Articles containing the keyword 'methods'

Cut-off importance sampling (CIS) is introduced as a means of sampling individual trees for the purpose of estimating bole volume. The novel feature of this variant of importance sampling is the establishment on the bole of a cut-off height, H_C, above which sampling is precluded. An estimator of bole volume between predetermined heights H_L and H_U > H_C is proposed, and its design-based bias and mean square error are derived. In an application of CIS as the second stage of a two-stage sample to estimate aggregate bole volume, the gain in precision realized from CIS more than offset its bias when compared to the precision of importance sampling when H_C = H_U.

• Robinson, E-mail: ar@mm.unknown
• Gregoire, E-mail: tg@mm.unknown
• Valentine, E-mail: hv@mm.unknown

The effect of species mixture was studied in a mixed stand of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) by simulating around 100 different treatment schedules during the rotation in a naturally regenerated even-aged stand located on a site of medium fertility in North Karelia, Finland. Both thinning from below and thinning from above were applied. Optimum rotations were determined by maximising the net present value calculated to infinity and different treatment schedules were compared with the net present value over one rotation as per rotation applied. In the optimum treatment programme, the proportion of pines was decreased by half of the basal area in the first thinning stage and by the end of the rotation to about one third. In thinning from above, the proportion of pines can be maintained at a slightly higher level. It is economically profitable to maintain the growing stock capital at approximately the level recommended by Forest Centre Tapio, a semi-governmental forestry authority. With non-optimum species composition, the loss in net present value over one rotation can be about 10 % in thinning from below and about 20 % in thinning from above.

• Vettenranta, E-mail: jv@mm.unknown

Fresh and herb-rich upland forest sites in the north-western part of the central boreal vegetation zone in Finland were studied with respect to vegetation structure and vegetation-environment relationships (soil, stand characteristics). Two fresh heath vegetation data sets, one from the northern boreal zone and the other from the central boreal zone, were compared with the data of this study using multivariate methods.

The variation in heath forest vegetation within the climatically uniform area was mainly determined by the fertility of the soil (primarily Ca and Mg) and the stage of stand development. N, P and K content of the humus layer varied little between the vegetation classes. Fertile site types occurred, in general, on coarse-textured soils than infertile site types, may be due to the fact that the sample plots were located in various bedrock and glacial till areas, i.e. to sampling effects.

The place of the vegetational units of the study area in the Finnish forest site type system is discussed. The vegetation of the area has features in common with the northern boreal zone as well as the southern part of the central boreal vegetation zone. The results lend some support to the occurrence of a northern Myrtillus type or at least that intermediate form of fresh and herb-rich mineral soil sites commonly occur in the studied area. It is argued that the older name Dryopteris-Myrtillus type is more suitable than Geranium-Oxalis-Myrtillus type for herb-rich heath sites in the study area.

• Lehtelä, E-mail: ml@mm.unknown
• Hotanen, E-mail: jh@mm.unknown
• Sepponen, E-mail: ps@mm.unknown

Much of forestry data is characterized by a longitudinal or repeated measures structure where multiple observations taken on some units of interest are correlated. Such dependencies are often ignored in favour of an apparently simpler analysis at the cost of invalid inferences. The last decade has brought to light many new statistical techniques that enable one to successfully deal with dependent observations. Although apparently distinct at first, the theory of Estimating Functions provides a natural extension of classical estimation that encompasses many of these new approaches. This contribution introduces Estimating Function Theory as a principle with potential for unification and presents examples covering a variety of modelling issues to demonstrate its applicability.

• Schabenberger, E-mail: os@mm.unknown
• Gregoire, E-mail: tg@mm.unknown

A simulation approach was applied to study the pattern of environmental variability and the relative statistical efficiency of 14 different plot types. The study material consisted of two nine-year-old field tests of Scots pine (Pinus sylvestris L.). The area of the test sites was 1.57 and 0.67 hectares. The efficiency was measured as the error variance attached to the estimate of family mean and the total size of a test needed to detect a given, least significant difference between two family means. The statistical efficiency tended to decline along with increasing plot size. The importance of plot shape was negligible compared to plot size. The highest efficiency was obtained with single-tree plots. Non-contiguous plots appeared to be considerably more efficient than block plots of equal size. The effects of intergenotypic competition on the choice of plot type are discussed.

The PDF includes an abstract in Finnish

• Haapanen, E-mail: mh@mm.unknown

An alternative approach to formulating a forestry goal programming problem is presented. First, single objective optima levels are solved. The Analytical Hierarchy Process is applied in the estimation of a priori weights of deviations from the goal target levels. The ratios of the weights can be interpreted as relative importance of the goals, respectively. The sum of the weighted deviations from all single optima levels associated with the management goals is minimized. Instead of absolute deviations, relative ones are used. A case study problem of forest management planning with several objectives, measured in different units, is analysed.

The PDF includes an abstract in Finnish.

• Kangas, E-mail: jk@mm.unknown
• Pukkala, E-mail: tp@mm.unknown

A measurement system developed for the parallel and real-time measurement of temperature, matric potential and oxygen diffusion rate (ODR) of a growth medium was assessed. The system consisted of a portable computer, a datalogger, temperature sensors, tensiometers and an ODR-meter with Pt-sensors.

For the measurements, proper sensor contact with the growth medium was needed. For matric potential measurement, appropriate shape and material of the tensiometer tips should be selected for different measurement purposes. The determination of oxygen diffusion rate is based on single, non-continuous measurements. The ODR-measurement required special care with the insertion and handling of the electrodes and selection of applied voltage. The ODR-measurement of a coarse peat medium was applicable only at matric potentials > -5 kPa. This measurement system was shown to be useful and suitable for accurate determination of thermal-, water- and aeration conditions of a growth medium under greenhouse conditions.

The PDF includes an abstract in Finnish.

• Heiskanen, E-mail: jh@mm.unknown
• Laitinen, E-mail: jl@mm.unknown

A third generation of forest tree gas exchange measuring system design for the use in the field is described. The system is designed to produce data for determining the dependence of the rate of tree photosynthesis, respiration and transpiration on environmental factors. The system consists of eight cuvettes, a tubing system, two infrared gas analysers, an air flow controller, a data logger, and a computer. The measuring cuvette is a clap type, i.e. it is mostly open, only closing during measurement. CO₂ exchange is measured as the change in the cuvette concentration of CO₂, and, transpiration is measured as the increase in water vapour concentration while the cuvette is closed. The environmental factors measured are temperature, irradiance and air pressure. The system was planned in 1987 and constructed in 1988. It worked reliably in late summer 1988 and the quality of data seems to be satisfactory. 

The PDF includes an abstract in Finnish.

• Hari, E-mail: ph@mm.unknown
• Korpilahti, E-mail: eeva.korpilahti@luke.fi
• Pohja, E-mail: tp@mm.unknown
• Räsänen, E-mail: pr@mm.unknown

The results of an intercalibration of sulphur analysis by 24 laboratories are evaluated. The analysis was made by one or more of six methods. The following three methods were found to be satisfactory as regards relative speed and reliability: Leco S analysis, X-ray fluorescence, and vacuum ICO emission spectroscopy.

The PDF includes an abstract in English.

• Jarva, E-mail: mj@mm.unknown
• Tervahauta, E-mail: at@mm.unknown

A light seismic method, a short-pulse radar and a microwave probe are tested in assessing the properties of a forest road constructed on peatland. The light seismic method gave reliable values for estimating the bearing capacity of the road. It was found that bearing capacity was mostly dependent on embankment thickness, but quality of fabric might also have an influence. Embankment thickness and peat depth can be measured on the radiogram, and some additional information on road bed and peat obtained. The microwave peat probe permits recording of the continuous moisture profile in situ, which improves accuracy of planning.

The PDF includes a summary in Finnish.

• Saarilahti, E-mail: ms@mm.unknown

Different sampling methods (the percentage cover scale, the graphical method, two-point quadrat methods, the five-, nine- and twelve-class cover scales, and the biomass harvesting) were used in estimating abundance of ground vegetation in clear-cut areas and on an abandoned field in Southern and Central Finland. The results are examined with the help of DCA ordinations. In addition, the species numbers and diversity indices obtained by different sampling methods are compared.

There were no large differences in DCA configurations between the sampling methods. According to all the sampling methods, a complex soil fertility-moisture gradient (a forest site type) was interpreted as the main ordination gradient in the vegetation data for clear-cut areas. However, different sampling methods did not give similar estimates of species numbers and diversity indices.

The PDF includes a summary in Finnish.

• Jukola-Sulonen, E-mail: ej@mm.unknown
• Salemaa, E-mail: ms@mm.unknown

The study deals with the interaction of various soil preparation and reforestation methods. The most favourable time of the year for broadcast sowing and the effect of stabilization after soil preparation on restocking were studied as special problems.

Prescribed burning, scalping and disc ploughing made a better combination with sowing than planting, and ploughing better combination with planting than sowing. The longer the period was between sowing and germination the fewer seedlings emerged. The best stocking was clearly resulted with sowing in June. Stabilization of soil after preparation had a negative effect on reforestation results.

The PDF includes a summary in English.

• Pohtila, E-mail: ep@mm.unknown
• Pohjola, E-mail: tp@mm.unknown

At a joint meeting of the Finnish Statistical Society and the Society of Forestry in Finland on 17.10.1984, papers were presented on the history and mathematical foundations of statistical methods used in forest inventory in Finland. The advantages and applicability of Bayresian methods and methods of spatial statistics were also discussed. In two papers, forest inventories were examined as part of a forest information system and the information demands of the user were discussed.

This article includes eight presentation held in the meeting. The papers have each a summary in English.

