Current issue: 58(5)
Articles containing the keyword 'transportation'
Category : Article
Light and economic FM-CW radar has been developed for controlling the bearing capacity of ice roads and landings on ice used for timber transportation and storage of timber in Finland. It was tested on natural ice and ice roads of three lakes in Southern Finland and one location on sea on the southren coast of Finland (a total of 166 observations). Ice thickness varied from 0 to 100 cm. Correlation coefficient between auger and radar measured ice thickness was r=0.99 and absolute error varied from -10 to +7 cm. The quality of ice had no influence, but by improving the interpretation of results, also the quality factors might be detected.
The PDF includes a summary in Finnish.
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Saarilahti,
E-mail:
ms@mm.unknown
The paper deals with the optimization of roundwood transport in cases where many destinations for it exist and where several means of transport are available. It is also understood that the capacities of the factories to which wood is transported can be used at varying degree. A model was developed for a case such as Finland which sells most of its products abroad.
In the above case, the optimization of roundwood transport does not necessarily mean minimization of transport costs. What is aimed at is to obtain, by using different combinations (mill destinations and the media of transport) the maximum difference between the allowable cut (calculated) and real (actual) transport costs.
The PDF includes a summary in English.
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Roitto,
E-mail:
yr@mm.unknown
The goal of this study was to develop a mathematical model for determination of the optimal winching distance in different conditions as based on harvesting costs. In the thinned forest the strip roads are parallel and the winching routes perpendicularly to them. A directed felling of trees is used so that it is easy to make loads to be winched. The stems can also be prepared to timber assortments on the stump area and gathered to loads for skidding alongside the winching routes.
After winching the timber is transported using a forwarder mowing on the strip roads. If the stems have not been bucked in the forests, they are to be prepared to timber assortments before the following transportation, because the problem of turning whole stems in a thinned forest has not yet been solved.
In the mathematical model the formation of the costs was described using 18 variables of which 15 had an effect on the optimum winching distance. Some empirical values were estimated concerning these variables, and the corresponding optimum winching distance were computed. The optimum was mainly determined by the quantity of timber harvested per unit area, the size of the winching load, the regression coefficient of the times which were depended on the winching distance.
According to the model, the deviation from optimum winching distance does not cause a very great change in the analysed total costs. When the winching distance is longer, the increase of the costs is smaller than if it is shorter than optimum. In general, the increase of the costs was so small that in practice one obviously can be satisfied with rather approximate methods in determining the suitable winching distance.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The purpose of this study was to explain whether it is possible to affect, in practical working site conditions, by means of logging waste on the strip road, the depth of the track which is formed in terrain transportation and the injuries of the growing stand. Five 20 m long investigation areas with logging waste and five similar areas without logging waste were arranged on one strip road at Teisko logging site in Southern Finland. The logging waste layer was mainly Norway spruce and 10–15 cm thick. A KL–836 B forwarder was used. The type of soil was loam.
The logging waste affected the depth of the track only by decreasing the wear of humus layer. Even decreasing effect of logging waste on the injuries in the growing stand was minor. At Kitee working site in Eastern Finland strip roads were studied. The type of soil was thick, rather mouldered peat. The thickness of logging waste was 3–4 times greater than in Teisko, mainly spruce. A Volvo Nalle SM 460 forwarder was used. The effect of the logging waste on the depth of the tracks was clearly to be noticed. On basis of the appearance of the tracks one could assume that the difference was due to different wear of the humus, and not so much due to the quantity of logging waste that improves the carrying capacity of terrain.
In some extent logging waste was also found to affect the amount and quality of tree injuries. In practical working conditions, the importance might be small, since in the experiments an unrealistically great amount of logging waste was used.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
Measurement of timber in a vehicle load or in a bundle is best performed at the mill where the measuring of large quantities can be mechanized and sampling is possible. Load measurement methods include calculation of the number of units, measurement of pile volume, weight scaling and determination of solid content in accordance with Archimedes principle by immersion in water. For some timber assortments, load measurement is sufficiently accurate and suitable unit of measure. The accuracy of load measurement can be increased or the result can be converted by sampling to a more appropriate unit of measure.
