Petru Boghean1 and Alexandra Pavel1
1
National Institute of Wood, Bucharest, Romania.
Abstract
The wide variety of forest lands in Romania results in a relatively rich level of experience concerning forest technologies, machines and equipment used, and transport technology.
Forest roads open up the forest lands, creating more efficient accessibility where the gains of science and technology can be gainfully applied. The extension of forest roads made possible the development of the irregular shelterwood system, considered the most efficient of the ecoforestry technological systems. Long-term management of the forest has to be based on principles ensuring natural regeneration, sanitary cuttings, minimal damage and valuable bioproduction.
The variants and influences of forest road networks upon harvesting technologies and consequences are analysed and briefly presented in this paper related to the national level and local conditions in Romania.
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Forest roads are essential not only for timber harvesting but also to provide access for forest management and control purposes.
It should be emphasized that their sustainable development has to be considered strictly connected to an efficient transport and reliable access to the forest.
The forest road network in Romania amounts to 29 743 km, 90 percent inside the forest. Under these conditions forest road density amounts to 6.2 m/ha. Expressed in terms of forest percentage opened by roads, this corresponds to an access of 65 percent from forest land.
The average extraction distance for forest road areas is relatively high (1.2-1.4 km) with direct impact on the technologies used and logging costs.
Considering this situation when the forest road density is lower than normal there are:
· overcutting of areas with access roads,
· limitation of tending and sanitary fellings,
· preferential utilization of treatments based on concentrated extractions,
· high costs of production, labour, materials, and energy for operations in landings,
· major restrictions to the profitability of all forest products and resources.
The above-mentioned disadvantages could be corrected by using appropriate technologies and transport means, which would allow efficient conditions to adopt forest regeneration and protection measures.
At present and within the foreseeable future, harvesting technologies are directly involved with technical, economic, social and forestry activities, required by environmentally sound principles.
Lack of an appropriate density of forest roads has caused inefficient solutions either for tending and sanitary operations and proper logging.
Concerning the logging sector, it is worth noting wood extraction on long distances by means of
· tractors, 1200-1800 m;
· cableways, 1500 - 2000 m;
· draught animals, 300 - 500 m
damage the soil, useful seedlings and stand trees, more than normal values. An important part of the wood is abandoned, managed insufficiently or used too late in the economic circuit (about 2 000 000 ha).
Logging technology, extraction system and wood transport are among the important techno-economic factors that affect the degree of development of a road network.
Each logging technology has certain specific methods and extraction means, which have a particular direct effect on the forest.
The material to be transported in various forms and dimensions (full trees, parts of trees, stems, masts, finished assortments, branches) requires certain overall dimensions, constructions solutions, motor power, loading/unloading system, which determine the dimension of the roads. At the same time, landings where logs are delivered, sorted, and temporarily stored during the extraction process must be taken into consideration.
In Romania over time permanent and temporary transport installations have been created to promote improved standards of forest utilization.
Forest roads, which have been properly designed and constructed according to environmentally sound engineering practices, must minimize the average extraction distance and provide low-cost access to the forest.
The uniform distribution of a forest road network must take into account land topography, the dimensions of areas to be logged and the stand location. The result to be achieved is not only to keep the average extraction distance within restricted limits but also to use the same type of machinery and equipment by applying standard logging methods.
The logging operations technology was developed in this framework with effective influences upon the road network structure and strategy. Within restricted periods of time (1960-1975, 1975-1990, and 1990-1995) when the road density was not essentially changed, the logging methods were mainly
· rough conversion even at the felling place,
· stem and mast logging,
· full or partial tree logging in different combinations.
Logging technologies were developed along with the forest roads to some extent but were mainly affected by the improvements in forestry operations or by the economic policy of our country.
Figure 1. Wood harvesting technologies practised during 1960 - 1995
In Romania wood extraction techniques were connected with the development of the forest road network.
The investment required for forest roads and their location are the main factors in the extraction planning. It should be noted that when planning forest roads, also wood extraction methods must be considered.
In 1995 transport cost per cm over long distances was twice lower than if tractors or cableways had been used and 12 times lower than if draught animals had been employed. This, as well as high fuel consumption and low labour productivity, is the main reason for the real necessity to increase the road density.
Recent data indicate that about 38.9 percent of the total logging cost depend on the extraction system, regardless of the method. The difference is very low, 2.8 percent, between the tractor or cableways system.