• Suomen tilastoseura, E-mail: –
• Finnish Society of Forest Science, E-mail: –

Berry yield of rowan tree (Sorbus aucuparia L.) was studied by picking and weighing the berries in a tree, counting the number of clusters by the eye, estimating the number of clusters by samples of 0.5 m², and by counting the dropped berries. In the last tree methods average weight of berries in a cluster was assessed by weighing a sample of clusters. The size of the tree and the abundance of the berries influenced the choice of method. The first two methods suited for small trees, the third for a tall tree with berries in abundance, and the fourth for those cases where birds had eaten a large portion of the berries.

The berry yields of 88 rowan trees were studied in Central Finland in 1983, a year of exceptionally high berry yield. The yield of berries averaged 23 kg per tree, the number of clusters 1,249 per tree and the number of berries 42,500 per tree.

The PDF includes a summary in English.

• Raatikainen, E-mail: mr@mm.unknown
• Rossi, E-mail: er@mm.unknown
• Vänninen, E-mail: iv@mm.unknown

Good correlation between radar reflection depth when using a FM-CW radar during winter and bearing capacity measurements during spring breakup was found. Therefore, it might be possible to evaluate the bearing capacity of forest roads using the radar sounding technique.

The PDF includes a summary in Finnish.

• Saarilahti, E-mail: ms@mm.unknown

A method to determine sulphur as sulphate has been applied to search for surface concentration of sulphate sulphur on needle samples. The method is based on reducing sulphates as volatile hydrogen sulphide gas by using hydriodic acid. The hydrogen sulphide gas is swept with nitrogen into an absorbent solution. Sulphide ion concentration in solution is then measured using ion selective electrodes.

The method was applied on one to four years old needle samples collected from Scots pine (Pinus sylvestris L.) at 0.9 to 15.9 km distances from a 1,064 MW coal-fired power plant in Southern Finland. Surface sulphate values found in the samples closer than 4 km to the power plant were 50 to 100% higher than a nearly constant background level. No significant variation of values with needle age was found. The advantages of the method compares to other methods for sulphur determination are speed, reasonable sensitivity and low detection limit.

• Hautojärvi, E-mail: ah@mm.unknown
• Ahonen, E-mail: sa@mm.unknown
• Erkinjuntti, E-mail: re@mm.unknown
• Katainen, E-mail: hk@mm.unknown
• Lappalainen, E-mail: tl@mm.unknown
• Raunemaa, E-mail: tr@mm.unknown

A semi-statistical model is suggested for monitoring injuries of plants for long-time field exposures (months). The model is based on the following assumptions:

1. The concentrations of air pollutants in the atmosphere follow the Johnson SB distribution.

2. The degree of plant injury is proportional to the logarithm of air pollutant dose.

3. No injuries occur below a certain dose level.

4. A dose is defined as the air pollutant concentration multiplied by the duration of exposure raised to an exponent.

Based on the air pollutant frequency distribution a total dose for the exposure period is calculated by integration, and the total dose is related to the observed plant injury by non-linear regression. The model is tested for long-time exposures of sulphur dioxide to transplant lichen in natural environment.

• Moseholm, E-mail: lm@mm.unknown

A technique for instrumental scoring of damaged leaves on tobacco (Nicotiana tabacum) indicator plants caused by ozone in the lower atmosphere is being developed. The leaves are photographed in situ with an integrated unit, which illuminates the leaf from behind and keeps the camera in a well-defined position. By using microfilm and a minus green filter, it is possible to obtain negatives where the necrotic flecks appear as dark spots on a white leaf. The negatives are scanned in a TV-system and the size of the damaged fraction of the leaf is calculated by a microprosessor and is shown as a percentage of the leaf.

• Mortensen, E-mail: lm@mm.unknown
• Weisberg, E-mail: kw@mm.unknown

The water in different parts of a plant forms a continuum throughout the plant body. This makes it possible to record changes in the water content as changes in thickness of any part of the plant. A leaf kept in darkness has been found to change its thickness to a sufficient degree for recordings of changes in transpiration from the rest of the plant. The rapidness of the changes makes it probable that they are mirroring the stomatal movements.

The method has been used for recording of influences of SO₂ as air pollutant. It has a couple of advantages over direct measurements of changes in transpiration. One is that the measurement can be used without enclosing the plant in a cuvette. Another is that possibly occurring effects on the hygrometer are eliminated. The method has until now mainly been used for wheat plants but also woody plants as Pinus and Salix have been tested.

• Rufelt, E-mail: hr@mm.unknown
• Wiese, E-mail: bw@mm.unknown

The use and problems of the sucrose inversion method for the study of forest humus and soil are discussed. The method is based on the temperature dependence of sucrose inversion, changes in rotation angle being determined with a circle polarimeter. Average temperatures and thermal sums for forest humus in different forests in Finland were measured, using this method, for a period of ca. 100 days. The results are not considered definitive but are regarded rather as examples. Average temperatures were somewhat higher in the humus of dry and poor heath forests than in that of moist and herb-rich forests, with exceptions that could be explicable by topographic position.

The PDF includes a summary in English.

• Ohenoja, E-mail: eo@mm.unknown
• Pohjola, E-mail: lp@mm.unknown

This paper presents the principles of a unified data processing system suitable for derivation of the most variables of interest in forest mensuration. The precedence (succedence) relations between the tree and forest stand variables are analysed and a block-wise simultaneous recursive multi-equation model is suggested to describe these relations. Regression analysis is used in the estimation of the model parameters and Taylor’s series and Monte Carlo simulation are available in the derivation of the unbiased results.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown

The general requirements for forest information required in forest management include the availability of quantitative data concerning forest areas and timber volume, data describing that structure and quality of the forest by classes, data dealing with the forest dynamics such as increment and mortality, stand-wise data tied to on-the-ground locations, and the timelines of all this information.

A review of the present inventory systems reveals variations in the information used to manage forests. In many cases, there appears to be an inadequacy of information. There may be no inventory system, or sampling may concern only overall features of the forest. The general trend has been towards a more common use of delineation of stands and the estimation of stands characteristics. In European countries, survey techniques have been improved by, for instance, trying to avoid subjective features in stand-wise assessments and through the use of index sub-compartments which are remeasure. In North America, a new approach was recently introduced to generate stand tables which seems to have significant inventory capabilities. In some cases, the advanced inventory systems may simultaneously employ three kinds of inventories.

In designing an inventory and management information system experiences gained elsewhere should be utilized with studies of sampling methods, remote sensing techniques, new instrumentation and computer services. Improved decision making makes it possible to introduce cheaper methods for periodic inventories. The information system should be only as elaborate as is required to do the job. The costs of acquisition of inventory information correlates with a degree of sophistication of the system, but rarely exceeds one percent of the stumpage of the timber cut. Also, the increase in wood production more than compensates the costs of planning on the basis of inventories.

The PDF includes a summary in Finnish.

• Nyyssönen, E-mail: an@mm.unknown

Ashed tree samples from sound and decayed Norway spruce (Picea abies (L.) H. Karst.) were studied by means of fast neutron activation analysis, and for comparison, also by X-ray fluorescence analysis. In fast neutron activation analysis, the following elements were detected: (Na), Mg, Al, Si, K, Ca, Mn, Rb, Sr and Ba, and according to the results of the X-ray fluorescence method the elements present in the wood samples were: K, Ca, Mn, Rb, Sr and Ba. A general diminishing was revealed by both methods in most elemental concentrations studied, with exception of K and Rb, when going from a sound tree to a decayed one. The use of the ratio of the amounts of potassium to calcium as an indication of the degree of decay is therefore proposed.

The PDF includes a summary in Finnish.

• Raunemaa, E-mail: tr@mm.unknown
• Hautojärvi, E-mail: ah@mm.unknown
• Jartti, E-mail: pj@mm.unknown
• Laurén, E-mail: jl@mm.unknown
• Lindfors, E-mail: vl@mm.unknown
• Räisänen, E-mail: jr@mm.unknown

The investigation is concerned with testing chemical totalizer of radiation (Frankfurt radiometer) for use in measuring the components of a simple energy balance (latent heat = net radiation – sensible heat) so as to gain an estimate for evaporation. The meter is based on the temperature dependence of the inversion rate of sugar solution. The relationship is exponential. It was found that radiation sums for 2–6-day periods can be reliably determined with this meter when global radiation is below 20 MJ·m^-2d^-1. Determining sensible heat is noticeably inaccurate, and hence the calculation of evaporation values, too. In comparing evaporation from different types of ground and plant cover one thus has to be content with drawing conclusions on the basis of net radiation values. The totalizer is therefore only suited to describing radiation conditions.

The PDF includes a summary in Finnish.

• Mannerkoski, E-mail: hm@mm.unknown

The physical methods currently available for measuring the internal decay of living trees is examined in this study. Although this is mainly a review, it can be concluded that some measurements shed more light on the problem. Examination of ultrasonic methods reveals that the coupling of ultrasonic energy from the transducer to the tree is not efficient. Both impulse and ultrasonic testing work best with decayed and hollow trees. The electrical resistance measurements of stumps gave resistance values for sound wood 300–400 kΩ, for decayed and discoloured wood about 12 kΩ and for cambium about 12 kΩ. The neutron activation gives good results, and in particular it reveals nicely the increasing concentration of potassium in decayed wood. The internal decay of living trees was not examined.

The PDF includes a summary in Finnish.

• Jartti, E-mail: pj@mm.unknown

The aim of the study was to find out the technical and economical applicability of seismic survey methods of sub-surface earth investigations in forest road planning. Two seismographs, SOIL-TEST MD 1 and BISON 1570, were tested in studyin 31 cuts and 3 gravel areas. The devices proved to be usable in field conditions. Sounding one spot costs about 75 Fmk and methods’ rentability is greatly based on the ration between expected and unexpected events, which depends on the areal geology. It is profitable to purchase the device especially if digging out of unexpected bedrock causes high costs.

The PDF includes a summary in English.

