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1.
The use of small-scale harvesting equipment continues to grow in forestry in many regions of the world. This equipment includes various devices and methods used to harvesting that generally are smaller, less expensive and less productive than advanced forestry machines. The objective of this study is to compare the efficiency of five alternative extraction methods implemented in a harvesting unit located in a mixed beech and oak forest ecosystem in northwestern Turkey. A continuous time study was conducted during primary transport operations that included skidding with animal power, skidding with farm tractor, hauling with farm tractor, hauling with forest tractor, and extraction by skyline. Timber was skidded uphill on a skid trail, and an average skidding distance of 100 m for all haulage methods was considered. Average slope of the harvesting unit ranged from 20 to 40 %. Average productivities for respective haulage methods were 3.80, 6.25, 2.80, 5.25 and 10.09 m3/h. Significant differences were found between productivity of haulage methods using one-way analysis of variance. The extraction by skyline, skidding with farm tractor, and hauling with forest tractor were determined to be the most statistically different methods, the productivity of these methods was found significantly higher than the other methods. Skid trails are useful for shortening distances during forest operations and skidding with farm tractor is a productive method in small-scale forestry of Turkey.  相似文献   

2.
Time equations are derived for felling with chainsaw, skidding with cable wheeled skidder, loading with grapple hydraulic loader and trucking of logs within a cut-to-length harvesting method. The continuous time study method was applied to collect data for felling, skidding, loading and a transportation model. Multiple regression analysis via SPSS software was applied to develop the time models. Felling time was found to be highly dependent on diameter at breast height. Skidding distance, winching distance, slope of the trail and piece volume were significant variables for the skidding time prediction model. The loading time model was developed considering piece volume. Transportation distance and load volume were used as independent variables in modeling the transportation time. The net production of felling was estimated at 12 trees/h (56.65 m3/h). The net production rates for skidding, loading and traveling averaged 18.51, 41.90 and 3.32 m3/h respectively. The total cost of harvesting from stand to mill was estimated 19.70 €/m3. The skidding phase was the most expensive component of the cut-to-length method. The bucking and delimbing components were less costly than the other logging phases. The results of this study can be used for harvesting planning and productivity optimization.  相似文献   

3.
The productivity of skidding tractors in intermediate harvesting operations has not been determined in Mpumalanga, South Africa. The objective of this study was to develop a productivity model using a farm tractor in first thinning operations in Pinus patula compartments. A work study design was used to assess the performance of a skidding agricultural tractor. From 350 samples, important data variables collected were elemental times for each work cycle, extraction distance, slope and load volume. Stepwise and subsets regression analyses were conducted prior to multiple linear regression analysis. Analysis of variance was used to compare mean productivity estimates of the different models developed. Results showed that the best model was estimated by an interaction of distance × slope (ds), distance × load volume (dv) and slope × load volume (sv) as follows: ln(?2) = 1.33–0.00154ds + 0.00174dv + 0.161sv. The mean estimate for this model was 5.036 m3 m h?1. The developed models predicted similar results to estimation results of the observed model, although there were statistically significant (P < 0.001) differences among mean estimates (3.6–5.5 m3 m h?1). All of the three models yielded R2adj. = 38%; SE = 0.458% at P < 0.001. It can be speculated that the remaining variation not explained by the models may be associated with long extraction distances, delays and the effect of slope as a main variable in the model. While the developed models mirrored reasonably well with the observed estimates of skidding productivity, these models should not be stretched to conditions dissimilar to those of their generation. Future research focus should be made on (1) effects of weather conditions and vehicular characteristics on skidding productivity and (2) the effect of winching lines on skidding productivity.  相似文献   

4.
The authors tested two mini-yarders, one for uphill and the other for downhill extraction. The two machines were modern commercial models, offering state-of-the-art yarding technology on a miniature scale and at a much lower cost than required for purchasing a full-size tower yarder. The two units must not be regarded as alternative, but rather as complementary, since they offer different capabilities and advantages. Both machines were tested while harvesting firewood from the thinning of young beech stands in Central Italy. The tests indicated that both units can reach a productivity between 1.5 and 2.4 m3 SMH−1, including all delays, as well as set-up and dismantle time. Calculated extraction cost ranged between 24 and over 30€ m−3. The authors calculated a set of regression equations for estimating machine productivity as a function of the main work conditions. The performance of the studied mini-yarders does not seem much inferior to that achieved by professional light tower yarder under the same work conditions, but the lighter construction of the small-scale units may result in a lower resistance to wear and abuse. In any case, mini-yarders seem ideal for deployment under the typical conditions of small-scale forestry, offering a good solution to wood extraction on steep terrain, competitive with animal and winch logging in terms of productivity, cost and operator comfort.  相似文献   

