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1.
Meghdad Jourgholami 《林业研究》2012,23(2):333-337
Hyrcanian (Caspian) Forest in northern Iran has a richness of biological diversity, with endemic and endangered species. The usage of ground-based skidding is well accepted practice for the extraction of timber from the forest, but this operation has tended to cause the greatest environmental problems. The aims of the study were to evaluate and comparison of operational impacts, residual stand damage, regeneration, and to quantify these effects such as: the extent of the damage, wounding patterns, size and distribution after logging operations that utilized two different methods: short-log and long-log. A Timberjack cable skidder was used and the study location was in the Kheyrud Forest. Post harvesting assessment of damage to the residual stand was compared along skid trail by 100% inventory method and also for the assessment of regeneration damage along winching strips. The results show that along winching strips the percentage of damage to the regeneration was 44% and 36%, while the tree damages along skid trails reached 2.3% and 4.1% in the short-log and long-log methods, respectively. The greatest average amount of damage to a bole occurred along the first 1 m up from the ground (97%) and also within 4 m of the skidder centerline (80%). These results show that the short-log method causes less damage to the residual stand than the long-log method. Tree location to skidder trail appears to have a significant effect on the number and height of scars on a tree. Well designed and constructed trails should be wide enough to allow wood extraction from the forest. Damage to the residual stand might be reduced by proper planning and training of logging crews. 相似文献
2.
We investigated the effects of skidder traffic intensity, soil disturbance intensity, and canopy removal intensity on the richness, diversity, composition, and cover of the entire ground flora (woody and herbaceous vegetation ≤2 m tall), various individual life forms, invasive/noxious species, and species with different requirements with respect to moisture, nutrients, heat, and light (synecological coordinates) in a mesic northern hardwood stand 6 years after a clearcut-with-reserves regeneration harvest removed 50–100% of the canopy. Skidder traffic was restricted to a network of trails and a global positioning system (GPS) tracked skidder movement to quantify the number of passes at pre-established sampling points along the anticipated soil disturbance gradient on and off skid trails. Soil disturbance intensity within the top 15 cm of soil was quantified by relativized resistance to penetration (RRP) compared to untrafficked plots; post-harvest increases in RRP ranged from 81 to 272%. Regression analysis and ordination revealed a pattern of increasing difference from pre-disturbance composition with increasing skidder traffic (i.e., forest floor disturbance), with increased RRP (i.e., soil compaction) and (less so) canopy removal intensity. The ground flora shifted from interior forest species such as Anemone quiquefolia, Aralia nudicaulis, Clintonia borealis, Maianthemum canadense, and Oryzopsis asperifolia to more ruderal, invasive/noxious, and disturbed-forest species such as Aster lateriflorus, Cirsium spp., Phleum pretense, Rubus idaeus, and Trifolium spp. The relative resistance of the initial ground flora to change (inverse of the distances between pre- and post-harvest samples in ordination space) was nonlinearly related to skidder traffic intensity and linearly related to RRP, indicating that the largest compositional changes occurred with the first few passes of the skidder. Mean plot scores for the synecological coordinates revealed that the post-harvest species were on average less demanding of water and nutrients; the opposite was true for light. Plots exposed to less skidder traffic and RRP had higher herb cover and higher nutrient scores; those with more skidder traffic and higher RRP levels had higher shrub cover and higher light scores. We conclude that protection of the ground flora from forest floor and soil disturbance requires careful planning of skid trail networks. Concentrating skidder traffic to a designated skid trail system can result in less area disturbed and spatially connected networks of larger, untrafficked remnant forest patches that may maintain species that are sensitive to forest floor and soil disturbance. 相似文献
3.
拖拉机对集材道土壤及苗木生长影响的研究 总被引：7，自引：1，他引：6
集材道土壤受拖拉机反复走行作用产生地表轧乱和土壤压实现象，造成水土流失和腐殖质丧失，这对更新苗木的生长产生了不良影响．本文通过实地调查测定，应用灰色系统理论，研究了拖拉机集材时集材道上土壤硬度、孔隙度的变化及对苗木生长的影响。在履带式拖拉机集材道上，土壤的硬度、孔隙度都比轮式拖拉机集材道上的大。与土壤硬度相比，孔隙度对苗木生长的影响更大些。从而得出了就苗木高生长而言，履带式拖拉机比轮式拖拉机的损害要小。 相似文献
4.