• Saarilahti, E-mail: ms@mm.unknown

In this study two methods of determining the basic density of total tree chips are compared. The method of Mäkelä (1977) is based on the volumes of Scots pine, Norway spruce, birch, and alder in a logging area, and the age of the trees. In the other method the basic density of total tree chips is measured by the common displacement method. The correlation was 0,730 in the material of 22 logging areas. Besides this it was found that the basic density of chips increases as the size of the chip particles increases with the exception of the smallest particles.

The PDF includes a summary in English.

• Kärkkäinen, E-mail: mk@mm.unknown

A quantitative method for determining the annual growth level of plant species has been presented. In particular, attention was paid to the dependence of the growth level on the amount of light available for photosynthesis. A mathematical model for the dependence of structural matter production on photosynthetic production has been presented for some plant species.

The study is based on the assumption that the total amount of annual net photosynthesis plays a role of primary importance in determining the relationship between photosynthetic production and structural matter production. The basic environmental factors determining the photosynthetic rate are light and temperature, if the water and nutrient supply is adequate. The dependence of photosynthetic rate on light and temperature was determined by monitoring the CO₂ uptake rate of natural plant populations between the photosynthetic levels of different plant populations with an infrared gas analyser.

The PDF includes a summary in Finnish.

• Väisänen, E-mail: ev@mm.unknown
• Hari, E-mail: ph@mm.unknown
• Kellomäki, E-mail: sk@mm.unknown

The paper describes a method for the measurement of basic density of total tree chips. In the method the chips are placed in a container, which is immersed in a cylinder full of water, and the container is weighted at two levels. In the upper part of the cylinder the pressure against the air bubbles is smaller than in the lower level. In this method, the effect of air bubbles in the result can be eliminated. Besides this, due to homogenization of the material to be measured only small number of samples are needed for the estimation of the average basic density.

The PDF includes a summary in English.

• Kärkkäinen, E-mail: mk@mm.unknown

Light intensity inside the canopy varies considerably both in space and time. A new apparatus was developed which is disturbed as little as possible by the above-mentioned variation. The construction is based on the linear relationships between light intensity (measured using silicon diodes) and photosynthesis. This procedure permits linear operations (summing and integration) to be carried out on the output of the diodes without any loss of accuracy. There are five diodes in each assimilation chamber. A model, in which the independent variables include ligth, measured with the present equipment, and temperature, fits the photosynthetic rates well even inside the canopy.

The PDF includes a summary in Finnish.

• Hari, E-mail: ph@mm.unknown
• Huhtamaa, E-mail: mh@mm.unknown
• Pelkonen, E-mail: pp@mm.unknown
• Pohjonen, E-mail: vp@mm.unknown
• Salminen, E-mail: rs@mm.unknown

The planning of timber production in a forestry unit is divisible into two phases. In the first phase, planning provides the decision-maker with a number of possible timber production policies; these policies define the production possibility boundary. After the decision-maker has chosen one of these policies, planning moves to the second phase, in which a detailed programme is prepared with a view to meeting the requirements of the timber production policy accepted. The paper indicates one possibility of solving these two tasks simultaneously. In the first phase, the solution of the primal linear programming problem is employed and in the second phase the respective dual or shadow price solution.

The PDF includes a summary in English.

• Kilkki, E-mail: pk@mm.unknown
• Pökälä, E-mail: rp@mm.unknown
• Siitonen, E-mail: ms@mm.unknown

An electron probe X-ray microanalyser was used to study the occurrence of phosphorus, sulphur and calcium in the bud apices of dormant Scots pine (Pinus sylvestris L.). The material was collected during the winter months (November–February), fixed in Carnoy’s fluid, dehydrated, and mounted in paraffin wax. Of the 10 μm longitudinal section, the ones containing the middle portion of the apices were glued to the specimen supports and vacuum coated with aluminium. Three parallel line analysis were run over the corpus and the uppermost portion of the pith. Results obtained so far suggest that no marked changes occur in the position and level of the three elements during the study period.

The PDF includes a summary in English.

• Kupila-Ahvenniemi, E-mail: sk@mm.unknown
• Hankonen, E-mail: sh@mm.unknown
• Sivonen, E-mail: ss@mm.unknown

In this literature review some error possibilities in the measurement of solid volume of logs and pulpwood are discussed. Although both underestimation and overestimation can occur for various reasons it seems likely that in the stereometric measurement method the real volume is underestimated, at least when Huber’s formula is applied, and the respective middle form factors are too low. Numerous results of empirical investigations are presented in the paper, too.

The PDF includes a summary in English.

• Kärkkäinen, E-mail: mk@mm.unknown

The study describes the relationships between a method developed by the author for the calculation of the profitability of forest drainage and the old biological method. The calculations were based on empirical data, and they aimed at finding out the effect of a variation in the profitability limit in the areas in hectares to be drained, and on the profitability of drainage. The study deals also with the profitability of present-day drainage activities. The results showed that the profitability coefficient (the ratio between the discounted increase in returns and the costs of drainage) averages 3.04 for the whole country. The corresponding value was 5.68 for Southern Finland, 3.19 for Central Finland and 1.67 for Northern Finland.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

Among the users of factor analysis there seems to be a tendency to extend the use of this method to tasks where it suits poorly. It is therefore important to emphasise at least the following aspects: 1) More critical attention should be paid to problems of interpretation especially at situations where method is aimed at analysing the causal relationships among the variables; 2) The study problem should be stated so clearly as to make it plausible to evaluate the suitability of factor model to the problem.

The PDF includes a summary in English.

• Järveläinen, E-mail: vj@mm.unknown

A hypothetic problem is outlined as an example of the type of problem to which factor analysis should not be applied. Apart from this, attention is paid to industrialisation, a concept characterised by several variables, none of which can be held constant while analysing its influence on attitudes by multi-variable cross-tabulation techniques.

The PDF includes a summary in English.

• Riihinen, E-mail: pr@mm.unknown

Some alternative ways of using factor analysis in the field of forest owners’ behaviour are explored in the article, in the light of two new Finnish publications. The philosophical and mathematical propertied of factor analysis are often considered too restrictive, and thus its applicability to different fields too limited. A good knowledge of the method and the subject matter theories seems to be an important prerequisite for a successful application of factor analysis. Otherwise the researcher is too dependent on the general recommendations concerning the use of factor analysis and cannot fit its use in his special situation and the whole methodological setting of the study.

The PDF includes a summary in English.

• Hahtola, E-mail: kh@mm.unknown

The aim of the study was to investigate the effect of four packing methods on the field survival and growth of seedlings and transplants of Scots pine (Pinus sylvestris L.) stored over the winter in a cold-storage cellar. The following sorts of plants were used: one-year-old seedlings (1+0) grown in a plastic greenhouse, two-year-old (2+0) open grown seedlings and three-year-old open grown transplants. These plants were stored in open wooden boxes, in sealed plastic bags, in boxes with wet peat on the bottom and in plastic-laminated paper bags.

The control plants were of the same types and were kept in a nursery over the winter. The storage was carried out in a mantle-chilled cold-storage from October 1966 to May 1967. The temperature in the cold-storage was kept around -2 °C and the relative humidity of the air over 90%. The water content of a randomly selected sample plants showed no increase in water deficit after the storing. Part of the seedlings were transplanted in the nursery and the rest were planted in a clear-cut area. A number of the latter plants were treated with an insecticide (1% Intaktol, which contains DDT, Lindane and dieldrin) before planting. All the experiments were examined after one growing season and the planting experiments the next fall.

The transplants (2+1) in the nursery, and in the forest had survived and grown better than the seedlings. In the nursery the 1+0 seedlings survived and grew better than the 2+0 seedlings. There was no difference in mortality between the seedlings. After the first growing season occasional significant differences between the packing methods were observed, but they disappeared during the second growing season. Thus, all packing methods proved to be as successful as the control method without winter storage.

Transplants were more often attacked by the large pine weevil (Hylobius abietis L.) than the smaller seedlings. The damage, however, was considerably greater on the seedlings because of their lower resistance. No significant differences in the Hylobius-attack between the packing methods could be observed. The Intaktol-treated plants were as often attacked as the untreated ones, but the damage was slighter on the treated ones.

The PDF includes a summary in English.

• Långström, E-mail: bl@mm.unknown

The article is a lectio praecursoria held on May 18, 1968 at the University of Helsinki. It deals with some aspects connected with the adaptation of mathematic-statistical methods and in particular with multivariate methods. Among these regression, factor, and principal-component analysis are mostly used by the Finnish forest economists.

The PDF includes a summary in English.

• Mäkelä, E-mail: jm@mm.unknown

18 permanent sample subplots of the Swedish and the Hassian Forestry Institute, each measured in equal intervals for several decades, were divided into subplots of different size. An analysis of variance was calculated for every set of subplot size. The development of intraclass-correlations over years and over different sizes of subplots could be explained if three different correlations were assumed: soil-correlation, correlations from irregular distribution of the trees, and correlation resulting from competition. Intraclass-correlations were positive or negative depending on dominance of one or two of these correlations.

An explanatory simultation study of competitional variance showed the effect of the degree of competitional correlations on the variance of means of subplots of different sizes. If this coefficient was small, all variances of subplots means within the range investigated became larger than expected in experiments without competition, with larger coefficients the variances of means of the smaller subplots became smaller, those of larger subplots larger than expected.

Plots of medium or large size are probably optimal for long term experiments with forest trees, if all sources of costs in such experiments are taken into account.

The PDF includes a summary in English and Finnish.

• Stern, E-mail: ks@mm.unknown

The present study gives an account of the dependence prevailing between the actual volume of timber crops, and, on one hand, the sum of cylindrical volume of individual trees, and on the other hand, the utilization per cent. This dependence is rectlinear if the volumes in question are calculated on a running-foot basis. The cylindrical volume of individual trees was calculated on the basis of cross-section area at breast height and the height of the trees. On the basis of the results, it seems that it is possible to simplify timber measurement.

The PDF includes a summary in English.

