Croatian Journal of Forest Engineering最新文献

{"title":"Infrastructure Requirements for Clear-Fell Harvesting of Small-Scale Plantation Forests in New Zealand","authors":"Jacob Allum, Campbell Harvey, Rien Visser, Stephan Hoffmann","doi":"10.5552/crojfe.2024.2185","DOIUrl":"https://doi.org/10.5552/crojfe.2024.2185","url":null,"abstract":"Background: Small-scale forests (woodlots) increasingly account for a greater proportion of the total annual harvest in New Zealand. There is limited information on the extent of infrastructure required to harvest a woodlot; road density (trafficable with log trucks), landing size, or the average harvest area that each landing typically services.Methods: This study quantified woodlot infrastructure averages and evaluated influencing factors. Using publicly available aerial imagery, roads and landings were mapped for a sample of 96 woodlots distributed across the country. Factors such as total harvest area, average terrain slope, length/width ratio, boundary complexity and extraction method were recorded and investigated for correlations.Results: The average road density was 25 m/ha, landing size was 3000 m2 and each landing was serviced on average 12.8 ha. Notably, 15 of the 96 woodlots had no internal infrastructure, with the harvest completed using roads and landings located outside of the woodlot boundary. Factors influencing road density were woodlot length/width ratio, average terrain slope and boundary complexity. Landing size was influenced by average terrain slope, woodlot length/width ratio, and woodlot area.Conclusion: The results provide a contemporary benchmark of the current infrastructure requirements when harvesting a small-scale forests in New Zealand. These may be used at a high level to infer the total annual infrastructure investment in New Zealand's woodlot estate and also project infrastructure requirements over the foreseeable future.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" February","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using Cyclic CBR Method to Determine Resilient Modulus of Hydraulic Binder Stabilised Road Pavement Base Layers","authors":"Péter Primusz, Balázs Kisfaludi, József Péterfalvi","doi":"10.5552/crojfe.2024.2214","DOIUrl":"https://doi.org/10.5552/crojfe.2024.2214","url":null,"abstract":"The mechanistic-empirical (E-M) design of pavement structures requires knowledge of the elastic modulus of the layers comprising the structure. The necessary cyclic (dynamic) triaxial testing is expensive and cumbersome for low-volume forest and agricultural roads. Opiyo (1995) developed a method called cyclic CBR (cCBR) to determine the resilient modulus (Mr) of granular road construction materials using CBR testing equipment. The present study tested the cCBR method on silty, fine sand stabilised with lime and a lime-cement mixture. For the test, 24 test specimens were prepared by adding 3, 5 and 7% pure lime and a 70–30 lime-cement mixture at the targeted 8–23% water content. Three metrics were used to express the bearing capacity of the specimens: (1) the commonly used CBR% value, (2) the Mr value calculated as a function of load force and elastic deformation determined as a result of the cCBR test, and (3) the resilient modulus calculated from the CBR value. The experimental results showed that the initial water content had a greater effect on the bearing capacity than the binder dosage. The present study found the cCBR procedure to be feasible. The test results were converted to a resilient modulus value using the formula developed by Opiyo and Molenaar, respectively. The calculated resilient modulus values from the CBR value exhibited a wide variation. Uzan's formula provided similar results to those calculated by Molenaar's formula. A 250 m long experimental road section was also constructed to verify the laboratory data. Based on the laboratory tests, five different 50 m long stabilisation layers were built. The bearing capacity data measured with the handheld BC-1 LFWD and KUAB-FWD equipment verified Molenaar's formula.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" November","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Prior Tree Marking on Cutting Productivity and Harvesting Quality","authors":"Johannes Pohjala, Mika Vahtila, Heikki Ovaskainen, Ville Kankare, Juha Hyyppä, Kalle Kärhä","doi":"10.5552/crojfe.2024.2213","DOIUrl":"https://doi.org/10.5552/crojfe.2024.2213","url":null,"abstract":"Prior tree marking is used to guide loggers or forest machine operators on which trees to cut to achieve the desirable silvicultural quality of a thinning treatment. In the future, this beneficial but expensive human work could be automated with advanced driver assistance systems. This study aimed to investigate the effect of conventional prior tree marking on cutting productivity and harvesting quality of the first and later thinnings. A comparative time study was conducted with four experienced harvester operators. The operators thinned 4825 stems with the cut-to-length (CTL) harvesting method in eight thinning stands. The time consumption of the different time elements of cutting work was measured to model the cutting productivity with average values or regress these values against the stem volume or density of removal. Prior tree marking increased the cutting productivity by an average of 2.8% in the first thinnings and 2.7% in later thinnings by reducing the time consumption of boom-out (positioning the harvester head for cut) and moving. The operator effect was notable, even though only experienced operators participated in the study. For some operators, prior tree marking did not make cutting work more efficient, and sometimes hampered it. Prior tree marking improved the quality of the remaining stands in thinnings by producing a more accurate density of remaining trees after the harvesting operation in relation to thinning guidelines. When the stands were not marked, the operators chose trees of poor quality with almost the same accuracy as the forester. These findings lay the foundation for the next-generation operators' guidance and decision support systems, which could detect trees around the harvester and guide the operator in tree selection and managing better thinning intensity in cutting work. Although prior tree marking increased productivity only marginally, the improvement in the quality of harvesting operations must be acknowledged.