Productivity and Costs of Three Harvesting Methods
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Abstract Three stands were harvested by either clearcut, shelterwood, or single-tree selection methods. The single-tree selection method consisted of a light thinning in an even-aged stand as the initial basal area reduction cut required to convert the stand to uneven-aged structure. The contractor used two skidders (one grapple, one choker) and production chain saws to harvest all three tracts. Harvested sites were all similar in slope (10-15%), average dbh (12-14 in.), and preharvest number of stems by dbh. In the felling study, fell, walk, and limb-top time were all greater for the single-tree selection method. Time to process a tree was lowest for the clearcut, intermediate for shelterwood, and highest for single-tree selection method. For skidding, bunch building time was highest for the single-tree selection and lowest for the clearcut method. Average volume per cycle was consistently higher for the grapple skidder than the choker skidder; volume per cycle was lowest for the single-tree selection and highest for the clearcut method for both skidders. Time per cycle was consistently lower for the grapple skidder than the cable skidder. Time per cycle was lowest for the clearcut and highest for the single-tree selection method. Factors that affected felling productivity (in decreasing order) were: dbh of harvested stems, intertree distance, and method of harvest. Factors that affected skidding productivity (in decreasing order) were: skidder type, pull distance, average volume per cycle, and the method of harvest. Costs of felling and skidding were highest on the single-selection stand and lowest on the clearcut stand. Total percentage of stand area trafficked was lowest for the single tree stand. However, the total area disturbed to meet a wood procurement budget was lowest for the clearcut and highest for the single-tree method. South. J. Appl. For. 18(4): 168-174.Keywords:
Felling
Basal area
Thinning
SUMMARY In a replicated trial near Canberra, first thinnings of a 16-year-old plantation of radiata pine (Pinus radiata D. Don) were carried out by felling every second row (R2), felling every third row (R3), felling every fifth row plus individually selected trees in intermediate rows (SR), and felling only individually selected trees (S). The trees individually selected for felling were those of poorest vigour or form. At the time of thinning, the stands had, on average, a predominant height of 22.3 m and a basal area of 41.7 m2/ha before thinning and 20.4, 27.9, 24.1 and 24.5 m2/ha after the R2, R3, SR and S thinnings, respectively. There was no significant difference in growth between the R2 and R3 treatments or between the SR and S treatments. During the six years after thinning the overall growth in volume of the row thinned plots (R2 and R3) was estimated to be 17 per cent less than that of the selectively thinned plots (SR and S). This lower growth was due to the retention on the row thinned plots of a larger proportion of small trees which grew less (in per cent of their basal area) than the larger trees. However, the growth of the 250 largest diameter stems per hectare did not vary with treatment. There was no evidence that the form of the trees remaining after thinning was adversely affected by row thinning. The indications are that earlier thinnings would have caused less difference between the growth of row thinned stands and that of selectively thinned stands.
Thinning
Felling
Basal area
Pinus radiata
Radiata
Hectare
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The objective of this study was to evaluate the damage to remaining trees of pine stand submitted to two models of mechanized thinning. Data were collected in the wood harvesting areas of a forest company in Southern Brazil during the first commercial thinning with 10-year-old trees. The thinning was executed by a harvester in cutting the trees and a forwarder in extracting the logs, which was defined by thinning in the 5th planting line (treatment T1); and by a chainsaw in felling the central trees, by a harvester in cutting the other lines, and by a forwarder in extracting the logs in the experimental area defined by thinning in the 7th planting line (treatment T2). The damage to remaining trees in the stand in relation to the dimensions and location of the machinery operating trail was evaluated, and data were analyzed through descriptive statistics. The results showed that treatment T2 caused greater damage in the remaining trees due to greater handling of felled and processed trees and a higher concentration of wood piles in the operating trail of the machines. In addition, there was greater contact of the harvester with the remaining trees when searching for the trees felled by the chainsaw was conducted to perform the final processing. Treatment T1 proved to be more suitable for thinning pine stands.