In load sampling measurement, a sample is taken from the population, and the desired more accurate measurement is made from the sample. The basic measurement for the whole population can be converted into the more accurate measuring unit by means of the ratio between it and the basic measure. Unit, pile and weight sampling can be used. The aim for pulpwood is to calculate the dry matter content without bark, which means that the amount of bark and the dry weight of wood must be determined by sampling.
The size of the sample depends on size of the population, variation of the ratio between the loads, and the accuracy required. As the quantity of wood to be measured decreases, sampling measurement will reduce the measuring costs by up to 80%. In addition, there is saving in costs by rationalization.
The PDF includes a summary in English.
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Leinonen,
E-mail:
el@mm.unknown
- Rikkonen, E-mail: pr@mm.unknown
The purpose of this study was to answer questions concerning the basic information in planning of timber harvesting, how this information has to be handled, and how the planning of logging has to be combined with other forest management planning.
A deductive research method was used. By analysing a logging plan, prepared for a certain forest area, general conclusions were reached. To prepare the logging plan in connection with the forest management plan, the following information was found to be necessary: boundaries of the area, extent and ownership of the planned area, maps including information of the location of the timber and the conditions for transportation, road network and a reliable picture of the difficulty of the forest terrain.
Based on the material of the present timber harvesting methods it will be possible to predict the logging methods which will be applicable in the near future. The object to be planned has to be divided to operation areas. The amount of manpower and equipment needed can be estimated for each phase of the timber harvesting chain on the basis of the information calculated in this manner. Investments to machines and basic improvement works have to be planned before the effect of planning can be calculated in the logging costs, which are to be minimized. Due to the rapid development of the field, the handling of the material in connection with a forest management plan has to be left partly unfinished since the development of future logging methods cannot be reliably predicted.
The PDF includes a summary in English.
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Haarlaa,
E-mail:
rh@mm.unknown
The wages of logging and haulage has been dependent on the decisions of foremen. The aim of this study was to provide better insight on how working conditions in a logging site affect productivity of the work. Six working sites operated by Forest Service, Veitsiluoto Oy and Kemi Oy in the communes of Salla, Muonio and Kolari in Lapland were studied. The forests in the area were mostly Scots pine (Pinus sylvestris L.).
The effect of average volume of the stems, the average daily haulage over distances of various lengths, density of the stand and shape of the stem on effectivity was calculated. The size of the team was of considerable importance to the felling and haulage result in the Northern Finland where the feller assists in loading of the logs. One of the aims of the study was to find out what size of team is most advantageous for each haulage distance. The results show the optimum distance of haulage for teams of different sizes.
The article includes a summary in English.
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Maliniemi,
E-mail:
em@mm.unknown
The government of Finland appointed in1949 a committee to draft a program to promote forestry and increase the production of forests in the immediate future. The committee regarded promotion of transportation of roundwood and fuel wood as the most urgent question of the assignment. A separate committee was assigned to give a report on floating.
The report gives a summary of timber transportation facilities. The importance of land transport, especially truck transport, has grown. This has influenced other means of long-distance transport, such as railways and floating. Building of truck roads can bring large areas of presently unaccessible forests accessible for forest industry.
The committee suggest improvements in road legislation. Improvements needed in the road system for better timber transport facilities are outlined. The committee gives a detailed list of roads, compiled by area. The total length of forest roads to be constructed is 5,584 km, and the estimated cost 6,702 million marks. Railroads would be built 1,453 km at the cost of 35,745 million marks.
The article includes an abstract in English.
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
Floating channels of Northern Finland have been unable to fulfill all the needs of wood transportation of the area. This presentation presents diferent ways to improve the efficiency of floating by improving working methods and the channels, and thus decreasing costs of wood transportation.
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Kivelä,
E-mail:
ak@mm.unknown
Silva Fennica Issue 64 includes presentations held in 1947 in the third professional development courses, arranged for foresters working in the public administration. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service. Two of the presentations were published in other publications than Silva Fennica.