Donna Perison Joseph Phelps Christina Pavel Robert Kellison 《Forest Ecology and Management》1997,90(2-3):171-185
This study was initiated on the South Fork Edisto River in South Carolina to investigate and compare the impacts of two different harvest methods (helicopter and rubber-tired skidder) on the ecological structure and function of a blackwater forested wetland. The two harvest treatments were chosen to represent a broad spectrum of potential impacts and were compared to an undisturbed site. Following harvest in 1991, functional responses in vegetative productivity, herpetofaunal populations, and soil and water quality were evaluated in 1992 and 1993. Herbaceous biomass was greater on the helicopter and skidder treatments than on the undisturbed control. In general, the biomass measured on the skidder treatment was not significantly different from the biomass measured on the helicopter treatment. Higher decomposition rates were noted in the harvested areas as compared to the control. This was mainly attributed to higher soil temperatures, which accelerated microbial activity. Increased decomposition rates may have been responsible for elevated levels of ammonium and organic carbon observed in ground water samples. A total of 29 species of herpetofauna (10 amphibians and 19 reptiles) were observed during the study. Salamanders were found more often in the undisturbed control. Reptiles were observed more frequently in the harvested area. Although herpetofaunal species composition was different between harvest and control, indices of diversity were similar. 相似文献
5.
The importance of environmental and economical aspects in sustainable forest management (SFM), demands a continuing need for the application of efficient methods in this field. In this paper, we applied analytic network process (ANP) with benefits, opportunities, costs, and risks (BOCR) to evaluate four existing wood extraction methods (rubber-tired skidder, tracked skidder, cable logging and animal skidding) and select the best one based on SFM strategies in the Caspian (Hyrcanian) Forest, in northern Iran. The required data were obtained either from the previous studies or through pairwise comparisons conducted by a panel of forest engineering experts. Based on the BOCR subnetworks and their corresponding criteria, four alternatives were synthesized. ANP analysis indicated that the benefits and risks were more important in terms of decision-making, compared to the opportunities and costs. Finally, the alternative of ‘rubber-tired skidder’ was selected as the most suitable method for meeting SFM strategies. The decision framework proposed in this study offers a means for the reorganizing and planning of timber harvesting operations as an integral step toward SFM. By making minor adjustments for local conditions, this decision framework can be adapted for many other regions and countries. 相似文献
6.
多功能轮式集材拖拉机搭载板装置的设计研究 总被引：1，自引：0，他引：1
通过对我国集材拖拉机发展沿革及目前林业生产作业条件分析,研发一种新型多功能集材拖拉机对目前林业生产具有重要意义.集材装置是集材拖拉机最具有特点的主要工作装置,本文对多功能轮式集材拖拉机集材装置（搭载板装置）整体结构进行设计.首先根据集材拖拉机趟载量要求确定搭载板整体结构尺寸,宽度为1 050 mm,长度为1 219 mm,厚度为20 mm.其次对搭载板辅助结构进行设计计算,使用Solid Works三维绘图软件建立搭载板的3D模型.最后基于有限元校核搭载板的强度,得到搭载板在最大压力载荷下的位移云图和应力云图,结果表明所设计的搭载板满足强度要求. 相似文献
7.
森工企业在拟定采集工艺时,必然要考虑生产效率、经济效益和生态问题.在新的作业条件下,需要开发新型集材装备,既能满足木材生产又能减少对林地环境的不利影响.三角履带是融合了轮胎与履带行走机构的优点而研发的新型行走机构,能适应各种恶劣的环境.本文对多功能集材机三角履带的主参数做分类概述,三角履带的主参数主要由集材机的相关参数和环境的相关数据共同决定.运用建模的方法对5种不同集材机主参数进行计算,通过实验获得诸如坡度、伐根高度等林区作业环境数据,运用统计方法进行数据处理,然后依据以上数据通过理论推导出5种不同多功能集材机三角履带的参考值. 相似文献
8.
Rostam Mousavi 《林业研究》2012,23(4):691-697
The performance of the skidder Timber jack 450 C was presented in timber skidding of non-coniferous trees in hilly and mountainous conditions.An empirical time study was conducted to evaluate the current skidding system in Hyrcanian forest in northern Iran for improving production rate of skidding and finding out the production cost for planning.Based on the identified elements of skidding work phase and 130 recorded cycles,we calculated the models for effective time consumption,total productivity,and unit cost.The validity of the model was tested at 95% confidence interval.The average load volume per cycle was 2.82 m 3,average one way skidding distance was 450 m,and the average slope was 18%.The average travel speed of unloaded skidder was 5.8 km·h-1,and the average speed of loaded skidder was 0.1 km·h-1 higher than the speed of the unloaded ones.The travel speed was predominantly affected by longitudinal slopes and types of strip roads.The average speed of pulling the cable was 1.16 km·h-1,and that of load winching was 0.74 km·h-1.The average outputs in skidding was 10.6 m 3 ·h-1 and the unit cost was 12.1 US$ per hour.The time consumption and productivity of skidding depends on distances and slope,number of logs per cycle,volume,log length,etc.However,the influence of variables is not the same. 相似文献
9.