Thinning
Felling
Forwarder
Silviculture
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In Italy, some silvicultural treatment as thinning could be carried out in an economic way adopting systems based on small-scale mechanization. This paper examines the productivity standards of wood biomass in coniferous plantation thinning in Southern Italy under the conditions of small-scale forestry. The objectives of the study were to evaluate the incidence of different silvicultural treatments on productivity and harvesting costs and create productivity models for typical harvesting system used for wood thinned from Calabrian pine. Three different sites were monitored on the Sila Massif forest, and the experimental plan included three area tests, subjected in the last thirty years to intermediate cuttings with different thinning grade: light thinning (A thesis), moderate thinning (B thesis), heavy thinning (C thesis). The authors developed a productivity model for motor-manual felling and skidding timber with wheeled farm tractors, equipped with winch using a time motion study. Whole tree extraction system in coniferous plantation applied with typical felling system traditional has guaranteed productivity standards at a reasonable cost reducing high operational cost per unit harvested. The results, therefore, underlined that it economic possible to wood biomass harvest relatively small-diameter from thinning stands favoring moderate and heavy thinning.
Thinning
Felling
Silviculture
Mechanization
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Experimental plots were established for thinning effects on the total basal area and total yield of stand in three forest types,Pinus koraiensis plantation, natural secondary Quercus mongolica forest and artificially inducing broad-leaved Pinus koraiensis forest in eastern mountainous region of Liaoning province by using several decades` observation data. The results showed that thinning could not improve the total increment of stand basal area and stand volume in Pinus koraiennsis plantation, but over-high intensity and high intensity thinning could improve the growth rate of stand basal area. With the increase of thinning intensity, the total stand basal area in Pinus koraiensis plantation first increased, and then decreased.All thinning intensity could improve the total stand basal area in Pinus koraiensisplantation,exceptover-high intensity.All thinning intensity could improve the growth rates of stand volume in Pinus koraiensis plantation, except low intensity. With the increase of thinning intensity, the total yield of Pinus koraiensis plantation first increased,and then decreased. All thinning could improve the total yield of Pinus koraiensis plantation, medium intensity is the best. Thinning could improve the total increment and the growth rate of stand basal area and stand volume in natural secondary Quercus mongolica forest. Thinning could improve the total stand basal area and the total yield of natural secondary Quercusmongolica forest. With the increase of thinning intensity, all indexes of secondary Quercus mongolica forest first increased, and then decreased, medium intensity is the best. Thinning could improve the total increment and the growth rate of stand basal area and stand volume in artificially inducing broad-leaved Pinus koraiensis forest. Thinning could improve the total stand basal area and the total yield of artificially inducing broad-leaved Pinus koraiensis forest. With the increase of thinning intensity,the total increment of stand basal area and stand volume, the total stand basal area and the total yield increased. With the increase of thinning intensity, the growth rate of stand basal area and stand volume first increased, and then decreased, high intensity is the best. Therefore reasonable thinning intensity could improve the total stand basal area and the total yield of forest.
Thinning
Basal area
Pinus koraiensis
Intensity
Natural forest
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Abstract A growing interest in the restoration of young second-growth forests by managers of reserves in the redwood region has led to a need to evaluate restoration-based silvicultural strategies. This case study assessed the effectiveness of low thinning as a forest restoration tool via analysis of stand structure at Redwood National Park's Whiskey Forty Forest Restoration Study. The second-growth stand had more than 5,500 trees ha−1 and 57.0 m2 ha−1 basal area and consisted chiefly of three species: Douglas-fir (the dominant species), redwood, and tanoak. Low thinning reduced stand density but also reduced species richness by eliminating scarce species. Seven years after thinning, growth was enhanced (33.6% gain in basal area), and mortality was minor (3% of all stems); however, Douglas-fir remained competitive in the upper canopy. Its average basal area increment was less than redwood's, but its radial growth was equal and its rate of basal area growth was greater in the years following thinning. We conclude that the thinning improved stand conditions but did not fully satisfy restoration goals and that other thinning methods, such as variable-density thinning, are likely to be more effective at promoting redwood dominance.