This presentation describes budgeting of costs of delivery loggings, which have been at times underestimated in the practical forestry in the state forests.
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Anttila,
E-mail:
aa@mm.unknown
Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation discusses the development of road and path network in state lands in Finland. The speaker wants to stress the need for systematic expansion of the road network, which would serve several demands in forestry.
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Ahola,
E-mail:
va@mm.unknown
Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes the history of road transport of timber in Finland and discusses its significance and potential to forestry in the state forests.
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Seppänen,
E-mail:
os@mm.unknown
Category : Article
Seasonal variation in the sawmill industry of Finland was studied in an investigation based on questionnaires answered by a random sample of sawmills concerning the time period of 1958-1960. The method is described in detail in a separate article in Acta Forestalia Fennica issue 75 no. 1.
The seasonal variations in purchase of roundwood was largest in big sawmills, which purchase the main part of the timber as standing sales and buy most of the wood from the State Forest auctions at the end of September. Also, they can afford to reserve their material earlier than the smaller companies. The saw logs are mainly felled in the winter in Finland because the climatic conditions and availability of labour are best at that time. Small sawmills begin fellings a little earlier than the larger ones.
In long-transport of timber the proportion of floating decreased from 47% in 1958 to 38% in 1960. At the same time, proportion of truck transport increased from 48% to 55%. Small sawmills use almost exclusively land transport. They received almost three-fourths of their logs between January and May, because the sawing is concentrated in the first half of the year. Therefore, floating does not suit for their transport method. The larger the sawmill, the later is the seasonal peak of log deliveries. The output of the big sawmills is distributed more evenly thoughout the year. The smaller the sawmill, the quicker is the turnover of raw material and the smaller the sawlog inventories.
The seasonal variation in output is sharper at small sawmills where sawing is concentrated in the first half of the year. The seasonal peak of the early spring is due to the aim at getting the sawn wood to dry early enough for shipments in the summer. Air drying takes an average of 4 ½ months. Kiln drying is more common at the larger sawmills, and gives them more flexibility. Due to the large seasonal variation in operation, the capacity of the small mills is poorly utilized. Domestic sales of sawn wood levels up the seasonality of the deliveries. Export sales are concentrated at the end and turn of the year. Also, the seasonal peak of expenditure occurs in the winter, but that of income in the summer.
The PDF includes a summary in English.
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Ervasti,
E-mail:
se@mm.unknown
In Finland roundwood is floated either privately or co-operatively. In the later, a co-operative floating association is established to operate floating. The association is compulsory association of those enterprises who want to have wood floated along the floating routes of the area. It is favoured when the number of enterprises and the wood to be floated is large. In addition, costs are lower than in private floating.
Floating in Lake Saimaa area in Central Finland can be divided into Iso-Saimaa, where floating is private, and into Saimaa Water System, where floating is operated by a co-operative floating association. It has been suggested that adoption of co-operative floating in Iso-Saimaa would be to the common interest. This study aimed at finding out if co-operative floating influences the transport costs, and if co-operative floating increases competition of roundwood by forest industry companies.
According to the study, the costs of most enterprises would decrease. The total decrease in costs would amount to 65 million Finnish marks annually, about 20% less than the present costs. The change of organization would not alter the competitive relationship in buying roundwood. On the other hand, it would seem that co-operative floating would be less flexible than private floating. The management of a large organization, whose effective operation time would cover only a part of the year, would meet with some difficulties. Also, co-operative floating would reduce competition among enterprises.
The PDF includes a summary in English.
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Roitto,
E-mail:
yr@mm.unknown
Central Association of Finnish Forest Industries decided in 1953 to begin collecting annual statistics of timber transportation of its members. The survey of members covers almost 97% of the timber transportations of the member companies, which have production over 1,000 cu ft. In all 79 companies answered the survey. Their total timber transportation was 166,4 million cu ft in 1952.
The long-distance transportation of saw logs by horse transport directly to the mill or other such location was 1,297 cu ft, by truck transport 42,644 cu ft, by rail transport 6,707 cu ft, and by water transport 115,789 cu ft. The average transportation distance was for horse transport 2.4 km, truck transport 27 km, rail transport 224 km and water transport 209 km.
