Volume 10, numéro 2, july 1999

EN :

The availability and employment potential of doctoral graduates in forest engineering and forest operations across North America is explored in this paper. Past graduation rates, along with current and future employer needs for these graduates were examined through a survey of University-based programs, private companies, and public agencies. The survey suggests that graduation rates for doctoral students are low across North America. Currently, academic openings exist at several Universities and suitable candidates for these positions are not currently available. The survey showed that only half of the students who graduated in the past ten years pursued an academic career after graduation. Based on noted graduation rates, the need for qualified doctoral graduates will steadily increase at many University-based programs.

Survey results of companies and public agencies suggest that the predominant public employer for graduates over the last ten years was the USDA Forest Service, although current attitudes within this agency may limit future employment opportunities. Private companies provide some opportunity for additional employment, although only the largest forest product companies seem willing to hire doctoral graduates. In this survey, only three of the surveyed companies had employees with a doctorate in forest operations or forest engineering.

EN :

This article discusses the logging system where the logs are made at the stump from a harvester and carried to the landing by a forwarder. The focus is on Sweden, yet with international outlooks. Trends in forestry in the last decades are described and used to envision the next decade. In our analysis we consider the call for sustainable forest management, the demand and supply on the wood market, system productivity and utilisation, as well as operational organisation, operator education, health and safety and technical development.

A comparison is made between three mechanised logging methods as well as between three different forest worker education systems. Hindrances found when introducing cut-to-length are operator education, work crew organisation, supply of maintenance service and capital bound in other logging systems.

The trend towards purpose built harvesters is discussed. The possibilities following advanced electrohydraulics and GPS/GIS are discussed regarding machine control, maintenance, operational planning and supervision.

EN :

This paper attempts to review briefly in broad terms the need for researchers and managers of forestry operations to collate their respective knowledge and experience in order to assist the process of designing appropriate inventory, modelling and auditing systems for planning, controlling and reporting operational performance responsibly and effectively. The approach taken here is to outline a relevant philosophy, supported by a few examples regarded as typical of what is envisaged. The aim is not to focus on one particular situation, but to emphasise crucial aspects in general of: (i) multi-resource, pre-harvest inventory (ii) integrated market-led strategic, tactical and operational modelling; and (iii) developing and implementing routine procedures to monitor, control and audit outcomes, so as to provide ecosystem accountability. Knowledge on how to proceed in principle is widely available, but there is still apparent resistance to adopting worthwhile technological improvements routinely. Some few suggestions are given on how forest management pertaining to the above three aspects could be beneficially redirected.

EN :

This paper on the future of Finnish wood harvesting is based on a Delfoi interview study and on the stage of the life cycle of different technologies or methods. Personal views of the author are also included.

EN :

The purpose of this study was to ascribe attributes to forest access roads, to allow for estimation of their serviceability on the basis of their current condition. The approach estimates the quantity of timber that may be hauled through without critically damaging the flexible pavements. Seventy-two roads were classified on the basis of their surface conditions, subgrade material, and surface deflection as the strength parameter, for 40 and 60 t Gross Vehicle Weight. Using non-parametric statistical techniques, it was found that the surface quality of pavements was largely dependent on drainage conditions (coefficient of determination r2 = 0.84), and that a strong relationship (r2 = 0.90) also existed between drainage and the number of potholes. Pavements with peat subgrades were found to exhibit significantly higher critical deflections (5.6 mm) than pavements with mineral subgrades (1 mm), coupled with their inherent variability, it is arguable that visual classification may not be suitable for such pavements. On the basis of these results, the serviceability of individual roads, in Equivalent Standard Axle Loads (ESAL) was estimated. Potential pavement damage by a standard 6 axle timber haulage truck, of 40 t Gross Vehicle Weight, with a payload of 27 t, was evaluated to be triple that due to a standard axle (8.16 t). Increasing the payload by about 10%, increased the ESAL required to transport a unit volume of timber, hence potential pavement damage, by 20%. Consequently, a significant reduction in the serviceability of forest access roads may be incurred by small overload margins that are usually ignored.

EN :

To compare the performance and cost of two machine types, a time study of single-grip harvesters (SGH) and double-grip harvesters (DGH) was conducted in the final cutting of three shelterwood stands in central parts of Sweden. A randomized block design was used with one block in each stand and the treatments SGH and DGH, respectively. The stands were characterized by dense to relatively dense advanced regeneration under approximately 200 trees/ha. No significant differences were found in mean harvesting time between SGH and DGH or between stands. Fewer trees, but approximately the same volume per hour, were harvested when shelterwood stands were cut as compared with clear– cutting of ordinary stands. Despite few stems per hectare and the dense regeneration hindering the operator's field of view, final cutting was done with fairly high productivity (15.9– 34.0 m3/E15-h) and a low harvesting cost (2.7 – 6.0 USD/m3). It was concluded that both machine types gave acceptable results regarding cost and productivity. The SGH could be recommended as a good choice in general due to the low cost per machine hour as compared with the DGH, while the properties of the DGH would be beneficial in shelterwood stands with a large proportion of trees with large diameter (e.g. >7 cm) branches.

EN :

The purpose of this study was to develop the k-nearest-neighbour method as a wood procurement planning tool. Traditionally, sampling measurement of standing trees has been used to obtain advance information on marked stands. In this study, key figures such as sawtimber/pulpwood ratio in pine and spruce stands, diameter and height distribution in spruce stands, diameter and quality distribution in pine stands, and quality distribution by diameter classes in pine stands were estimated using k-nearest-neighbour regression. The material consisted of 716 stands. Stands were located in the eastern Finland. Information regarding every stand was collected from the information system of one large Finnish timber-procurement organization. The accuracy of the k-nearest-neighbour method was compared with the traditional planning inventory method and stand inventory method. The created model was found to be a useful tool in the planning of wood procurement.

EN :

Wet bulk density and water content were determined with the standard soil-core method and by using a density and moisture gauge (gamma radiation and fast neutrons). Four soils collected at different forest sites were tested in the laboratory under different degrees of compression and at various water contents. Using the count ratios of the gauge for density and water as independent variables and wet bulk density and water content determined by soil cores as dependent variables, calibration equations were developed. For the soils used, the gauge values concerning wet bulk density were in close agreement with values determined with soil cores. However, the water content readings of the gauge had to be recalculated using the equations developed. The equations were tested on soil cores collected in the field after measurements with the gauge. The dry bulk density calculated as the wet bulk density given by the gauge minus the water content recalculated using the presented equations differed by an average of -1.6 percent from the soil-core values.

EN :

The spatial and heuristic road locating procedure developed in an earlier study [16] has been improved and integrated using microcomputers. Further applications and results of testing the procedure using the same data are presented. The improved procedure proved to be beneficial in helping forest road planning managers evaluate alternatives and hence select the optimal location for a road network. It contains a heuristic algorithm capable of locating forest roads so as to minimise the total costs and impacts of road construction, wood extraction, and wood transport.