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" May","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Economic Evaluation and Performance of a Tree Planting Machine Performing in Two Different Slope Classes and Conditions of Harvesting Slash","authors":"Rafael Ribeiro Soler, Saulo Phillipe Sebastião Guerra, Guilherme Oguri, Sérgio Augusto Rodrigues","doi":"10.5552/crojfe.2024.2209","DOIUrl":"https://doi.org/10.5552/crojfe.2024.2209","url":null,"abstract":"In recent years, fully mechanized planters have gained attention in Brazil on flat to steep terrain. A field study was conducted to analyze the potential of a planting machine composed of a hydraulic crawler excavator and a planter unit to perform soil preparation and planting in two slope classes and two conditions of slash presence. The experimental area was divided according to slope – undulating (8% to 20%) and strong undulating (20% to 45%) – and the presence of slash. Slope class did not significantly affect productivity, nor was there a significant interaction effect between the slope and slash factors. The presence of slash proved to be statistically different, with mean productivity of 236 seedlings hour-1 when reloading the carousel in an area without harvesting slash. Tree planting machine utilization was 75.13%, and the mechanical availability was 79.6%. The presence of slash significantly reduced the tree planting machine productivity, including the seedling reloading time, suggesting a newer research line for fasters reloading seedling systems.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" January","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shortage of Labour Force in Forestry of Bosnia and Herzegovina – Forestry Experts' Opinions on Recruiting and Retaining Forestry Workers","authors":"Mario Šporčić, Matija Landekić, Marijan Šušnjar, Zdravko Pandur, Marin Bačić, David Mijoč","doi":"10.5552/crojfe.2024.2345","DOIUrl":"https://doi.org/10.5552/crojfe.2024.2345","url":null,"abstract":"Labour force represents the sum of human physical and mental abilities used for the production of whatever kind of use values. In forestry, the performance of work operations, especially wood harvesting, represents a high-risk, physically intensive, and professionally very demanding activity, which inevitably requires a qualified and sustainable labour force. Professional, skilful and motivated forestry workers are the basic requirement for efficient forestry operations and make a constituent part of todays sustainable forest management. However, the forestry sector has recently been facing the increasing problem of a shortage of forestry workers i.e. the major challenge of obtaining the necessary labour force. The reasons for this are different demographic, economic, technological and political processes, as well as the specifics of the forestry sector itself. Therefore, in addition to some general indicators of the forestry workforce condition in Europe and worldwide, this paper presents forestry experts' reflections on the future perspectives of forest work in Bosnia and Herzegovina. Special attention is paid to current issues and problems in attaining and ensuring the necessary labour force (attitudes on forestry work and the profession of forestry worker, gravity of the labour shortage, leading causes and reasons for the lack of forestry workers) and to possible measures and instruments important for improving the forestry workforce sustainability (factors for successful recruitment of forestry workers, stronger retention of workers, greater work commitment, general forest management issues affecting workforce sustainability, etc.). The opinions of forestry experts in public and private companies were statistically tested for differences. The aim of the study is to sensibilize the sector and the public on the problems of the labour force in forestry, its condition and status, and to create the basis that can contribute to bettering the status and sustainability of the labour force in forestry.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" December","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and Evaluation of a Felling Head for a Light Forest Crawler","authors":"Christian Knobloch, Jörn Erler, Paul Pfanzelt, Lars Richter","doi":"10.5552/crojfe.2024.2048","DOIUrl":"https://doi.org/10.5552/crojfe.2024.2048","url":null,"abstract":"With motor-manual wood harvesting (by a forest worker with a chainsaw) fatal accidents happen every year when the tree is felled or when parts of the crown fall down. The alternative is to fell trees mechanically using a timber harvester head, which, however, must be brought up to the trees in the forest by means of its crane. With the usual crane reach of 10 m, the harvester needs a system of parallel strip roads with a spacing of 20 m. Furthermore, the harvester needs a dead weight of around 20 tons that compacts the soil. Both consequences