The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.
The PDF includes a summary in German.
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Lindfors,
E-mail:
jl@mm.unknown
The costs of floating have increased by about 20-fold after the Second World War in Finland, which has raised concerns in the forest sector. At the same time, the costs of road transport have increased by 16% and costs of rail transport by 15%. Floating has been replaced mainly by road transport in transport of roundwood, especially near the factories. This development is likely to continue as new roads are built and the truck fleet develops.
In spite of the changes in timber transportation, floating was still the most common way of transporting roundwood in 1952: 69% of saw logs, 53% of veneer timber, 42% of domestic pulp wood, 14% of exported pulp wood and mining timber and 14% of firewood was transported by a water route. There are several ways to improve the efficiency of floating and decrease its costs. This can be achieved in two ways. First, using modern technology, such as tugboats, bundlers and other equipment, and second, improving the operation and co-operation between different actors.
The PDF includes a summary in German.
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Stolpe,
E-mail:
ns@mm.unknown
About 17.5% of forest lands of Finland is situated around the river and lake system of Lake Saimaa. Furthermore, the growth of the forests of the area correspond about 25% of the total growth of forests in Finland. The watersystem is one of the most important portages of roundwood in the country. It consists 11,000 km of floating channels, 2,000 km of which suit for floating in bundles. Annually 30-35 million cu ft of saw logs, 7 million cu ft of veneer timber and 2,5-3 million cu ft of pulp wood is floated in the area.
Even if the water system at present still suits well for floating, there are many opportunities for development, which would improve its competitiveness against other modes of transport. Several different sites where building of floating channels or improving the floatways are needed are described in the article.
The PDF includes a summary in German.
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Roitto,
E-mail:
wr@mm.unknown
In the present investigation, the problems connected to demand of firewood are dealt with by studying the fuel markets of the three biggest towns in Finland – Helsinki, Turku and Tampere as well as those of Vaasa. The purpose of the investigation was to study the firewood supply areas in two time periods, in 1933-1939 and in 1945-1947, after the Second World War.
Railway and shipping were the most important ways for transporting firewood in 1933-1939. Towards the end of the period, road transport increased especially in Turku and in Vaasa. In 1945-47 almost 90% of the firewood transported to Helsinki, 60% to Tampere and Turku, and over 50% of the firewood transpors to Vaasa were carried by rail. One factor supporting rail transport was that the tariff policy of the State Railways gave preference to firewood transports.
The supply areas increased markedly from 1933-1939 to 1945-1947. Supply of firewood near the towns in the southern, southwestern and western parts of the country was small. Also, pulp industry began to use small-sized timber in 1930s, which increased competition of the wood. Coal and coke began to replace firewood in the 30s, but their use decreased during and after the war due to supply shortage.
The PDF includes a summary in English.
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Holopainen,
E-mail:
vh@mm.unknown
In Finland, transportation of wood by vessels has decreased, but is still an important mode of transport especially for firewood. In 1941-1947, nearly 25% of the firewood procured by the State Fuel Board was transported by vessels. This investigation concentrates on loading of wood into barges, since the share of wages of total expenses is greatest in this phase. The loading work amounts to nearly 40% of the total wages.
Two methods of loading barges are used in Finland: loading from the shore and truck loading. This study concentrates on the more common method, loading from the shore. A time study was conducted on the different stages of loading and piling wood into barges, most of which is done by hand. Most time-consuming part of the work is transporting the logs to the barge with a wheelbarrow, comprising over 40% of the working time. Time required for loading firewood is almost twice as much as loading pulp wood. Recommendations for loading places and organization of work are given in the article to improve the efficiency of the work.
The PDF includes a summary in English.