5.
A field-based study was carried out to determine the productivity and production cost of the tree length (TL) and the wood assortment (WA) systems implemented under small-scale forestry conditions in two Scots pine stands in Northern Greece. Tree felling and processing productivity were estimated at 8.64 m3 per productive machine hour (PMH?1) and 10.21 m3 PMH?1, respectively. Wood felling and processing times were strongly dependent on dbh and total tree volume. However, when manual debarking was also considered the productivity rates decreased to 1.96 and 1.43 m3 PMH?1, respectively. Skidding productivity was calculated to be 3.35 m3 PMH?1 for TL and 7.17 m3 PMH?1 for WA, respectively. Strong correlations have been found between the net skidding time and (a) the skidding distance and (b) the load per turn in both wood harvesting systems. Production costs varied greatly, from 19.38 € m?3 up to 44.81 € m?3 of roundwood depending on the harvesting system and the inclusion of debarking. The findings suggest that the WA system is more efficient in terms of productivity and production cost than TL, and that there is a substantial optimization potential. The optimization potential can be encoded in four suggestions: (a) opening up of more forest roads to reduce high skidding times, (b) replacement of manual debarking by mechanical debarking at the sawmill, (c) replacement of old pieces of equipment with newer ones and (d) training of the existing workforce.  相似文献   

6.
Modern forwarders are an effective extraction option for timber harvesting operations that provide the opportunity for higher levels of mechanization. With their ability to carry logs from the forest to the roadside or processing areas, they have an established lower environmental impact in comparison to tree-length skidding options. However, little is published regarding their productivity potential or the factors that influence productivity. Three case studies were carried out; (1) a selective harvest in Calabria, Italy, with a smaller 12 t capacity John Deere 1110E, (2) a clear-cut on the West Coast of New Zealand, with a larger 19 t capacity John Deere 1910E and (3) a larger clear-cut operation in Canterbury, New Zealand, with two John Deere 1910E forwarders. An elemental time and motion study was used resulting in 73.4 h of detailed data, with 159 cycles extracting 2241 m3 of timber. Productivity models were created for all three sites as well as one combined model. Average cycle time was 33.2, 24.2 and 22.8 min, and average productivity 24.6, 37.1 and 42.7 t per productive machine hour, respectively. Cycle time was the fastest, and consequently productivity the highest, at the Canterbury site where the terrain roughness was low, overcoming any effect of the average small piece size (0.59 m3). Travel speed was slowest at the West Coast site showing the effect of wet and difficult terrain, with travel empty speed being just 3.8 km/h, compared to 6.7 and 6.9 km/h at the other two sites. Productivity at the two clear-cut operations was significantly higher than the selective cut, compounded by the use of the larger capacity forwarders. Distance and payload were significant factors for each cycle time model; in the combined model the sites were also significant. The calculated unit cost of forwarder extraction in the sites ranged from €2.55 to €4.70/m3. For regions such as southern Italy that have relatively low levels of forest mechanization, this information can be used to help design and improve more traditional labor-intensive harvesting systems.  相似文献   

7.
The small-scale harvesting equipment system has been and continues to grow in use in forestry operations in some regions in the world. This harvest system can include a range of equipment types, such as feller-bunchers or chainsaws, skidders or farm tractors, and chippers. These machines are generally smaller, lower cost and less productive than larger, more advanced forestry machines. The objective of this project was to investigate the feasibility of a small scale harvesting system that would produce feedstock for a biomass power plant. The system had to be cost competitive. A boom-type feller-buncher, a small grapple skidder and a chipper were tested as a small-scale system. In this study, feller-buncher and skidder productivity was determined to be 10.5 m3 per productive machine hour, and production for the chipper was determined to be 18 m3 per productive machine hour. Production from the system did not reach the desired levels of 4 loads/day (25 m3/load); however, the system was able to produce about 3 loads/day. The results showed that the system currently could fill a roadside van for $16.90/m3, but suggested machine modifications could potentially reduce the system cost to $12.73/m3. Residual stand damage was minimal, especially on flatter ground and not operating on a slash layer. Soil disturbance from the harvesting system was predominantly undisturbed or classified as a shallow disturbance.  相似文献   