• Nisula, E-mail: pn@mm.unknown

The present study is an attempt to clarify the decrease in growth, or the increment loss, caused by sudden reduction of growth of the growing stock below a certain level, and to find a method for its determination. Increment loss is defined as a decrease in growth during the rotation due to a deficient stock volume. The material consists of Koivisto’s yield tables for repeatedly thinned stands in Southern Finland, and the results of the Third National Forest Inventory concerning the mean volume and increment in the productive sites.

For the calculation of increment loss three formulae were constructed where the increment loss is calculated 1) as the difference between the removal by thinnings in normally developed stands during a time equal with the period of deficient stock and the suddenly removed stock, 2) according to the compound interest calculation principle as the sum of the differences which are obtained by subtracting from the removal in each thinning during the period of deficient stock its initial value, and 3) as the straight interest of the stock deficiency during the period of deficient stock.

According to the calculations, the increment loss is greatest in stands to be grown, viz. 50 m³ solid measure excluding bark per hectare tended Norway spruce stands on Oxalis-Myrtillus type sites at 40% deficiency below minimum stock. In stands to be regenerated the losses are, too, greatest in the similar stands. It exceeds 200 m³/ha when stands younger than 50 years have to been regenerated and the removal amounts to 50% of the stock. In stands to be regenerated the increment loss for spruce, due to the slow initial development by the species, is greater than for Scots pine and birch. The loss is the same at different period of age if the relative deficiency of the stock is of equal size.

According to the study, each stand has a characteristic variation in the increment loss which depends mainly on the relative degree of deficiency from the minimum stock. The formulae and methods can be used to determine the increment loss in average and better stands in Southern Finland when the stock suddenly decreases.

The PDF includes a summary in English.

• Matilainen, E-mail: tm@mm.unknown

One forest drainage undertaking in Finland often consists of woodlots belonging to several owners, and over hundred owners may be involved. In the present paper a method for allocation the costs to different owners in a joint drainage undertaking is worked out. The problem has been emphasised by the new Waterways Law, which enables also such drainage projects to be undertaken to which some of the land owners oppose. In those cased the costs must be allocated according to the benefit driven by each owner from the project.

The method attempts to assess the benefits to be driven from the forest drainage, those costs of the drainage that are joint and thus subjected to allocation, and what is the area affected by drainage as used as a basis for cost allocation.

The joined costs are apportioned in the following manner. The area of peatland adjusted to differences in the benefit obtained by drainage is ascertained by the land holder by multiplying the index number by the corresponding areas. In the case of cultivated agricultural land, also an index showing the need for drainage is used in computing the adjusted area. Each topographic unit in the map is provided with a notation of its apportionment area. Joined costs are allocated to different land owners in relation to their adjusted land areas.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Keltikangas, E-mail: mk@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

The aim of this study was to find out to what extent it is possible to time phases of work by making instant observations at regular intervals according to the principles of the method of random samples, and arrive at similar results as obtained by timing continuously with a decimal-minute stop watch. In the first mentioned method the observer of the time study is given a sound signal at even intervals, in this case each 1/10-minute period, during the signal he records the phase of work (element) the object is performing.

The material of the study consists of studies in skidding and loading in connection with transportation by tractor during a period of 8 days. The duration of each element in using tractor hand in skidding and hauling was measured with an ordinary stop watch using repetitive timing. This material was then converted into random sample material.

The analysis of the material showed that the method of random samples yielded observations from all phases of work present in the material obtained by measuring with the stop watch. The duration of elements as determined by the random-sample method were of the same order as determined with stop watch. The results did not cause any observable systematic deviation or rhythmic repetition of elements.

The PDF includes a summary in English.

• Nisula, E-mail: pn@mm.unknown

In connection to the Third National Forest Inventory of Finland, two survey strips in the northernmost Finland were photographed on scale 1:15,000. Infrared films and a yellow filter were used. For the present experiment a total length of 66 km of the strips was photographed. The strips were surveyed visually from the ground by stands. Sample plots were measured at kilometre intervals. The aerial photographs were surveyed the distances covered in the ground. The work was aided by stereograms which showed 16 large-size sample plots localised on aerial photographs.

The main groups of land identified along the survey line were productive and poorly productive forest land, wasteland and another land, in addition, peatland and firm land were distinguished. Although some differences were noted, the two survey methods provided fairly similar results. For an estimation of the tree species composition the material is one-sided since the district is mainly Scots pine. The principal tree species was successfully distinguished on aerial photographs in 78 out of 82 comparable pairs.

The mean of ground observations of dominant height of the stands was 10.9 m, that of observations on aerial photographs 11.2 m. The result of stand volume estimates reveals a distinct correlation between the various methods of estimation.

In an earlier study it was shown that it is possible, using a stand volume table based on characteristics revealed in aerial photography, to create a general idea of stand volume on the southern half of the country. A few additional factors, of interest for the stratification necessary in forest inventories, were also studied. A distinct correlation was observed between the results of aerial and ground survey for all the characteristics discussed. The present experiment showed that the prerequisites for stratification through aerial photographs do exist. Further investigation is needed into the most appropriate methods for stratification in each situation.

The PDF includes a summary in English.

• Nyyssönen, E-mail: an@mm.unknown
• Poso, E-mail: sp@mm.unknown

A picture of growth rings of a tree can be obtained on paper by placing it over a disc of a trunk or stump and rubbing it with a pencil. The ‘shadows’, while not yielding the complex data obtainable from the actual wood, do show the proportion of the growth rings composed of spring wood and the denser summer wood. It is possible to collect large amount of data by using an unexperienced staff cheaply and quickly, and the samples may be mailed at little expense. The method may be used to study the previous cuttings of a stand from stumps. The shadowing of tree rings is possible to do even from rather decayed stumps.

The article includes a Finnish abstract.

• Rogers, E-mail: mr@mm.unknown

Silva Fennica Issue 80 includes presentations held in 1952 in the 7th 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.

This presentation describes history of wood harvesting and logging methods used in the state forests in Finland. The article discusses  the problems caused by, for instance, of light sellection fellings to the silvicultural state of the forests. The silvicultural state of the forest could be improved by introducing silvicultural logging methods, and selection of seed trees to improve the genetic quality of seeds used in regeneration.

• 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 use and purpose of statistics about different felling methods compiled in Forest Service.

• Aro, E-mail: pa@mm.unknown

The article gives a review on the history of forest management in the Northern countries. The article concludes that in the Northern Countries with their immense supplies of forest and small demand, because of sparse population, there was no hurry for developing the study of forest economics, as was the case in Central Europe. It was only when the modern wood using industry had revolutionized the marketing conditions, that the opportunity was provided for forest economics to develop. The paper introduces the book ’Om skogarnas skötsel in Norden’ (Silviculture in the Northern Countries) written by a Finn C.C. Böcker. That paper was compiled in behalf of a request of the king of Sweden, King Carl XIV Johan, who offered a price to a person who would draw a scheme for organizing forestry in Sweden, where Finland at that time belonged to. The prize was divided by Böcker and a swede, af Ström.

The PDF includes a summary in Finnish and English and the original text in Swedish.

• Böcker, E-mail: cb@mm.unknown

The aim of this investigation is to study, for north European conditions, some overall standards of accuracy attainable in the estimation in a number of forest characteristics from aerial photographs. Field data was acquired in three areas, comprising whole stands, fixed and variable size sample plots and sections of survey strips.  

The results show that land use classes could be estimated to a rather high degree of precision from aerial photographs. The accuracy of determination of the main tree species (Scots pine, Norway spruce and deciduous trees) was more moderate; three quarters of all stands were interpreted correctly from the present photographs. The estimate of pure stands was noticeable better than those for mixed stands. In general, the agreement between treatment class stratification in the field and from aerial photographs was poor, as only one-third of all cases the class was same. The dominant height was estimated with relative lack of bias for small stands, but systematic underestimation of nearly 2 m existed for high stands.  

The emphasis in this investigation was laid on determination of the volume of growing stock. Stand volumes in the small and medium volume classes were overestimated, against clear under-estimate for high volume stands. The standard error of difference, including bias, was ±43 both in m3 and as a percentage. 

The variance data available provide a basis for the conclusion that under some conditions photo stratification within the forest land seems to improve the efficiency of volume estimation, whereas in some other cases the stratification is hardly an economic proposition. Alternative computations made from the data of an experimental survey indicated the likelihood that no gain was deprived from the use of aerial photographs for volume class estimation. 

The PDF includes a summary in Finnish.

• Nyyssönen, E-mail: an@mm.unknown
• Poso, E-mail: sp@mm.unknown
• Keil, E-mail: ck@mm.unknown

This paper reports on tests made for the study of alternative methods in forest survey. Data were acquired by measurements in five areas in Finland and in Mexico, varying in size from 20 to 900 ha. The principal characteristics used in the analysis was the entire volume. By the combination of neighbouring plots, the variation could be studied for different plot sizes and survey strips. Variable (relascope) plots could be compared.

A starting point for the comparison of different sampling methods, calculations were made of the coefficients of variation for each plot type; total and within the strata. The amount of decrease of variation with an increasing plot size could be established. Comparisons have been made of the following sampling methods: simple random, stratified random, simple systematic, and stratified systematic sampling.

On comparisons of the standard error of sample mean it was found that in both stratified sampling and different types of systematic sampling there is, with increasing size and diminishing interval of sample plots, an increase in the relative improvement of the result against simple random sampling. Only in exceptional cases did systematic surveys give results which were less precise than those derived by other methods.

In discussion of some methods for determination of the precision of systematic sampling, possibilities of theoretical determination of the degree of precision was considered. An empirical study was made of the behaviour of some equations based on the sample itself. The larger the plot size and the shorter the plot interval, the more the equations overestimated in general the variance of sample mean.