increasingly evoke critics. The requirement to fell trees mechanically and to enlarge the distance between the strip roads calls for a solution to fell trees with a small, light machine that can apply its felling tool to the tree in close proximity. Together Pfanzelt Maschinenbau GmbH and the Professorship for Forest Technology of Technische Universität Dresden have run a project for developing a compact, new type of felling head, which is attached to the existing forest crawler »Moritz FR70/75« by means of a short manipulation arm. This head imitates the felling technique, which is applied by a forest worker, in a mechanical way with a high grade of automatization. Even though this machine works with higher system costs, it is significantly faster and more precise than the motor-manual version. The functional principle of the felling head was developed, patented, conceptualized and optimized with the help of prototypes and individual tests at the TU Dresden, Professorship for Forest Technology. After that, it was completely designed, manufactured and automated in terms of control technology by the Pfanzelt company. More than 100 conifers with a felling diameter of up to 50 cm were felled safely and without any problems with the prototype. The possible integration into harvesting processes as well as the effects on the use in the forest stands were analyzed in detail. The project has shown that it is possible to fell trees in a fully mechanized way without danger for the forest worker with a machine that weights roughly a tenth of the dead weight of a conventional harvester.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" April","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Realization of Autonomous Detection, Positioning and Angle Estimation of Harvested Logs","authors":"Songyu Li, Håkan Lideskog","doi":"10.5552/crojfe.2023.2056","DOIUrl":"https://doi.org/10.5552/crojfe.2023.2056","url":null,"abstract":"To further develop forest production, higher automation of forest operations is required. Such endeavour promotes research on unmanned forest machines. Designing unmanned forest machines that exercise forwarding requires an understanding of positioning and angle estimations of logs after cutting and delimbing have been conducted, as support for subsequent crane loading work. This study aims to improve the automation of the forwarding operation and presents a system to realize real-time automatic detection, positioning, and angle estimation of harvested logs implemented on an existing unmanned forest machine experimental platform from the AORO (Arctic Off-Road Robotics) Lab. This system uses ROS as the underlying software architecture and a Zed2 camera and NVIDIA JETSON AGX XAVIER as the imaging sensor and computing platform, respectively, utilizing the YOLOv3 algorithm for real-time object detection. Moreover, the study combines the processing of depth data and depth to spatial transform to realize the calculation of the relative location of the target log related to the camera. On this basis, the angle estimation of the target log is further realized by image processing and color analysis. Finally, the absolute position and log angles are determined by the spatial coordinate transformation of the relative position data. This system was tested and validated using a pre-trained log detector for birch with a mean average precision (mAP) of 80.51%. Log positioning mean error did not exceed 0.27 m and the angle estimation mean error was less than 3 degrees during the tests. This log pose estimation method could encompass one important part of automated forwarding operations.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":"1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41938737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating Productivity of Small-Scale Cable Yarding System Integrated with a Portable Winch","authors":"Emin Akay Abdullah, K. Gümüş, Adil Başaran","doi":"10.5552/crojfe.2023.1957","DOIUrl":"https://doi.org/10.5552/crojfe.2023.1957","url":null,"abstract":"Small-scale forestry operations, which are used in non-industrial and site specific forestry, provide alternative logging methods suitable for precision forestry approach. In this study, a small-scale cable yarding system integrated with a portable winch was considered as alternative timber extraction method compared to a standard tower yarder. It was aimed to evaluate productivity of this yarding method, which was implemented during commercial harvesting activities performed in a 10.74 ha black pine stand located in Bursa province of Turkey. The main factors (i.e. slope, yarding distance, lateral pulling distance, log volume, log length), significantly affecting the productivity, were evaluated based on two slope classes (34–50% and 50–70%) and two yarding distances (100 m and 200 m). The results indicated that the average productivity was 0.95 m3/PMH and 0.90 m3/SMH. It was revealed that the productivity of the small-scale cable yarding decreased as the ground slope and the yarding distance increased. Statistical analysis indicated that there was a significant (p<0.001) relationship between productivity and log volume and length in four applications. On the other hand, it was found that there was a significant (p<0.05) relationship between productivity and lateral pulling distance in only the first application (34–50% slope; 100 m yarding distance). Considering the volume classes of the logs, it was determined that the productivity increased from the low volume class to the high volume class.