8.
Most timber harvesting operations in the southern Mediterranean area of Italy can be considered to be in an early stage of mechanization. It is mainly based on agricultural tractors that are sometimes equipped with specific forest-related accessories such as winches, hydraulic cranes, or log grapples. In recent years, there has been an increase of specialized forestry machines working in Calabria, southern Italy, including forwarders, skidders and cable yarders. This study assesses the efficiency and costs of extraction using forwarders, as a mechanized alternative to agricultural tractors and horse logging. Time studies were conducted to quantify the productivity and operational cost of log forwarding for two John Deere forwarders in two different coniferous stands: (A) Calabrian pine and (B) silver fir. The empirical time study included 100 forwarding cycles (i.e., 50 for each site) that were broken down into four different work phase elements. Models for cycle time, total productivity and individual work phases were calculated. The average load per cycle was 11.8 m3 in stand A and 9.97 m3 in stand B and the average one-way forwarding distance was 306 m in A and 597 m in B. The average productivity per scheduled machine hour (SMH) was 14.4 m3 in A and 15.7 m3 in B, while the costs, calculated to be 3.60 €/m3 in A and 4.90 €/m3 in B, were considered lower respect traditional methods.  相似文献   

9.
Both model and field estimations were made of the damage inflicted to coffee plants due to the harvest of timber shade trees (Cordia alliodora) in coffee plantations. Economic analyses were made for different coffee planting densities, yields, and both coffee and timber prices.Damage due to tree felling and log skidding should not be a major limitation to the use of timber shade trees in coffee plantations. The timber price that would balance all discounted losses and benefits to zero, for scenarios with and without trees ranged between 8–20 US $/m3 (current overbark log volume at the saw mill yard is US$ 66/m3). There will be lower margins for coffee damage in high yielding plantations, specially in years of good coffee prices. Nevertheless, the use of timber shade trees is recommended even in these scenarios.  相似文献   

10.
A field-based study was carried out to broaden our knowledge of fully mechanized cut-to-length harvesting productivity in naturally grown forests in the northern European part of Russia (NEPR). The recorded data comprised 38 midsized single-grip harvesters (JD 1270D) in clear-cutting operations in the Karelia, Komi, Vologda, Leningrad, Tver, and Kirov regions in NEPR, 4.3 million felled trees, and 1.4 million m3 u.b. (under bark) of processed timber. Harvesting operations were conducted in forest stands composed of spruce (48% on average), pine (19%), birch (22%), and aspen (11%), with an average stem volume 0.31 m3 u.b. The cut-to-length harvesters produced from 4.3 to 14.9 m3 u.b./productive machine hour (PMH) and 16.0–49.5 m3 u.b./stem processing machine hour (S proc MH). A machine evaluation analysis and a regression analysis were used to formulate models for predicting cutting productivity of modern single-grip harvester. The regression models were developed to estimate the productivity of the harvesters in the regions taking into account two significant factors influencing the productivity: the stem volume and tree species of the felled trees. Productivity/cubic meter u.b. of processed timber/PMH was calculated according to stem volume and tree species distributions in most forest-covered NEPR regions. Further research is suggested to improve the developed productivity models and to allow prediction of system performance over a broad range of stand and site conditions.  相似文献   

11.
A critical mass of farm forestry and private forestry is now developing in Ireland with over 211,000 ha planted since 1980, with 190,000 ha of this planted since 1990. Currently, 90,000 ha of private forests are over 10 years of age, with 41,000 ha over 15 years of age. This paper examines the potential of the farm forest resource in Ireland and highlights some issues that need to be addressed in order that the full potential of farm forestry is realised. It is estimated that 876,000 m3 of timber is currently available from forests through removals from thinning operations from plantations that are at or have passed first thinning age. Cumulative volume output from thinning could be as high as 1.9 M m3 by 2010 increasing to 5.9 M m3 by 2015. Farm forestry has the potential to be a financially important farm enterprise with 15% of farmers (16,460) currently engaged in forestry in Ireland. The development of volume production forecasts will provide crucial supply information for gearing up of the wood-processing sector for additional volume from farms. However many enterprises face high harvesting and extraction costs. Solutions to overcoming economies of scale due to the small size of plantations (averaging 9.2 ha) are proposed using methods to group forestry operations together. The network of small sawmills throughout the country is favourable for private growers as analysis indicates that 82% of private forests are within 32 km of a sawmill and efforts to stimulate local processing are being encouraged. Financial analysis indicates that farmers can increase forestry returns by thinning their plantations. The risk of windthrow to plantations is one of the major factors that can lead to financial losses in farm forestry in Ireland and can be reduced by adequate management planning. A series of forestry extension programs will provide farmers with adequate information to help aid decision-making in managing their plantations.
Niall FarrellyEmail:
  相似文献   