As none of the equations studied gave reliable results, regression equations were calculated for the relative standard error on the basis of the data measured. The independent variables were plot size, plot or strip interval, area of survey unit and mean volume. The results arrived at are based mainly on the complete measurement of one area only. To enable extension of the scope of application, more material is needed with a complete enumeration of trees.

The PDF includes a summary in Finnish.

• Nyyssönen, E-mail: an@mm.unknown
• Kilkki, E-mail: pk@mm.unknown
• Mikkola, E-mail: em@mm.unknown

Highest degree of precision in determining the areas of different strata in forest survey is achieved when the areas are measured from a map. However, in practice the stratum-areas usually need to be determined on the basis of samples taken in the field or from aerial photographs. The goal of the present investigation was to determine the precision in stratum-area estimation on the application of different sampling methods.

Three sampling methods were used: 1. sampling with random plots, 2. uniform systematic plot sampling, and 3. sampling with equidistant lines.

The dependence of the standard error of stratum-areas in systematic line and plot sampling was examined by regression analysis. The models for regression equations were derived from random sampling formulae. It appears that the characteristics of these formulae were applicable as variables in the regression equations for systematic samples. Also, some characteristics of the distribution of the stratum was found, which seem to influence the error in sampling with equidistant lines.

The results as regards uniform systematic plot sampling indicate that the use of random sampling formulae leads to considerable over-estimation of the standard error. Nonetheless, unless relatively short intervals between sample plots are used in the forest survey made on the ground, it is of advantage to study the division of the area into strata by measuring the distribution of the survey lines in these strata.

The results can be used in two ways: for estimation of the precision in a survey already made, or to predetermine the sample size in a survey to be made. The results may be applicable to areas ranging from 100 to 1,000 ha in size, as well as to larger areas.

• Nyyssönen, E-mail: an@mm.unknown
• Kilkki, E-mail: pk@mm.unknown

The purpose of this paper is to review tests made on the basis of Finnish material with regard to the efficiency of the 10-point cluster in sampling a stand in forest inventory. Currently, this system is applied in field work in the national forest surveys in the United States of America. The paper reports on tests, made on the basis of Finnish material, for comparison of the 10-point cluster of variable plots with 13 other designs in sampling a stand in forest survey. The research material consists of 12 stands, with Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) as the main species.

The main results are concerned with the ability of different designs to provide gross volume estimates. As a measure of efficiency, three alternative series of variances were used, adjusted by three alternatives of time. The results are applicable, for instance, in double-sampling with photo and field classifications. In the comparisons, no attention was paid to the possibility of systematic errors in various designs.

For inventory volume, the 10-point cluster proved to be about 10 per cent less efficient than the best design of each alternative. The use of a single circular plot of 1,000 m² can be recommended under the conditions of this test; furthermore, one or two 500 m² plots were more efficient than any combination of variable plots.

The reason for the use of the 10-point cluster in forest surveying has been the ability of the design to provide simultaneous information on area condition classes. Among the designs tested, the 10-point cluster seems to be the only one capable of application in the estimation of condition classes.

Most of the information obtained by means of the 10-point cluster can be gained through ocular estimation, and from the sample trees to be measured in any design, but a cluster of several points appears to offer good means of estimation, for instance, of the presence of clumps and gasps in a stand.

• Nyyssönen, E-mail: an@mm.unknown
• Kilkki, E-mail: pk@mm.unknown

Quantitative investigation of bacteria in the humus is needed when the intensity of their function in decomposition in the soil is studied. In this study bacterial density of humus was measured using dilution plate method, which was subjected to thorough investigation. The method was chosen, despite its complexity, because it is quite consistent, each stage can be studied separately and the reliability can be tested. The aim of the study was to determine the best way to take samples so that the sample will represent the bacterial population as closely as possible, and to optimize homogenization and dilution of the sample and the assays.

On the basis of the results of the investigation, a procedure was developed for quantitative determination of aerobic bacteria in the humus by the dilution plate method. The paper recommends that subsamples are collected systematically from at least 25 different points. The moisture and temperature of the samples should remain similar to the natural environment until preparation of the dilution. The sample was homogenized with the Bühler homogenizer, which is constructed so that a certain degree of asepsis can be maintained and the speed of the apparatus can be regulated. The content of the mineral nutrients of the sample must be determined when choosing the way of homogenization to obtain the highest number of colonies per plate. The sample was diluted with either 0.1–0.01% peptone solution or 0.5% soil extract. The most advantageous degree of dilution was obtained by testing with the aid of Fisher’s dispersion index the probability of the Poisson distribution in the results.

• Schalin, E-mail: is@mm.unknown

The most important fact to consider in attempting to develop an increment forecast method is the great dependency of the increment on the growing stock volume. Although the site (soil and climate) produces the increment and volume, there would be no increment without the volume as an increment capital. The cutting possibilities are still more dependent on the existing growing stock. Thus, the primary characteristics in management planning is the growing stock volume. The methodological starting point in this paper is that the increment is considered dependent variable which can be explained by other growing stock characteristics. The basis of the analysis and the primary object of this investigation is the increment percentage. Using available and measured sample plots the increment percentage will be analysed as a dependent variable by other growing stock characteristics.

The main emphasis will be the methods which can be used in connection with the interacting increment and drain. An increment-drain forecast should give at least approximately the allowable cut in timber products. Thus, it will be attempted to find the stock characteristics determining the amounts of timber products.

The article introduces the theory and basic concepts of the increment-drain process, increment functions and basal area – height method, and discusses estimation of timber products in increment-drain forecast, fluctuations of the increment, mortality in connection with the increment-drain forecast, and the scheme of cutting budget for desirable growing stock. Finally, it gives some proposals, based on the investigation, for preparing an increment-drain forecast for a large forest area.

The PDF includes a summary in Finnish.

• Kuusela, E-mail: kk@mm.unknown

The present study deals with correlation between level of ground water table and water content of peat in peatlands drained for forestry. The results have been obtained partly from field studies and partly from experiments in the laboratory.

Both the field and laboratory experiments proved that a close rectilinear correlation exists between the level of the ground water table and the water content of surface peat. A given change in the level of the ground water table corresponds to a smaller change in the water content the deeper the peat layer examined is situated. The change in the water content in the surface layer (0–20 cm) in the cases studied was of such a magnitude that a change of 10 cm in the level of the ground water table corresponded to a change of about 5 volume per cent. In deeper layers the change was smaller. The state of equilibrium regulating the water content of the peat is relatively stable. It is possible that the so-called optimum drainage of a peatland for each tree species can be theoretically determined on the basis of the correlation between the water content of peat and the level of ground water table.

The method used in the study, the repeated weighing of peat samples in their original place, has proved to be very useful and decisively better than the method based on one-time samples. The experiment also indicate that the correlation can be determined with laboratory experiments.

• Heikurainen, E-mail: lh@mm.unknown
• Päivänen, E-mail: jp@mm.unknown
• Sarasto, E-mail: js@mm.unknown

A comparison was made between two alternative methods of continuous national forest inventory. In method 1, samples measured annually are taken throughout the country, in method 2 samples are confined to one section of the country each year. The figures are derived from national forest inventories carried out in the North-European countries Finland, Norway and Sweden. Systematic sampling on the ground has been employed without remeasured sample plots. Field work consisted of survey tracts.

For the whole country, method 1 gives results, which are continuously up-to-date, although detailed information requires observation over a period of several years. On an average, the results obtained from method 2 area at least n/2 years old (survey cycle n years). For a specific section of the country, method 1 gives preliminary results already in 1-2 years, but more accurate results are at least n/2 years old. Method 2 gives accurate results every n^th year. Thus, method 2 is not always to be recommended, even if the emphasis is laid on regional information and planning.

To gain knowledge of annual timber removals, often necessary in assessing the forest resource situation, stump measurements can be used, either exclusively or by way of control. The corresponding sampling must be affected throughout the whole country, and this can be done only when method 1 is used. Other information required annually, such as estimates of seed crops, occurrence of pests or annual variation of growth due to the climate, favour method 1.

It can be concluded that method 1 has important advantages, although these must be bought at higher costs. A comparison of inventory costs shows, assuming the same degree of accuracy, that the total expenditure for method 2 is 7-8% lower than that for method 1, owing to the difference in transport requirements. Also, other aspects may affect the choice of method, for example, the use of aerial photographs may be arranged more efficiently in method 2.

• Nyyssönen, E-mail: an@mm.unknown

Lowering of the ground water table is caused by decrease in the amount of water because of evapotranspiration. Evapotranspiration of a forest is determined by converting a lowering of the ground water table into a decrease in the amount of water. This paper describes a method to determine the transpiration of tree stands and ground vegetation as well as total evaporation on a Finnish drained peatland, which ground water table was relatively high, by measuring the level of the ground water table.

It was shown that in drained peatlands with relatively high ground water level, the ground water table fell during the day between about 9 a.m. and 6 p.m., and remain at approximately same level during rest of the day. The fall of ground water table was caused by transpiration of the trees and ground vegetation, and could be over 20 mm. Thus, measuring the daily lowering of ground water table can be used to estimate transpiration of the trees. When the method is applied to measuring the total evaporation of longer periods of time, also rainfall, interception, stand rainfall and stemflow have to be measured. The method is applicable only on sites with relatively high ground water level.

The PDF includes a summary in Finnish.

• Heikurainen, E-mail: lh@mm.unknown

The purpose of this paper is 1) to establish the possible seasonal variation of the different phases of work in the sawmill industry in Finland, 2) to study the internal and external factors influencing the seasonal character of the sawmill industry, 3) to study ha time lags between the work phases of the sawmill industry, 4) to analyse the seasonal nature of the industry’s money transactions, and 5) to give information concerning the factors influencing employment. The investigation is based on questionnaires of a random sample of sawmills concerning the time period of 1958-1960. This paper concentrates on the methods of the study, the results are reported in a separate paper in the Acta Forestalia Fennica issue 75 vol 1.