Thinning
Basal area
Dominance (genetics)
Stand development
Silviculture
Restoration Ecology
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Concern has risen about the degree to which Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands with severe infections of Swiss needle cast (SNC) respond to thinning. A retrospective study was established in the fall of 2001 to assess the growth of Douglas-fir stands that were commercially thinned between 4 and 10 years ago. Current SNC infection levels in these stands ranged from severe to very light. Past volume and basal area growth declined with increasing severity of SNC, as measured by current foliage retention and crown length / sapwood ratio. As has been observed in many other studies, thinning to lower residual stock reduced stand level growth; however, individual tree growth increased with lower residual stand density. The ratio of growth in successive periods and analysis of annual basal area growth since thinning suggested that trees did respond to thinning, although less so as SNC increased. A positive response to thinning, regardless of infection level, was confirmed by an analysis of annual trends in basal area growth over the first 5 years after thinning.
Thinning
Basal area
Douglas fir
Annual growth %
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Thinning
Felling
Scots pine
Silviculture
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A Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) thinning study was established in 1959 in a stand begun after logging in 1930. Thinnings to set basal area densities were done in 1959, 1962, 1966, and 1970. On each plot both large and small trees were removed since average basal area per tree was kept constant before and after thinning. Volume growth varied greatly between plots of the same age, initial basal area, and site because of differences in stand structure. Large trees on a plot grew more per tree and per basal area than small trees. Stand basal area, stand volume, number of stems, or number of dominant and codominant trees were not closely related to volume growth per hectare, although density indexes giving weight to larger trees showed the closest relation. The lack of close relation between stand density indexes and growth found here and elsewhere probably means the indexes do not uniquely define stand structures; it does not necessarily mean that thinning will not increase volume growth per hectare. Volume growth per hectare after thinning to a given basal area density will be greater and probably more consistent if larger trees are left and enough time is allowed for the stand to recover following thinning.
Thinning
Basal area
Hectare
Site index
Douglas fir
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Summary A 24-y-old stand of Eucalyptus regnans (F.Muell.) in the Plenty Valley, Tasmania was thinned to residual basal areas of about 14, 21 and 28 m2 ha−1, representing basal area reductions of 65%, 50% and 33% (heavy, moderate, and light thinnings). Unthinned control plots were also established. Mean stand basal area in the light thinning plots was equivalent to that of the unthinned plots within about 20 y of thinning, and in the moderate thinning plots within about 30 y. At age 55 y, 31 y after thinning, stand basal area in the heavy thinning plots was about 8 m2 ha−1' (about 17%) less than in the unthinned plots. Increment advantages over the controls of 0.59, 0.47 and 0.44 m2 ha−1 y−1 were related to moderate, heavy, and light thinning respectively. Although there were no significant differences (P≤0.05) among treatments, mean diameter for the largest 150 stems ha−1 increased with heavier thinning. Mean net merchantable volume increments and sawlog volumes in all three thinned treatments exceeded those in the unthinned plots, and sawlog volume relative to total volume increased consistently with increased thinning intensity. The moderate thinning plots experienced negligible mortality, produced comparable basal area and more merchantable volume than the unthinned plots, and resulted in increased individual tree sizes and total sawlog volume. This was the only treatment which provided improvement for all these parameters over the ‘do nothing’ (unthinned) option.
Thinning
Basal area
Silviculture
Native forest
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To better understand the long-term basal area and diameter growth response of young, well-stocked, even-aged, mixed-species stands of western hemlock (Tsuga heterophylla (Raf.) Sarg.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) to a range of thinning intensities (heavy, moderate, light, and unthinned), 20 years of posttreatment (i.e., thinning) data were analyzed from 128 permanent study plots at 32 installations in southeast Alaska. Thinning significantly increased the basal area growth of the thinned plots relative to that of the unthinned plots. Basal area growth of the thinned plots decreased with increasing thinning intensity, likely a consequence of the reduction in growing stock with increasing thinning intensity. Diameter growth increased with increasing thinning intensity. Younger stands (typically with smaller pretreatment basal areas and diameters) responded more vigorously to thinning than did older stands, as did stands growing on more productive sites. The models developed in this analysis can be used by land managers to make general predictions of how western hemlock-Sitka spruce stands similar to those investigated in southeast Alaska are likely to respond to different thinning intensities in terms basal area and diameter growth during the first 20 years posttreatment.
Thinning
Basal area
Tsuga
Western Hemlock
Stand development
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