Den skogliga informationens roll i ett kundanpassat virkesflöde

This MSc thesis is divided into two parts. The first part deals with the need for information from forest campartments selected for clear cutting, in connection with planning in an integrated forest- and sawmill enterprise. A review of literature is followed by a case stud y, where present conditions in a Swedish forest company are compared with current research in the area. The seeond part consists of a simulation stud y, which aims at camparing the accuracy of inventory estimates using different methods. The estimates are delivery forecasts, covering one month consumptian of timber in a large sawmill. The range of inventory designs includes systematic circular plot sampling as well as the use of register data in combination with a data base containing tree data. The results, i. e the forecasts and their standard errors, are presented separately for tree species, log type and diameter class. In many Swedish sawmill campanies of today, there is a trend in productian philosophies towards a greater adaption to customer demands. As a component in this process, the requirements on the flow of raw material will change. The right assortment, of the right quality, must be delivered at the exact right time. Due to the time span between harvest and delivery of timber from the forest, the mills will depend upon adequate forecasts. This implies controlied bucking to meet the demands from the mill, as well as improvment of existing models for predieting log yield from single forest stands. The stand data must allow flexible computerized bucking simulation, allowing adjustment to specific requirements at different points in time, generating prognoses for the distribution of logs into log classes after harves ting. Data used in the models can be collected through forest in ventory or by using stand register data. In the latter case, the diameter distribution must be constructed from the known stand charactaristics, by the use of mathematical models or by assignment from a data base with stem data. It might seem obvious that the information used in the models should be the best possible, but inventory actions are costly. The "total cost" of an inventory consists of two parts, one being the cost of performing the inventory and the other the expected loss, due to inoptimal decisions caused by erroneous data. The optimal solution is given by the minimization of the two components. Customer orientated production in a sawmill might entail great losses, due to lack of precision in prognoses regarding raw material, for products produced in close cooperation with important customers compared to standard products. Thus, different data acquisition policies should be used in stands containing different kinds of timber, to create prognoses adapted to the actual requirements in the industry. The integration between forest management and the sawmill industry, creating a customer oriented flow of raw material, is slowed down because of difficulties in expressing the demands on the raw material - the timber. In addition to this, the ability to forecast log yield is unsufficient, as well as the routines for follow-up between sawmills and forest departments. Large Swedish forest enterprices have the best prospects for overcoming these obstacles, due to large forest holdings as well as a modern sawmill industry. The use of information from forest stands harvested, for adapting the composition of the timber deliveries to the demands from the mills, will constitute a competitive edge for these companies. The development of systems such as computerized bucking control, information technology, including cordless communications, and positioning by satellite, creates the technical apportunities for tailoring the wood flow to customer requirements. Normally, when studying sampling methods for estimating log yield after clear cutting, the results are presented as total volumes of timber for pine and spruce. The results from the stud y indicate that the marginal benefit of sampling 25 sample plats, instead of 10, is small. The standard error of the estimate of total volumes is lowered by only l%, although the cost is more than doubled - from 40 000 SEK to 92 000 SEK, for a total volume of 50 000 m3fub. If no inventory action is performed, and instead register data connected to a data base containing tree data is used, the estimates are still useful. There is no variable cost using this method. The method for using register data outlined here is very straight forward and simple. By developing the constitution of the data base and the routines for assigning substitute data, it should be possible to improve the technique substantially. However, if the results are broken down on estimates of volumes distributed in to combinations of tree species, log type and diameter class, large variation becomes visible. This is most evident for butt logs with large diameter, where the standard error might amount to 50%, although the standard error for the total volume is only 3-4%. This implies that more intensive inventory designs should be used in compartments with large mean diameter. The term "adapted inventory design" is used to describe an inventory scheme in w hi ch different designs are used depending on the properties of the compartment More intensive designs are allocated to compartments with high values for mean diameter, mean height and stock. In other compartments more extensive inventory designs are used, e. g register data connected to a data base. Thus, the resources are allocated to compartments containing desired timber trees, and the estimates for selected segments are improved. The results indicate that it is possible to lower the standard errors for estimates of volumes in selected segments by using adapted inventory designs. This is done without increasing the over all inventory cost, compared to a common method in practice today.

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