It was concluded that if seasonal variation in the sawmill industry is to be analysed on the scale it has been in the present work, sampling is the cheapest and most practicable method of collecting the material. If seasonal fluctuation of the industry is to be calculated by size classes, the sample must be allocated into strata by measuring the heterogeneity of the classes with a parameter illustrating seasonal variation. It might be useful to apply these parameters already when the total size of the sample is determined. For the smallest sawmills, for which practically all data have to be collected from primary documents, the most practical method is perhaps to send collectors to the spots. To the larger sawmills the questionnaire can perhaps be sent by mail. A moving index should be obtained for calculation of a seasonal index, but this demands long time series. The collection of the data is described in detail.

The PDF includes a summary in English.

• Ervasti, E-mail: se@mm.unknown

The objective of this study has been to discover some of the basic principles on which an increment for a large forest area might be forecast. Because the stands in a large forest area vary considerably in density and are subject to different kinds of treatment, the main interest falls on the stand characteristics which determine the increment percentage in such forest conditions as these. The material used in the study has been published earlier, it consisted of sample plots of Scots pine (Pinus sylvestris L.) stands (Nyyssönen 1954).

Increment functions are of great importance in the increment forecast for cutting budget. Because 60-80% of the variation in the increment percentage can be explained by stand characteristics in circumstances where the age of the stand is 40-130 years and the volume vary with a coefficient of variation 0.6-0.7, regression equations for increment percentage may be based on a number of sample plots smaller than in a growing stock inventory in the same conditions. It is possible to get accurate results with relatively small number of sample plots. Furthermore, the smaller amount of increment sample plots makes it possible to develop measurement techniques.

The increment functions enable study of increment as a biological process. However, conclusions about biological process on the basis of regression equations should be made with caution. Still, regression analysis is a powerful tool in yield studies.

The PDF includes a summary in Finnish.

• Kuusela, E-mail: kk@mm.unknown
• Kilkki, E-mail: pk@mm.unknown

It is necessary to study the problems related to the size, number and location of sample plots as well as to the effect of stratification. This paper, mainly concerned with the volume of the growing stock based on measurements, comprises a part of the research in progress related to the issue.

The study contains a discussion of certain problems relevant to the planning of a forest inventory on the basis of variation in the volume of the growing stock. In particular, the aim has been to give data for selection of the size and number of sample plots, and to illustrate the importance of stratification, here based principally on dominant height.

The research material comprised two forest areas of 10 ha each; measurement of the growing stock was made in units of 49 m². Based on the data was constructed a model area embracing 4 forested strata and one non-forested stratum. The mean and standard deviations of the volumes was calculated for the forest area as a whole and for the different strata. On studying stratification, two approaches were employed to distribute the sample plots among the strata: optimum allocation and proportional allocation. The latter is simple in application, and gave for forested areas number of sample plots which did not exceed by more than 10% those obtained by optimum allocation. It is obvious that the application of stratification is worthy of consideration within forest areas which comprise parts with distinct differences. The decrease in number of plots with increasing plot size is considerably more marked within a stratified area. Thus, larger sample plots should be used in the former case than in the later. The investigations give hints on how forest inventories should be carried out. However, it has some limitations, which are discussed in the paper.

The PDF includes a summary in English.

• Nyyssönen, E-mail: an@mm.unknown
• Vuokila, E-mail: yv@mm.unknown

Short run market forecasting is desirable both for adjusting production and for regulating the national employment policy. In this study a forecast is made for one product. The purpose of the study is to develop a short run model describing newsprint sales in Finland that will combine mathematical simplicity, accuracy of description and universality.

Two methods of selecting variables seemed to be available. According to the first, newsprint consumption is divided into components, each of which is considered separately. The second method, which proved more fruitful, starts out directly from factors influencing the publishers’ decisions in purchasing newsprint, eliminating the least significant intuitively and simultaneously determining the lags.

The models developed in this study are capable of forecasting potential consumption. Even the best models in this study are multicollinear. The further into the future a forecast is extended, the greater is the possibility that relationships between the explanatory variables will change. It is intended that the newsprint seller will profit from the models achieved by using them to forecast sales in a future period, so that he can avoid both loss of interest due to acquiring a surplus of raw material or acute shortages of raw material.

The PDF includes a summary in Finnish.

• Riihinen, E-mail: pr@mm.unknown

Because the ‘rental cut method’ is rather arduous and based partly on subjective analysis, new forms for a cutting budget has been developed. One of them is a method called stock development forecast, and another method will be described in this paper. The main characteristics of the present growing stock affecting the allowable cut are the forest area, site quality, forest composition by age and development classes, volume, and increment.

In the method described in this paper an analysis of the desirable stock is necessary. The allowable cut is a function of the current and desirable stock and the increment during the budget period. The budget is based on information about the forest area, site quality, growing stock and its structure, collected from an inventory. The desirable stock is described in the same sub-groups as is the current stock. An increment forecast is prepared by compound and an interest formulae and increment percentages are presented as a function of the stock age. The allowable cut shows the average amount of the cut during the management plan period.

The PDF includes a summary in English.

• Kuusela, E-mail: kk@mm.unknown
• Nyyssönen, E-mail: an@mm.unknown

The annual fellings and sales of pulpwood from the State Forests of Finland comprised 4.0–4.6 million m³ in 1955–1959. In order to improve the accuracy of the methods used in estimating the pulpwood stocks marked for felling, a pilot survey of 18 marked stocks was carried out in 1959. The stock area, average plot volume, variation of the plot volumes, size and shape of the plot and the distribution of the trees by diameter classes as factors affecting the precision have been studied in this paper.

The greater the mean volume of a plot the more homogenous is the structure of the marked stock. The same number of plots gives a better relative precision for the south Finnish marked stock than for the north Finnish ones, which are heterogenous and less valuable. Stocks smaller than 50 ha can often be estimated more advantageously by the strip method or visually than by the plot method. The proper size of plot in Southern Finland is 0.02–0.03 ha. In Northern Finland the plots should be larger due to the heterogenous stocks, about 0.05 ha. The shape can be either circular or rectangular. The former may be more practical and reliable in the field. The minimum number of sample trees is considered to be about 200 per 100 sample plots 0.03 ha in size.

The PDF includes a summary in English.

• Kuusela, E-mail: kk@mm.unknown

The purpose of the investigation was to study the characteristics of the site and the growing stock and the effect of their variation on the precision of forest inventory. The total area of the forest tract is considered to be already known or it can be measured with surveying. The sub-areas or strata and the mean timber volume of each wooded stratum are estimated by sampling. Thus, the total volume of each stratum is the product of the estimates of the area and mean volume. Only line method of sampling the areas will be examined. Field material was measured in the inventory of the Finnish State Forests with the method used in the third National Forest Inventory. The circular plots and the sample trees were measured in the forests of Inari district. In this systematic line-plot method the distance between the lines was 5 km.

The results show that the total area should be broken down into suitable strata, such as the full-stocked productive forest land and regeneration areas with mother trees. The mean volume for each stratum is estimated with the plot method. An advanced estimation of the approximate mean volume and the coefficient of variation in the strata are needed for calculating the optimum allocation of plots.

If the volume calculation is done with the diameter as variable the variation of the plot volumes is decreased. If the local volume table is used and the site and stock characteristics differ from the characteristics of the volume table stock, a significant systematic error is possible. Planning of efficient and economical forest inventories requires data concerning site and stock variation. It should be calculated and published systematically by geographical region.

The PDF includes a summary in English.

• Kuusela, E-mail: kk@mm.unknown

Decomposition of the peat using von Post Humification Scale (1–10), developed by Lennart von Post, can be determined based on characteristics of peat, such as fibre integrity, colour and viscosity of exudate, and presence of colloidal particles, of handful of peat squeezed in the hand. It is easy to use and has proved useful in the practical work. The method developed by Pjavthenko is mostly based on specific weight off a dried sample in percentage, and requires analysis in the laboratory. The aim of this study was to compare the results of these two methods by measuring 156 peat samples representing different stages of decomposition.

The methods are based on different principles, which is reflected in small differences of the results. The maximum scores of the methods are clearly in different level. The maximum grade of 9–10 in von Post scale correspond decomposition percentage 51 in the scale of Pjavtsheko. However, the decomposition values in von Post scale are placed evenly on the scale of Pjavtshenko. This suggests that the von Post Scale is consistent and accurately developed. According to the study, the Pjavtshenko method is a good method to validate results of von Post Humification Scale, and can be used when decomposition of peat samples is determined in laboratory.

The PDF includes a summary in German.

• Sarasto, E-mail: js@mm.unknown

Especially in experimantal ecological research it is used small sample plots that are inventoried consequently. The paper describes a method for establishing small sample plots, developed by the writer in 1956. In the method, the central point of the sample plot is marked with an iron skewer, and the marking of the area to be inventoried was accomplished with a circular frame that is movable. The frame was fitted to the skewer with an aperture that indicated the central point. The area of the frame was relatively small, 0,25 m². The sample plots were arbitarily placed at intervals from one another.

The PDF includes a summary in Finnish.

• Yli-Vakkuri, E-mail: py@mm.unknown

The investigation is divided into statistical and experimental sections, the latter of which were conducted in a Vaccinium type Scots pine (Pinus sylvestris L.) stand with the aim of elucidating the interdependence of soil humidity and meteorological factors. The moisture content of pine needles and moss and wooden cylinders placed on the soil or slightly over the ground was determined by weighing. The results showed that there is correlation between the moisture content of the wooden cylinders and the relative humidity of air during the days without rain. Correlation between moisture content of pine needles and moss with the air was slightly poorer.

In the statistical section, based on meteorological observations made in the geophysical observatory at Sodankylä in Northern Finland in 1920-1943, and forest fire statistics of the area, forest fire days and days without forest fires were divided into 40 temperature-humidity groups. Of the 391 forest fires observed in the area, the cause of the fire was known in 353 cases, and 69% of these were caused by lightning. A forest fire danger index was calculated using the data. A sharp increase in the burned area when the index exceeded the limit k=0.3 seem to be explained by thunderstorms, which are the most notable cause of forest fires in the Sodankylä area.

