation in the field lead to the notion of several problems faced such as : (1) in matching the required strip direction and real field condition ; (3) improper skill of workers; (4) unsuitable wage system; (5) inability to utilize the small diameter logs; (6) too large cable used for skidding; (7) too large log clamp available on loader tractor: (8) difficulty in handling small diameter logs onto logging truck; and (9) high percentage of land area disturbed due to large equipment and strip width limitation. The trial is still in the early stage and the information is very limited and therefore, further investigations is strongly recommended to cover more locations and aspects so that the final results can be used by the authority to make sound conclusions in selecting the final arrangement of the Indonesian Strip Cutting and Planting System.

Coarse woody debris and forest floor respiration in an old-growth coniferous forest on the Olympic Peninsula, Washington, USA

Carbon dioxide evolution rates for downed logs (coarse woody debris) and the forest floor were measured in a temperate, old-growth rain forest in Olympic National Park, Washington, using the soda lime trap method. Measurements were taken every 4 weeks from October 22, 1991, to November 19, 1992. Respiration rates for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and western hemlock (Tsugaheterophylla (Raf.) Sarg.), logs were determined for decay classes 1–2, 3, and 5 in two diameter classes. Overall, western hemlock logs respired at a rate 35% higher (4.37 g CO2•m−2•day−1) than Douglas-fir logs (3.23 g CO2•m−2•day−1). Respiration rates for decay class 1–2 logs of both species were similar to decay class 5 logs (4.46 and 4.07 g CO2•m−2•day−1, respectively), but decay class 3 logs respired at a lower rate (3.23 g CO2•m−2•day−1). Seasonal patterns of respiration rates occurred, particularly for decay class 1 and 2 western hemlock logs where monthly averages ranged from a low of 2.67 g CO2•m−2•day−1 in February 1992 to a high of 8.30 g CO2•m−2•day−1 in September 1992. Rates for decay class 1–2 western hemlock logs were greater than those from the forest floor, which ranged from 3.42 to 7.13 g CO2•m−2•day−1. Respiration rates were depressed in late July and August compared with fall and spring owing to the summer drought characteristic of the Pacific Northwest. Large-diameter western hemlock logs in decay class 1–2 had higher respiration rates than small-diameter logs, whereas large-diameter decay class 3 western hemlock logs had lower respiration rates than small-diameter logs.

"Black Bark" Ponderosa Pine: Tree Grade Definition and Value Comparison with Old-Growth Trees

Abstract A ponderosa pine (Pinus ponderosa) tree grade has been developed to separate lower value, small-diameter trees typical of young-growth stands from small-diameter old-growth trees. The tree grade uses a combination of bark, limb, and crown characteristics to identify the "black bark," trees. The tree grade was tested in two shop type mills and one dimension mill in southern Oregon and eastern Washington. Significant differences in value were found between the sample of black bark pine and the grade 5 control sample. Differences in value increased with diameter because of increased opportunities to recover high-quality lumber from the larger old-growth trees. The dimension mill recovered more lumber volume from the smaller diameter logs because of fewer sawlines and smaller rough-green sizes. Even though the shop mills recovered lower volumes, they did recover higher value by producing Shop and Common grade lumber rather than standard Dimension grades. Overall the differences compensated for each other, and both mill types recovered roughly equal value from logs of similar grade and size. West. J. Appl. For. 9(1): 8-13.

防腐小径木の木レンガ歩道への利用

防腐小径木の木レンガ歩道への利用

The role of the Douglas-fir beetle and wood borers in the decomposition of and nutrient release from Douglas-fir logs

The role of insects in the decomposition of and nutrient release from Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) logs was studied in the Cedar River Watershed near Seattle, Washington. In April 1976, two large-diameter (average diameter at breast height, 41.7 cm) and two small-diameter (average diameter at breast height 26.3 cm) trees were felled. Three pairs of 91 cm length sections were cut from each tree. Half the sections were covered with window screening to prevent insect entry. The number of Douglas-fir beetle (Dendroctonuspseudotsugae Hpk.) attacks on each section, as well as the frass production, were monitored. After 10 years, decomposition rates were determined by mass loss. Douglas-fir beetles attacked large-diameter (23 attacks/m2) and small-diameter (27 attacks/m2) log sections at similar rates. Total frass production was also similar (33.6 g•m−2 for large logs and 32.6 g•m−2 for small logs). Large-diameter unscreened log sections tended to decompose faster (k = 0.050 per year) than small diameter unscreened logs (k = 0.026 per year) owing to the presence of wood borers (Monochamusscutellatus (Say)) in the larger logs. Screening of logs to reduce insect attack tended to reduce the rate of decomposition. A brown rotting fungus (Oligoporusplacentus (Fr.) Gilb. and Ryv.) fruited on unscreened large-diameter logs. Wood borers had a greater influence on log decomposition than Douglas-fir beetles. Frass produced by the Douglas-fir beetle contributed very little to litter fall and nutrient cycling. After 10 years there was a net release of N, P, K, Ca, and Mn from decomposing logs. Only Mg was immobilized in large-diameter logs.

The influence of defects on the utilization of small diameter logs

The influence of defects on the utilization of small diameter logs

The influence of defects on the utilization of small diameter logs

The influence of defects on the utilization of small diameter logs

Wood generated by thinning in the northern jarrah forest

Summary For regrowth stands in the northern jarrah (Eucalpytus marginata) forests of Western Australia, a study was undertaken of the amount of wood, not commercial under current standards, that would be produced if the stands were thinned as a silvicultural treatment. Trees greater than 15 cm dbhob along strip lines were assessed for a range of wood products, and then selected for retention to give either 10%, 20% or 30% canopy cover (the original canopy cover was 55%). The study area was then actually thinned to leave a 20% canopy cover, which yielded 90 m3/ha of currently unsaleable bole wood, though two thirds of the jarrah conponent of this was assessed as potentially unable, most of it being of good quality but under the currently accepted minimum log diamenter of 50 cm. The use of these small diameter logs is therefore a major problem to which research should be directed. The benefits of silvicultural treatment of the forest are discussed.