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Heiskanen,
E-mail:
vh@mm.unknown
The numerous waterways have promoted the development of forest industry in Finland by offering an easy way to transport timber almost in the whole country. Floating associations arrange the floating for its members. This study, accomplished in the Forest Research Institute, compiles the statistics of the different associations in 1922‒1927. The volume of timber transported by the floating associations increased by 40% during the 6-year period, reaching 10.5 million m3 in 1927. The increase has been supported by the number of collectively used floating channels. The number of the floating associations increase from 17 to 26 and the length of the floating channels used by them to 8,300 km in 1922‒1927. About 70‒80% of the transported timber was logs and the 20‒30% small timber. Floated timber comprised 70-80% of the all roundwood used in the forest industry in Finland at the time. Majority of the logs were softwood.
The PDF includes a summary in German.
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Sierla,
E-mail:
vs@mm.unknown
The aim of the study was to determine how timber truck transport business succeeds in the competition within its sector, and the effect it has on profitability structure of the sector. Furthermore, strategic groups were looked at in depth, as well as the competitive strategies of the most successful companies and groups of companies. The theoretical competitive strategy was operationalized.
A total of 53 timber truck transport entrepreneurs were interviewed. The average age of the entrepreneurs was 51 years. Of the businesses, 35% were partnership companies, 6% open companies, and 59% self-employed. The business owned an average 1.5 trucks, and at the time of interviewing their average age was four years. Nearly nine out of ten entrepreneurs had no schooling for the line of business, and four out of five had no short-term training. The attitude of the timber truckers toward their activities was more like that of self-employed persons than that of entrepreneurs. A total of 61.5% of them reporter that they carried on entrepreneurship simply to assure themselves a job.
The operational profitability of the sector has been good in the years 1984 to 1990, and the business profitability fairly good. The median equity ratio in the sector has remained at about 20% and the ratio of debts to turnover about 40%. The sector has been more profitable than forest machine contracting primarily due to the barriers to entry into the sector.
Cluster analysis, using Ward’s method, was used for seeking out strategic groups. The lengths of the customer relationships proved a significant barrier to mobility. The most successful business used the competitive strategy of cost weighted focussing. This was done through optimization of the capacity utilization rate and through choice of correct customers. The strategic position for successful business was judged to be good in the future. Success in the future will require above all activeness and innovation ability.
The PDF includes a summary in English.
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Mäkinen,
E-mail:
pm@mm.unknown
The transport unit in roundwood towing on Lake Iso-Saimaa in Central Finland comprises a tug and a raft of bundled wood with a towline between them. There are several factors influencing the economic size of the transport unit in roundwood towing. These are changing with the enterprises and along with general developments. In this paper these factors or factor groups are seen from the point of view of the enterprise. The main question is to determine the most economic combination of tug and raft size.
From the point of view of the towing enterprises the unit costs of transport are the most decisive factor. Both the size of the raft as well as the power of the tug influence strongly the unit costs. As a long-term goal a raft of about 35,000 m3 and a tug of 550 kW or more is considered to be advisable. The width of channels and sounds then allow a free passage for rafts being 36–40 m wide.
The PDF includes a summary in Finnish and in French.
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Roitto,
E-mail:
yr@mm.unknown
The first part of the study includes a summary of conclusions from five earlier reports dealing with terrain transportation costs, effect of terrain, load, snow and additional machine components on the mobility of forest tractors, and the distance a vehicle has to move in forest transportation of timber. In the second part of the study the effect of these separate factors on the transport output have been analysed on the basis of simulating a transportation of 3,000 loads by computer.
It was concluded that no specific terrain factor had a dominating effect on any component of the forwarding output. However, many terrain-factor combinations with a nonsignificant effect on the mobility and also on the forwarding output were identified. The most significant factors affecting the output were the size of load and the distance driven during the cycle.
The PDF includes a summary in Finnish.
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Haarlaa,
E-mail:
rh@mm.unknown
The purpose of this study was to build a mathematic predictive model for the formation of injuries and to try its usability in predicting. The empirical data consisted of 24 thinning sites, which were situated mainly in forests owned by forestry companies. The timber was made by strip roads. The terrain transportation of timber was carried out by forwarders or by agricultural tractor-trailer combinations.