The forest fire index was calculated also at four meteorological stations in different parts of the country using weather observations in 1927-1936. It appears that the number of days in which the k>0.1 decreases when proceeding northwards, obviously because of the shortening of the summer. On the other hand, the number of days in which k>0.3 increases towards the north.

The PDF includes a summary in English.

• Franssila, E-mail: mf@mm.unknown

The article introduces methods that can be used to calculate economic profitability of draining of peatlands, and discusses their advantages and weaknesses. The time span from draining of a peatland and the future income is usually decades, which makes it difficult to assess profitability for the investment. For instance, income from future fellings depends on chosen rotation time, and price of timber that can fluctuate strongly.

When calculating the profitability, the drained area can be treated as a separate unit of account or as a part of the forest holding. In the first case, several methods can be used. First, yield in terms of value is a suitable method only if the peatland has no existing forest. Second, annual yield of a drained peatland and peatland in natural state can be compared. In this case yield can be defined in several ways. Third method uses value increment of the growing stock. Fourth method estimates value of increment for both the growing stock and land. Fifth method is based on present value of the future felling income, and sixth on actual value of the growing stock and yield in terms of value.

The PDF includes a summary in German.

• Saari, E-mail: es@mm.unknown

Forest management practices have deployed during the centuries very differently in different regions. The geographical as well as other nature related factors influence them heavily. During the first half of 19^th century was shelterwood felling much used practice especially in Prussia. Meanwhile the clearcutting with planting the seedlings became also more popular. The method is still widely used in many countries. Becoming more popular the clear cut and planting practice changed the modus operandi of forestry from close-to-nature to economically-oriented.

• Aaltonen, E-mail: va@mm.unknown

Two methods of pre-harvest inventory were designed and tested on three cutting sites containing a total of 197,500 m³ of wood. These sites were located on flat-ground boreal forest in north-western Quebec, Canada. Both methods studied involved scaling of trees harvested to clear the road path one year (or more) prior to harvest of adjacent cutblocks.

The first method (ROAD) considers the total road right-of-way volume divided by the total road area cleared. The resulting volume per hectare is then multiplied by the total cut-block area scheduled for harvest during the following year to obtain the total estimated cutting volume. The second method (STRATIFIED) also involves scaling of trees cleared from the road. A volume per hectare is calculated for each stretch of road that crosses a single forest stand. This volume per hectare is then multiplied by the remaining area of the same forest stand scheduled for harvest one year later. The sum of all resulting estimated volumes per stand gives the total estimated cutting-volume for all cut-blocks adjacent to the studied road. A third method (MNR) represent the actual existing technique for estimating cutting volume in the province of Quebec. It involves summing the cut volume for all forest stands. The cut volume is estimated by multiplying the area of each stand by its estimated volume per hectare obtained from standard stock tables.

When the resulting total estimated volume per cut-block for all three methods was compared with the actual measured cut-block volume (MEASURED), the analysis showed that MNR volume estimate was 30% higher than MEASURED. However, no significant difference from MEASURED was observed for volume estimates for ROAD and STRATIFIED methods, which respectively estimated cutting volumes 19% and 5% lower than MEASURED.

• Morasse, E-mail: jm@mm.unknown

Biogeographical patterns of the Scolytidae in Fennoscandia and Denmark, based on species incidence data from the approximately 70 km x 70 km quadrats (n = 221) used by Lekander et al. (1977), were classified to environmental variables using multivariate methods (two-way indicator species analysis, detrended correspondence analysis, canonical correspondence analysis).

The distributional patterns of scolytid species composition showed similar features to earlier presented zonations based on vegetation composition. One major difference, however, was that the region was more clearly divided in an east-west direction. Temperature variables associated with the location of the quadrat had the highest canonical coefficient values on the first axis of the CCA. Although these variables were the most important determinants of the biogeographical variation in the beetle species assemblages, annual precipitation and the distribution of Picea abies also improved the fit of the species data.

Samples with the most deviant rarity and typicality indices for the scolytid species assempblages in each quadrat were concentrated in several southern Scandinavian quadrats, in some quadrats in northern Sweden, and especially on the Swedish islands (Öland, Gotland, Gotska Sandön) in the Baltic Sea. The use of rarity indices which do not take the number of species per quadrat, also resulted high values for areas near Stockholm and Helsinki with well-known faunas. Methodological tests in which the real changes in the distribution of Ips acuminatus and I. amitinus were used as indicators showed that the currently available multivariate methods are sensitive to small faunal shifts even, and thus permit analysis of the fauna in relation to environmental changes. However, this requires more detailed monitoring of the species’ distributions over longer time spans.

Distribution of seven species (Scolytus intricatus, S. laevis, Hylurgops glabratus, Crypturgus cinereus, Pityogenes salasi, Ips typographus, and Cyleborus dispar) were predicted by logistic regression models using climatic variables. In spite of the deficiencies in the data and the environmental variables selected, the models were relatively good for several but not for all species. The potential effects of climate change on bark beetles are discussed.

The PDF includes a summary in Finnish.

• Heliövaara, E-mail: kh@mm.unknown
• Väisänen, E-mail: rv@mm.unknown
• Immonen, E-mail: ai@mm.unknown

Multivariate methods are used to classify pine mires on the basis of edaphic properties into fertility groups in order to estimate the effect of fertilization in relation to site fertility. The data is based on two field inventories of NPK fertilization experiment in which 2,624 sample trees on 164 sample plots from 19 experimental fields were measured on Scots pine (Pinus sylvestris L.) dominated stands. The edaphic properties (total contents of nutrients and related properties) are based on 1,350 volumetric sub-samples of fertilized and non-fertilized control plots.

In a DECORANA ordination, based on standardised volumetric soil variables N-P and acid-base gradients jointly describing trophic status were distinguished. Mainly on the basis of these two gradients a TWINSPAN analysis divided the material into five edaphic groups. To independently allocate sample plots into fertility groups, discriminating multiple regressions were formed using the TS edaphic groups as class variable.

The effect of N, P, K, NP, NK, PK, and NPK treatments on tree growth was estimated on the basis of change in relative basal area increment during two growth periods. During five-year period immediately after fertilization N and P treatments evoked the strongest increase in growth. On the nutrient poor sites, the effect was almost double that on the fertile sites. The effect of N was short lasting while the P treatment still affected growth after 5–11 years. Although K treatment had little influence on tree growth needle samples collected 11 years after fertilization indicated increased K uptake on fertilized plots.

Generally, the effect of fertilization on absolute stand volume growth was small. During the 11-year study period the total increase in growth gained with NPK was some 3–4 m³/ha. Despite strong relative response of individual sample trees, due to low stand volume fertilization (and drainage) had practically no effect on volume growth on the sites of lowest fertility.

The PDF includes a summary in Finnish.

• Westman, E-mail: cw@mm.unknown

Analysis of sample tree data showed that the major part of the residual variation of the stem volume estimates occurs within the forest stands. The division of the residual variation into the variation within and between populations is the basis for the mean-square error formulae of the volume estimators. Efficiency of different sample tree measurement combinations has been studied by comparing the errors of the volume estimates to the sampling costs. The measurement of the upper diameter (d6) is of less value than is generally suggested.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown

The possibilities of using microwave techniques in detecting the trafficability of peatlands is discussed. Three microwave methods were tested. 1) A FM-CW radar using 1.0–1.8 GHz frequency was used to measure the frost thickness of peat layer. It was possible to follow the variations in snow and frost layer thickness. Total reflected power might indicate the wetness class of the peatland, which is also a trafficability factor. 2) A short-pulse radar with 100 MHz frequency was tested in summer condition. Good profiling of peat layers was obtained, giving basic information for trafficability analysis. 3) A mapping of brightness of temperature of peatlands in summer conditions using a 790 MHz radiometer. The measured brightness temperature was correlated with vegetation cover, thus giving some information of trafficability.

The PDF includes a summary in English.

• Saarilahti, E-mail: ms@mm.unknown

Taper curve models based on simultaneous equations were derived. The data consisted of 492 Scots pines (Pinus sylvestris L.) from Southern Finland. Two systems of simultaneous equations were constructed, one without the crown ratio and the other with the crown ratio as an exogenous variable. The endogenous variables consisted of 24 relative-height diameters and the height of the tree. The parameters of the model were derived by the ordinary least squares method.

In most applications, the height of the tree was exogenised. The logarithmically linear relationships between the relative-height diameters were utilized in the solution algorithm. The algorithm included both standard matrix operations and an iterative part in which the taper curve was fitted to any measured diameters by the natural cubic spline interpolation formula.

The models were applied to the derivation of taper curves, stem volumes, timber assortment percentages, and stem values. An experiment was also made to derive diameter and height increments from the taper curve model.

The reliability of the models was tested on the original data.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown
• Varmola, E-mail: mv@mm.unknown

The purpose of this study was that of providing a long-term timber production model (Kilkki and Pökkälä 1975) with growing stock models. The paper is divided into two parts; the first is concerned with generation of the stand data through Monte-Carlo simulation. The growing stock of each stand was described by a DBH-height distribution. The necessary information on the relationships between the stand characteristics was derived from sample plots measured in the national forest inventory of Finland. A total of 1,500 Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst), and birch (Betula sp.) stands, each comprising 100 trees were provided by simulation.

In the second part, models predicting the form factor, timber assortment distribution, and value of the growing stock were derived through regression analysis for each species of tree. The predicting variables included the form factor of the basal area median tree, basal area median diameter, and height in the form factor models. In the timber assortment and value models, the only predicting variable was the volume of the basal area median tree. The Matchcurve-technique (Jensen 1973) was employed in derivation of the regression models.

The PDF includes a summary in English.