10.
Hans R. Heinimann 《Journal of Forest Research》1998,3(1):1-9
Road spacing on slpes depends on the underlying off-road transportation technology. One major decision in road network planning
is to determine under what terrain conditions ground- or cable based extraction systems should be applied. The present investigation
aims to develop a road spacing model for steep slope conditions and to implement a total cost model for skidder and cableyarder
based road network concepts. The study analyzes transportation and road geometry to specify the relationship between road
density, slope gradient, and road spacing. Production functions for skidder and yarder-systems make it possible to derive
transportation cost as a function of road density and slope gradient. A total cost function integrates road building cost,
harvesting strategy, and production economics to derive optimal road density for the two network concepts. The difference
between the cost levels at optimum road density is an indicator for differentiating cable and skidder-based extraction systems.
The model was implemented as a Visual Basic add-in for Microsoft Excel spreadsheet software. This flexible approach makes
future adaptations and changes very easy due to the modular concept. The validity of the model is limited to the production
functions of the underlying off-road transportation technologies. Future work needs to develop production functions for the
state-of-the-art technologies and to improve the road building cost model. 相似文献
11.
《Forest Ecology and Management》1998,112(3):281-287
Soil environmental conditions were investigated in nine stillwater swamps dominated by pondcypress (Taxodium distichum var. nutans) in north central Florida. Three swamps were left unharvested (control); three were harvested, but surrounding slash pine plantations were left intact (swamp harvest); and three were harvested along with the surrounding slash pine plantations (swamp+upland harvest). Measurements of soil redox potential (Eh) and other soil and water properties were collected for 5 months before harvesting (December 1993–April 1994) and for 2 years after harvesting (May 1994–May 1996). No significant differences in water level resulted from harvesting, although control swamps became dry and harvested swamps remained flooded shortly after harvesting. Eh in the swamp+upland harvest treatment was lower than in the control treatment for only 1 month (July 1994) after logging but was also lower in areas where the soil was compacted by skidder equipment. Short-term increase in water level and soil compaction by skidder trafficking appear to have minimal long-term effects on soil environmental conditions. 相似文献
12.
通过对沾河林业局现有的兴安落叶松人工林抚育机械即割灌机、油锯、集材机械进行分析和研究,结果表明：国产机型与国外先进机型相比,还存在着很大的改进空间。短距离集材,畜力集材具有优势;随集材距离加大,拖拉机集材效率明显高于畜力集材。影响集材效率的关键因素是回空和重载时间。 相似文献
13.
A study was conducted to investigate the effects of skid trail slope and traffic levels on soil disturbances at two soil depths
(0–10 and 10–20 cm). The treatments were set at four traffic levels (2, 7, 12 and 20), two slope classes (<20% and >20%) and
two soil depths (0–10 and 10–20 cm). Results show that skidder traffic, longitudinal slope and soil depth have significant
effect on soil bulk density in skid trail. Comparison of average soil bulk density in different traffic levels shows that
there are significant differences in average bulk density between different traffic levels and control (p<0.05). The average bulk densities in different slopes and soil depths are significantly increased with increase in traffic
levels, maximized at 12 passes (p<0.05), but there are no significant differences between 12 and 20 passes. The interaction effects between traffic and soil
depth are significant (F
0.05,3=0.109, p<0.001). For all traffic treatments, there are significant differences in soil moisture content between the two slope classes
and the two depths (p<0.001). However, the interaction effects between traffic levels and slope classes are not significant (p >0.05), although skidder traffic and slope affected soil moisture content. 相似文献
14.