12.
Waste wood was studied in an economic enterprise by logging, function, tree species and log size in four Caspian hardwood sites. Damaged logs were recorded with additional information obtained for the location, dimensions and type of damage. The data were analyzed statistically to determine significant differences of damage during logging process. The results indicated that animal harvesting systems cause more volume (40.5% of log volume) and value loss (89.5 $·m?3) to logs than mechanized harvesting systems (13.9% and 6.0 $·m?3), also bucking resulted in significantly more volume (9.9% of log volume) and value loss (5.5 $·m?3) when compared to skidding (0.2% of log volume and 0.2 $·m?3), decking (0.4% of log volume and 0.2 $·m?3) and loading (0.2% of log’s volume and 0.3 $·m?3) operations. Study showed that the processes of skidding, decking and loading of logs have very little impact on damage levels. Volume and value losses of damaged logs are not sensitive to tree species and log size. The information from the field study is important in creating new guidelines or training to help minimize hardwood log damage during the timber harvesting process.  相似文献   

13.
通过对FYJ-1型轮式抚育伐集材拖拉机与畜力集材两种生产作业方式进行比较,对两个冬运期集材作业的实测数据进行整理与核算表明,集材拖拉机比畜力集材生产方式的经济效益提高2.99倍,生产效率提高2～3倍。 FYT-1型轮式抚育伐集材拖拉机不仅适合在零星分散的森林抚育间伐场地作业,更适合在集中连片和远距离（800m以上）、坡度适中的场地作业。  相似文献   

14.
将轮式小拖拉机进行改造,装配绞盘机和搭载板后进行集材,在集材距离200~300 m时,日集材量为:冬季20~30 m3,夏季15~20 m3,比畜力集材提高了4~6倍;集材成本为15~20元.m-3,是畜力集材的50%。利用轮式小拖拉机进行集材,对地表及幼苗幼树的破坏程度大幅度降低,是目前可供选择的一种较好的集材方式。  相似文献   

15.
Portable sawmilling trials with Acacia aneura (mulga) and A. cambagei (gidgee) have been undertaken to estimate the private landholder costs associated with small-scale timber production from woodlands in western Queensland, Australia. A time study of harvesting and milling operations facilitated estimation of landholder labour input requirements. The scarcity and small size of millable logs, coupled with the prevalence of timber defects, make harvesting and portable sawmilling of western Queensland acacias an expensive undertaking for landholders. The cost of producing sawn timber that meets the High Feature (HF) grade of Australian Standard AS2796 is estimated at between A$3,000/m3 and A$3,400/m3 of HF timber.  相似文献   

16.
Mechanised thinning operations can be carried out in the forest where skid roads are provided on which harvesters and forwarders can move. In the transition to continuous cover forestry (CCF) it is better to keep a thinner network of skid roads in the forest. Instead of tracks for harvesters and forwarders, these areas can be used for younger generations of trees. Moreover, fewer skid roads in the forest environment make the stand more natural. Fewer skid roads were introduced in this research as an alternative thinning operation with midfield1 (MF) to the most popular mechanised thinning operation with skid roads2 (SR). The aim of this paper is to analyse the productivity and economic aspects of thinning operations based on harvesters and forwarders, where there are different distances between skid roads. In both of the operations, harvesters and forwarders were used, but in the MF operation a chainsaw was additionally used to cut trees beyond the reach of the harvester boom. The distances between skid roads in the MF operation were 35–38 m, while in the other they were 18–20 m. The research was carried out in premature pine stands in a flat terrain in Poland. Bigger productivity and lower costs were found in the MF thinning operations. In the younger 44-year-old stand, the average harvester (Timberjack 770) productivity (in operational time) in the MF operation was 5.87 m3h−1 and in the SR operation 4.52 m3h−1; forwarding provided by the Vimek 606 6WD achieved a productivity of 5.03 and 4.52 m3h−1, respectively. In the older 72-year-old stand, the Timberjack 1270B productivity was 11.53 m3h−1 in MF and 8.70 m3h−1 in SR; the Timberjack 1010B forwarder achieved 11.22 m3h−1 (MF) and 8.84 m3h−1(SR).The costs of harvesting and forwarding 1 m3 of wood were lower in the MF operations. In the younger stand, harvesting costs were 5.78 €/m3 (MF) and 6.72 €/m3 (SR) while forwarding costs were 1.94 and 2.18 €/m3 respectively. In the older stand, harvesting costs were 5.58 €/m3 (MF) and 6.78 €/m3 (SR); the forwarding costs were 2.65 €/m3 (MF) and 3.41 €/m3 (SR).  相似文献   