The model has been compiled by multiple regression analysis. The predictive model has been interpreted so that the formation of injuries is, for one part, dependent of the number of trees exposed to damages, and, on the other hand, on the factors influencing the probability of injuries, the possibility for this existing. The number of trees exposed to injuries is dependent on the density of strip roads and on the amount of standing timber left after logging. The probability of injuries is influenced by the quality of the standing timber, the type of soil and the intensity of the timber harvesting process.
The predictive model has been interpreted in similar way as the number of injured trees. The possibility of formation of injuries is mainly affected by the length of strip roads and the amount of the standing timber. The probability of injuries is influenced, for the part of the number of root injuries by the strength of the soil type, and probably also by transportation equipment. For the amount of stem injuries no valid predictive equation was found in this study.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The present paper presents a study on the works of ancient writers that deal with trees, forests and the use of forests before the time of actual forest sciences. The work describes the development of knowledge pertaining to the forest and trees and the progress made on utilizing them. This second part of a series of two articles is concerned with logging, transportation and trade of timber, as well as procurement and trade of other forest products. These activities have been practiced as long as the history of mankind is known.
The article introduces the most important ancient written sources from the standpoint of the subject of the article, and related modern literature. The second part describes the texts concerning felling and primary conversion, and skidding and transportation. The third part concentrates on timber trade, and the fourth on the procurement and trade of other forest products.
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Makkonen,
E-mail:
om@mm.unknown
Category : Research article
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Karttunen,
Lappeenranta University of Technology, LUT Savo Sustainable Technologies, Sammonkatu 12, FI-50130 Mikkeli, Finland
E-mail:
kalle.karttunen@lut.fi
- Lättilä, Lappeenranta University of Technology, LUT Savo Sustainable Technologies, Sammonkatu 12, FI-50130 Mikkeli, Finland E-mail: lauri.lattila@lut.fi
- Korpinen, Lappeenranta University of Technology, LUT Savo Sustainable Technologies, Sammonkatu 12, FI-50130 Mikkeli, Finland E-mail: olli-jussi.korpinen@lut.fi
- Ranta, Lappeenranta University of Technology, LUT Savo Sustainable Technologies, Sammonkatu 12, FI-50130 Mikkeli, Finland E-mail: tapio.ranta@lut.fi
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Nurminen,
Metsätoimisto Tuomo Nurminen, Joensuuntie 5 B 8, FI-41800 Korpilahti, Finland
E-mail:
tn@nn.fi
- Korpunen, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail: hk@nn.fi
- Uusitalo, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail: ju@nn.fi
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Muinonen,
Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland
E-mail:
eero.muinonen@metla.fi
Category : Review article
Our research aimed to quantify and evaluate the stress loading of drivers by monitoring the loading of the radial extensor muscle at the wrist joint (musculus extensor carpi radialis) when they drove different types of timber trucks. We monitored changes in the electric potential of skeletal muscles with electromyographic measurements and measurements of changes of heart rate using the Biofeedback 2000 x-pert device. The drivers were observed throughout their work shifts during normal operation of logging trucks and logging trucks with trailers. As a reference, muscle load was measured when driving a passenger car. We evaluated the normality of the measured data and obtained descriptive statistics from the individual measurements. The differences in stress load associated with driving the different types of vehicles increased whilst driving on lower-class roads. Results showed a high stress load for drivers of loaded vehicles when driving on narrow roads. It was more challenging to control a loaded logging truck with a trailer than driving a logging truck, with the difference in muscular loading reaching 22.5%. Driving a logging truck with a trailer produced 46.5% more muscle loading compared to driving a loaded passenger car. For preventive health and safety reasons, it would be reasonable to alternate between drivers when operating various vehicles, thus minimizing the development of possible health issues.
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Škvor,
Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic
https://orcid.org/0000-0001-7540-4761
E-mail:
skvorp@fld.czu.cz
- Jankovský, Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic E-mail: jankovskym@fld.czu.cz
- Natov, Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic E-mail: natov@fld.czu.cz
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Dvořák,
Department of Forestry Technologies and Construction, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6 - Suchdol, Czech Republic
https://orcid.org/0000-0002-5986-8002
E-mail:
dvorakj@fld.czu.cz