The solutions to wood extraction in Romania take into account the various physical-geographical conditions of our country and try to make profitable the relief aspects, focus on achieving, as much as possible, technical and economic efficiency within the existing road network. In addition, the installation and machinery design as well as the planning and development of extraction processes made progress towards optimum standards of forest roads. This achievement is naturally slower.
The road network and the logging technology affect to a great extent the structure and the characteristics of the machinery system, especially of that intended for extraction. In the case of a low density of forest roads the cableway method is most used.
For the first landings (1950) set up in Romania, cableway installations (Valteline, Maneciu) have been erected at distances longer than 2 km.
Depending on the length of the forest roads, other types of cableways are used: FP-2 from 500 m up to 2 000 m, FPU-500 up to 500 m. Recently, the extraction distance of FP-2 was reduced to 1500 m.
The main characteristic of the cableways is the distance between the spar and the anchor trees. The smaller the distance, the more efficient is the cableway. Considering the existing road density, the type FP-2 and FPU-500 are used at the maximum distance.
The results were not as expected when we tried to use an installation with cable and support for a 400 m distance extraction (FUMO-403).
The technical means of the extraction lines are directly responsible for the operations and their efficiency, including transport.
To establish the extraction lines it is necessary to take into account several factors with their individual or combined influences.
The natural and techno-economic conditions of Romania require combining frequently the tractor with the cableway system.
The mountainous relief configuration, mostly stretched (61%) imposes the choice between two types of equipment and it is sometimes difficult to decide which one to use.
For the same average extraction distance, when forest roads exist, the area that can be developed is 2-3 times larger than when using cableways. Economically it is a complex operation to adopt the appropriate solution, but it is considered that the cableway is most efficient in the case of long distances and is suitable to the requirements of forestry treatment.
When articulated tractors are used, the most efficient skidding distance is between 600 m and 800 m. When increasing the distance, the productivity decreases significantly.
As a rule, the planning of forest truck roads has to consider also the possibility of creating roads for tractor skidding within efficient distance limits.
Skidders (TAF-650, TAF-450, U-650) because of their construction system and technical parameters are appropriate to the characteristics of logging and existing forest roads in Romania.
The most common form of log transport from the forest is by road, using logging trucks (91%). This type of transport was stimulated in Romania by several factors: the relatively low cost of roads compared with the railway system, access to energy sources, high speed of operation compared to other transport means.
The cost per km of a forest road and the price of fuel are very high. Individual fuel consumption had to be reduced. One of the ways to obtain it, is to use very high capacity roads, which tend to cause great problems in terms of road maintenance and repair.
The main types of roads used in the logging sector are 14 t truck-platforms, (32%), 20 t trucks and trailers (30%), 16 t trucks and trailers (19%).
In the future priorities areas are the modernization of roads, furnishing them with hydraulic cranes and the improvement of the superstructure.
Experts should design new transport means and truck systems with increased motor power and capacity.
Considering the forest road network in Romania and its influence upon rational logging methods and technologies the following conclusions can be presented:
· The forest road density in Romania should be brought to an optimum level - at a first stage to 13.3 m/ha, to be increased later. The present density does not ensure efficient conditions for sustainable management of forest and forest products.· Long average distances in logging increase production costs and limit the utilization of all wood resources.
· The use of extraction equipment, especially cableways, over long distances can cause environmental problems.
· Tractors and cableways, which are considered as the main equipment in extraction, lose efficiency if used over long distances.
· The average extraction distance is 1.2-1.4 km. Logging activities are difficult due to the discontinuous flow of operation and the type of equipment used. Cableways are most suitable compared to the tractors, and draught animals are better than other non-mechanized system.
· The transport means need improving in terms of typo-dimensional diversification and should be equipped with loading/unloading devices, necessary for modern sorting and transport technologies.
Environmentally, the transport of logs from the landing to the processing facilities or other final destination is a relatively low-impact operation. Most of the direct impact is caused by the transport infrastructure (usually roads) rather than by the transport operations.
Taking into account the existing forest road network, the logging and wood transport equipment and machinery, the Romanian specialists concerned with these matters propose to discuss the following questions with the specialists from other countries who have long and rich experience.
· What are the limits of forest roads density that could avoid the risk of environmental impact?· Are there solutions for steep roads to reduce the average extraction distance in environmentally sound conditions?
· What is most damaging for the forest - roads or complex logging equipment?
· In order to observe environmental conditions and to render the operation profitable, what is a suitable proportion between the wood extracted and that left in the forest? Is it efficient to build forest roads?