17.
我国工程索道技术装备及其发展趋势   总被引：7，自引：0，他引：7  
阐述我国工程索道技术装备研究进展,包括绞盘机、跑车及索道附属装置的开发研究;重点分析绞盘机5大技术参数和跑车4大工作机构以及在各种工程索道中的应用效果;指出工程索道技术装备在木材集运、水利水电、公路桥梁和土建施工等吊装工程中的发展趋势及应用前景.  相似文献   

18.
As forests of the eastern United States become fragmented into smaller ownership parcels, there is a growing need for timber harvesting contactors who can economically harvest timber and perform silvicultural operations on small tracts. Traditional large-scale harvesting operators are ill-suited for work on small parcels, due to their high fixed costs. By contrast, small-scale operators, characterized by few workers and low capital investment, offer an opportunity to serve this landowner segment. This paper presents financial and productivity results from a small-scale timber harvesting pilot study conducted on small forested parcels in western Maryland, USA. Acceptable financial performance is possible for these operations, provided that the operator pays close attention to the important factors determining productivity and profitability, including: (1) average tree volume, (2) net delivered price, (3) time utilization, and (4) distance to the site. Although profitable harvesting of saw log quality trees on parcels less than 10 ha is possible, harvesting of small or poor-quality trees remains economically unattractive.  相似文献   

19.
ZEHETMAYR  J. W. L. 《Forestry》1965,38(1):113-120
The effect of varying length of pulpwood is discussed in relationto place of conversion, loading, length of lorry, stacking spaceat roadside, method of skidding, and the preparation of loadsafter crosscutting at stump. The conclusion is reached that for Scottish upland conditionspulpwood should be prepared in 10- to 12-feet lengths in twostages, the feller preparing loads for skidding and the horseor tractor roughly piling the unbarked pulpwood at roadsidefor mechanical loading on to long-distance transport. For theFort William mill a standard length of 10 feet, with tolerancedown to 8 feet, will be adopted. Mechanization is not envisaged for some years beyond chain saw,tractor-mounted double-drum winch, and lorry- or tractor-mountedcrane with hydraulic grab, while the horse will play its partin skidding for at least the next five years. Logging teamsof four to eight men will be required and are being trained.  相似文献   

20.
《Southern Forests》2013,75(4):195-200
At least 200 000 m3 of timber is harvested annually using semi-mechanised harvesting systems on the Viphya forest plantations in Malawi. Although these systems have long been used on the Viphya, no investigation on their productivity has so far been reported. Additionally, the absence of localised productivity analyses in Malawi has created a paucity of information on appropriate timber harvesting systems for production maximisation and cost minimisation. The objective of this study was to compare the production rates and operational costs of chainsaw/grapple skidder (semi-mechanised) and feller-buncher/grapple skidder (mechanised) harvesting systems in order to determine the economic feasibility of mechanised systems in the Viphya forest plantations. The study was conducted in Pinus kesiya compartments at the Kalungulu and Champhoyo forest stations of the Viphya forest plantations. A work study approach was followed to capture harvesting time and volume data for the semi-mechanised system. Secondary work study data were used to simulate productivity of the mechanised system on similar compartment conditions. A timber-harvesting costing model was used to analyse the results. The study showed that the simulated mechanised system was associated with lower operating costs and inventories with higher production rates than the semi-mechanised system. The cost marginal difference was US$0.89 m–3. It was therefore established that migration to mechanised systems could optimise timber harvesting productivity on the Viphya in future, if optimal volumes are available to ensure the efficient application of the mechanised harvesting system.  相似文献   

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