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49014162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Prototype for Automated Delimitation of Work Cycles from Machine Sensor Data in Cable Yarding Operations","authors":"Thomas Varch, Dennis Malle, Gernot Erber, Christoph Gollob, R. Spinelli, R. Visser, A. Holzinger, K. Stampfer","doi":"10.5552/crojfe.2023.2248","DOIUrl":"https://doi.org/10.5552/crojfe.2023.2248","url":null,"abstract":"The demand for increased efficiency in timber harvesting has traditionally been met by continuous technical improvements in machines and an increase in mechanisation. The use of active and passive sensors on machines enables improvements in aspects such as operational efficiency, fuel consumption and worker safety. Timber harvesting machine manufacturers have used these technologies to improve the maintenance and control of their machines, to select and optimise harvesting techniques and fuel consumption. To a more limited extent, it has also been used to evaluate the time taken to complete tasks. The systematic use of machine sensor data, in a central database or cloud solution is a more recent trend.Machine data is recorded over long periods of time and at high resolution. This data therefore has considerable potential for scientific investigations. For mechanised timber harvesting operations, this could include a better understanding of the interaction between productivity and operational parameters, which first of all requires an efficient determination of cycle time.This study was the first to automatically delimitate tower yarder cycle times from machine sensor data. In addition to machine sensor data, cycle times were collected through a traditional manual time and motion study, and cycle times from both studies were compared to a reference cycle time determined from video footage of the yarder in operation.Based on three days of detailed time study, the total cycle time in the classic manual time (–1.3%) and in the machine sensor data (–1.2%) was only slightly shorter than in the reference study, and the average cycle time did not differ significantly (classic manual time study: –0.08±0.94 min, p=0.997; machine sensor data study: –0.08±0.26 min, p=0.997). However, the accuracy of the machine sensor approach (RMSE=0.92) was more than three times higher than that of the classic manual time study (RMSE=0.27).With the integration of sensors on forestry machines now being commonplace, this study shows that machine sensor data can be reliably interpreted for time study purposes such as machine or system optimisation. This eliminates the need for manual time study, which can be both cumbersome and dependent on the experience of the observer, and allows long term data sets to be obtained and analysed with comparatively little effort. However, a truly automated time study needs to be supplemented with automated determination of and linkage to other operational parameters, such as yarding and lateral yarding distance or load volume.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48007172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of Individual Tree Parameters with Carriage-Based Laser Scanning in Cable Yarding Operations","authors":"Christoph Gollob, Ralf Kraßnitzer, A. Nothdurft, Tim Ritter, Andreas Tockner, Gernot Erber, M. Kühmaier, Ferdinand Hönigsberger, Thomas Varch, Andreas Holzinger, K. Stampfer","doi":"10.5552/crojfe.2023.2252","DOIUrl":"https://doi.org/10.5552/crojfe.2023.2252","url":null,"abstract":"Introduction: Cable yarding is a technology that enables efficient and sustainable use of timber resources in mountainous areas. Carriages as an integral component of cable yarding systems have undergone significant development in recent decades. In addition to mechanical and functional developments, carriages are increasingly used as carrier platforms for various sensors. The goal of this study was to assess the accuracy of individual standing tree and stand variable estimates obtained by a mobile laser scanning system mounted on a cable yarder carriage.Methods: Eight cable corridors were scanned across two forest stands. Four different scan variants were conducted, differing in the movement speed of the carriage and the direction of movement during scanning. An algorithm for tree detection, diameter and height estimation was applied to the 3D datasets and evaluated against manual tree measurements.Results: The analysis of the 3D scans showed that the individual tree parameters strongly depend on the scan variant and the distance of each individual tree to the skyline. This was due to changing 3D point densities and occlusion effects. It turned out that scan variant 1, in which the scan was performed during slow carriage movement downwards and back upwards again, was advantageous. At a distance of 10 m, which is half of the recommended corridor spacing of 20 m for whole tree cable yarding, 95.44% of the trees in stand 1 and 92.16% of the trees in stand 2 could be detected automatically. The corresponding root mean sqare errors of the diameter at breast height estimatimations were 1.59 cm and 2.23 cm, respectively. The root mean square errors of the height measurements were 2.94 m and 4.63 m.Conclusions: The results of this study can help to further advance the digitization of cable yarding and timber flow from the standing tree to the sawmill. However, this requires further development steps in cable yarder, carriage, and laserscanner technology. Furthermore, there is also a need for more efficient software routines to take the next steps towards precision forestry.","PeriodicalId":55204,"journal":{"name":"Croatian Journal of Forest Engineering","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48823586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}