• Kilkki, E-mail: pk@mm.unknown
• Siitonen, E-mail: ms@mm.unknown

A long-term timber production model was developed. The model is based upon numerical simulation and it is viewed only as a means of providing the decision-maker with values of the predicting variables in his utility function. Special attention was paid to the development of automatic cutting decision rules. The model was applied to the area of 2,752,000 hectares of forest land in Central Finland. The measurement data were extracted from the Sixth National Forest Inventory, which was made in 1973. Utilities from a hypothetical utility function were attained to a number of feasible timber production policies. The Bayes and maximin criteria were employed to evaluate these policies.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown
• Pökälä, E-mail: rp@mm.unknown

Production of timber in forest stands is described by a production function. The variable inputs of the function are land and growing stock and the output is the annual value growth. The partial derivatives of this production function express the marginal productivity of the land and of auction function express the marginal productivity of the land and of the growing stock. These marginal productivities can be utilized for determination of the need of regeneration and thinning. The stand should be regenerated when the marginal productivity of the land falls below the annual rent of a unit area of open land and thinned when the marginal productivity of the growing stock falls below the annual rent of one unit of growing stock.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown

This study is concerned with silvicultural selection from above. The material consists of 18 Scots pine (Pinus sylvestris L.) sample plots in the southern half of Finland in experimental forests. The method is motivated by the great difference between the stumpage prices of saw timber and pulpwood. The method suggested includes the removal of individuals belonging to the predominating canopy, to achieve high levels of income from the stand at an early stage. The method is applied at when the growing stock is attaining saw-timber size. Before that the stand is treated with thinnings from below. It is supposed that the volume of growing stock is maintained at a level as high as that in below-thinned stands, and that rotation is of normal length.

On the average, the increment in basal area, as well as volume increment, is greater in stands selectively cut from above than in those treated with low thinnings of the same degree. Initially, selection from above seems to exert a negative effect upon the development of dominant height; later, the dominant height reassumes the same rate of increment as in the below-thinned stands. Selection from above also means an increase in saw-timber production, although it involves a reduction in the mean size of saw timber. The investigation includes growth and yield tables for pine stands treated with silvicultural selection from above.

The results of the investigation prove that silvicultural selection from above is at least as profitable as low thinning. This provides freedom for stand treatment, and contributes to the application of a method most suitable for the owner in each individual case. It is further stressed that the maintenance of a high wood capital in the stand is far more important than the method of thinning applied.

The PDF includes a summary in English.

• Vuokila, E-mail: yv@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.

• Kärkkäinen, E-mail: mk@mm.unknown

This paper is a report of the authors visits to over 80 forestry nurseries in 20 countries mostly in the tropics or subtropics. The article aim is to describe the methods used in the various countries and compares them to the conventional methods of cool and temperate countries. The article introduces nurseries of Africa south of the Sahara, Mediterranean area, Australian and New Zealand and Latin America.

A complete revolution has taken place in the Finnish nursery practice, which used to raise the seedlings in natural field soil in open-air nurseries. The seedlings were usually transplanted into transplant beds at the age of two years. Now the use of plastic greenhouses of light construction and an artificial soil substrate (fertilized peat) are essential. The new technique has some similarities to the practises of the tropical and subtropical nurseries. In Finland cultivation in greenhouses has hastened the development of the seedlings and shortened the nursery rotation from four to two years, and provided better control of watering and fertilization.

Peat beds in greenhouses are used also in Swaziland. The advantage of peat is that it is free of weed seeds, which eliminates weeding. Peat substrate gives also better yield of seedlings, which decreases the need of seeds, which is important in Finland. Another technique common with tropical silviculture is the production of potted seedlings, which are easy to handle and transport. In tropics, peat pots (jiffy pots) have made it possible to grow plantable seedlings in one season without transplanting. The present Finnish technique means a decreased degree of mechanization compared to the conventional technique of modern European and American nurseries.

• Mikola, E-mail: pm@mm.unknown

The aim of this study was to develop cutting budget methods for a forest undertaking. Cutting budget provides information on the future income from the forest undertaking, and on the development of the forest.

Two cutting budget models have been developed, by the application of simulation and linear programming. Both of the models are deterministic in nature, i.e. there is only one possible outcome once the stated input information has been given. To make the models simpler, it has been assumed that thinning and clear cutting with reforestation are the only activities that can occur in the forest. The models are directly applicable only to forests consisting of even-aged Scots pine stands at three different forest types. However, they can easily be extended to cover forests comprising several tree species and more sites.

In the light of this study, simulation seems today to be more appropriate than linear programming in the preparation of cutting budgets. However, the increasing capacity of computers may even in the near future make linear programming quite competitive, especially as if it is borne in mind that the theoretical basis of linear programming is much firmer than that of simulation. The most advisable cutting budget method might consist of a combination of simulation and linear programming. Simulation could be employed to find a rough cutting schedule, and linear programming to test and improve the solution.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown

The purpose of the present investigation was to study the extent of human interference with the forests of different epochs in the district of north Ostrobothnia in Northern Finland, and its effect on the condition of the forests.

The study revealed that the quantities of wood removed were not most detrimental to the condition of the forest; the regionally irregular loggings and the logging methods employed were the most harmful. The old forms of wood utilization, tar industry, shipbuilding, sawmill industry and timber exports, were characterized by timber selection. Public opinion considered it the only recognized cutting method long after the conditions had changed and silvicultural methods should have been used.

The spread and abandonment of selection cuttings are illustrated in the results of first National Forest Surveys in Finland. According to the first survey (1921–1924), nearly half of the loggings in the province of Oulu were based on selection, which spoiled and devastated 41% of the forests. In the 1930s one-fifth of the North Ostrobothnian forests were weakened by selection cuttings, in 1960s the figure was 6%. The article also summarises the extent of tar and pitch production, sawmill industry, shipbuilding and household wood consumption of wood in the area.

The PDF includes a summary in English

• Alho, E-mail: pa@mm.unknown

This is a fourth paper in a series of studies concerning logging in farm forests. The objective was to construct a model representing the productivity per farm of logging for delivery cuts. The first objective was to find out how the productivity of logging should be measured. In the study, combined labour and capital are regarded as the input.

Second object was to consider what variables to use in theory to determine the productivity of logging for delivery cuts. The factors affecting productivity depend on the concept of productivity employed. The productivity per farm of logging in delivery cuts can be determined both by regional and by farm variables. Still considering solely the effect of the quality of labour and capital input, the variables representing the person in charge of the delivery cuts are important explanatory farm variables. Others represent the farm totality (size, lines of production etc.).

Third aim was to develop a statistical-mathematical method suitable for constructing the model. Possible methods include regression analysis, which is, however, not the best method when there is large number of different levels to explain, or factor analysis. The suitable method to use in constructing a model depicting the productivity of a farm, was considered to be to condense the explanatory variables into rotated orthogonal factors. After preliminary correlation analysis, estimates of the factors interpreted as rational were employed as the explanatory variables for selective regression analysis.

Last, the model was tried out against actual material collected per farm, and the hypotheses were tested.

The PDF includes a summary in English.

• Mäkelä, E-mail: jm@mm.unknown

• Luostarinen, Faculty of Forest Sciences, University of Joensuu, P.O. Box 111, FI-80101, Joensuu, Finland E-mail: katri.luostarinen@joensuu.fi
• Huotari, Finnish Forest Research Institute, Muhos Research Unit, Kirkkosaarentie, FI-91500 Muhos, Finland E-mail: nh@nn.fi
• Tillman-Sutela, Finnish Forest Research Institute, Muhos Research Unit, Kirkkosaarentie, FI-91500 Muhos, Finland E-mail: ets@nn.fi

• Haara, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: arto.haara@joensuu.fi
• Leskinen, Finnish Environment Institute, Research Programme for Production and Consumption, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: pl@nn.fi

• Siipilehto, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: jouni.siipilehto@metla.fi
• Sarkkola, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: ss@nn.fi
• Mehtätalo, University of Joensuu, Faculty of Forestry, P.O. Box 111, 80101 Joensuu, Finland E-mail: lm@nn.fi

• Laukkanen, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: sanna.laukkanen@joensuu.fi
• Palander, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: tp@nn.fi
• Kangas, UPM-Kymmene Forest, P.O. Box 32, FI-37601 Valkeakoski, Finland E-mail: jk@nn.fi
• Kangas, University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: ak@nn.fi

• Haara, Finnish Forest Research Institute, Joensuu Research Centre, P.O.Box 68, FIN-80101 Joensuu, Finland E-mail: arto.haara@metla.fi

• Brække, Department of Forest Sciences, Agricultural University of Norway (AUN), P.O. Box 5044, N-1432 Ås, Norway E-mail: finn.braekke@isf.nlh.no
• Salih, Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences (SLU), P.O. Box 7072, S-750 07 Uppsala, Sweden E-mail: ns@nn.se

• Poso, Department of Forest Resource Management, P.O. Box 24 (Unioninkatu 40 B), FIN-00014 University of Helsinki, Finland E-mail: simo.poso@helsinki.fi
• Wang, Department of Forest Resource Management, P.O. Box 24 (Unioninkatu 40 B), FIN-00014 University of Helsinki, Finland E-mail: gw@nn.fi
• Tuominen, Department of Forest Resource Management, P.O. Box 24 (Unioninkatu 40 B), FIN-00014 University of Helsinki, Finland E-mail: st@nn.fi

• Modig, Statens fastighetsverk, Jokkmokk, Sweden E-mail: em@nn.se
• Magnusson, Skogsstyrelsen, Bräcke, Sweden E-mail: bm@nn.se
• Valinger, Deparment of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden E-mail: ev@nn.se
• Cedergren, Mariehamn, Åland E-mail: jc@nn.se
• Lundqvist, Deparment of Forest Ecology and Management, SLU, SE-901 83 Umeå, Sweden E-mail: lars.lundqvist@slu.se