The impact of skidding operations on forest soils can be divided into three major categories: soil profile disturbance, soil compaction, and soil puddling and rutting. The present study was designed as a factorial experiment in the Kheyrud Forest with a Timberjack cable skidder to evaluate the influences of number of machine passes and soil moisture of skid trails on rutting over a fine-grained soil, and to quantify these effects. The effects of soil moisture of 20% 30%, 30% 40% and 40% 50% and different levels of compaction were studied. Compaction treatments were applied using different numbers of skidding passes (1, 5, 10, 15, 20, 25, 30 times). Result shows that an increase in the number of machine passes could increase rut depth, but the majority of rutting was occurred after the initial few machine passes. Also rut depth at soil moisture of 40% 50% was higher than rut depths at soil moisture of 30% 40% and 20% 30%. The average rut depth in soil with 20% 30%, 30% 40% and 40% 50% moisture was 17, 22 and 35 cm, respectively. Rut depths were increased significantly with soil moisture and number of machine passes. It is suggested that skidding operations should be planned when soil conditions are dry in order to minimize rutting., but if skidding must be done under wet conditions, the operations should be stopped when machine traffic could create deep ruts. 相似文献
15.
《Southern Forests》2013,75(4):329-338
Supply chain management principles were analysed by investigating the effects of smaller-scale and incremental interventions in a forest-to-mill value chain on financial returns and forest resource use in an Eastern Cape case study area. Three previous studies provided input by determining fibre balances, a terrain factor, and primary and secondary transport travel speeds and efficiencies. Network analysis, combined with raster-based GIS, analysed different primary and secondary transport scenarios. The forest road network was repeatedly refined through theoretical removal of lower-class roads and subsequent upgrades of remaining roads, and the timber resource flowed over the remaining road network to the mill. Four road networks, including the existing and unrefined network, were studied. With sequentially improved secondary transport travel speeds, primary transport efficiency and fibre use, the net financial returns of the various scenarios were determined by applying discounted cash flow analysis (NPV). To address all possible combinations, 144 unique scenarios were created. The highest NPV achieved was R300.8 million associated with a highly upgraded road network and associated fast secondary transport speeds, cable skidder extraction, motor-manual felling and cross-cutting at the merchandising yard, all factors at optimal performance. The lowest NPV was R40.4 million associated with a simplified road network, low secondary transport speeds, cable skidder extraction, mechanised felling, and roadside merchandising and at status quo systems performance. Examination of individual factors found systems performance, secondary transport speeds and road network had the greatest influence, with systems performance and fibre losses providing the largest impact. Secondary transport speed followed as nine of the top 10 NPV scenarios were achieved with the highest possible road design speeds. Higher-class networks consistently outperformed the baseline and simplified scenarios. Harvesting system had limited effect. When operating at peak performance, using a merchandising yard becomes a better choice. There was no clear difference in terms of felling method or skidder type. It is clear that the optimised use of potentially the most productive machine, for example in one system, does not provide the best final results and that it is the basic harmonisation of all factors that must be taken into account. As in all three previous and related studies, the human element played a role. 相似文献
16.
《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
17.
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
18.
明式椅类家具是中国古典家具中的经典范例.其中椅类靠背设计对椅类家具又起到了画龙点睛的作用.本文以明式椅类家具靠背选材和设计为研究内容.通过大量分析得出,明式椅类靠背用材分为主要用材和辅助用材.其选材、用材要求质地均匀,讲究纹理.在设计方面,注重构思巧妙、造型简洁,装饰手法多样,题材丰富,寓意吉祥.研究明式椅类靠背选材和设计,旨在揭示明式椅类靠背选材和设计的表现规律,为现代椅类家具靠背设计提供思想启示和理论支持. 相似文献
19.
本文阐述了东方红60推土机座椅的振动测试方法和分析手段.得出了测试和分析结果.通过测取座椅和座椅悬挂点的自动率谱和传递函数.分析了该机座椅的动态特性.本文还简单介绍了车辆乘坐舒适性评价指标和标准 并采用ISO2631推荐的常用评价方法(疲劳—减效界限)对座椅进行了乘坐舒适性评价.结果表明.东方红60推土机的座椅舒适性尚需进一步改善. 相似文献
20.
Hlne Gondard Franois Romane James Aronson Zuheir Shater 《Forest Ecology and Management》2003,180(1-3):165-174
The objective of this study was to analyze soil surface disturbances resulting from logging tractors, of different types (skidder and forwarder), used for clear-cutting in natural Aleppo pine forests and their consequences on plant species and functional group diversity.
Results indicate that shallow disturbances (litter left in place or removed) were more frequent than deep disturbances (topsoil removed, subsoil exposed, rut exposed) regardless of the logging tractor used. The forests with previously cultivated terraces were the least disturbed. Moreover, with the aid of a functional group analysis we distinguished four plant species response groups to soil surface disturbance types. The mosaic created by these groups after clear-cutting and log removal probably contributes to a rapid auto-regeneration of a mixed plant community similar to that existing just prior to the clear-cutting. 相似文献