Current issue: 58(5)
Articles containing the keyword 'statistic'
Category : Article
The existence and direction of causal relationships between the time series for the Finnish roundwood market for the period 1960–1994 is tested. Using simple bivariate analysis, we found evidence that for both logs and pulpwood, the lagged prices are helpful in forecasting quantity for the next year, but not vice versa. Saw log stumpage prices have significantly Granger-caused pulpwood prices over the business cycles, but the effect has diminished towards the present time. For quantities traded, the direction of causality was rather from pulpwood to saw logs. The consistency of bivariate test results was checked by the Granger-causality tests within trivariate VAR-models for both markets, and the results were found to be fairly similar to bivariate tests. The price fluctuations in the international markets for forest products have been found to be carried to domestic wood markets dominantly via the pulpwood part of the market.
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Toppinen,
E-mail:
at@mm.unknown
The first aim of this study was to develop a simulation model describing the flow of different timber qualities to different firms. The second aim was to study preliminary the factors which affect timber distributions. In addition, we tested the hypothesis that in a small sawmill firm the traditional way of organizing timber procurement does not direct effectively good quality logs to the special production. The game theoretic approaching and the principles of Monte-Carlo simulation were applied in development of the simulation model. The most important factors of the model were tried to find for further studies with sensitive analysis. Empirical validation brought forth promising results in the area of one municipality. The buyer’s awareness of a marked stand, the seller’s willingness to sell a marked stand, the buyer’s ability to pay for wood and the proportion of first quality pine logs in a marked stand affected the distribution of pine logs. The results also supported the hypothesis that the traditional system, in which sawmills or their own forest departments procure themselves all timber needed, is not the most effective way to direct enough good quality timber to the special production.
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Tolvanen-Sikanen,
E-mail:
tt@mm.unknown
- Harstela, E-mail: ph@mm.unknown
- Sikanen, E-mail: ls@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.
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Schabenberger,
E-mail:
os@mm.unknown
- Gregoire, E-mail: tg@mm.unknown
Tree height data from 33 progeny trials of Scots pine (Pinus sylvestris L.) were used to determine the effect of within-plot subsampling on the magnitude of statistically detectable differences between families, family heritability and correlation of family means based on different sample sizes. The results indicated that in trials established with a standard plot configuration of 25 trees per plot, measuring only 10–15 trees gives nearly the same precision as with assessment of all the plot trees. Even as few as 4–6 trees assessed per plot may constitute a sufficient sample if families or parental trees of extreme performance are being selected. Trials established with non-contiguous plots were found to be more efficient than those established using multiple-tree contiguous plots.
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Haapanen,
E-mail:
mh@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
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Haapanen,
E-mail:
mh@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.
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.
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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.
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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.
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Hahtola,
E-mail:
kh@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.
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Mäkelä,
E-mail:
jm@mm.unknown
The ministry of agriculture appointed a committee to prepare a proposal for the reorganization of Finnish forest statistics. The committee suggests that the forest statistics will be prepared by forest district board areas. National forest surveys and national wood consumption surveys should be carried out at intervals of 10-15 years by Forest Research Institute.
Felling and price statistics for private forests should be prepared by using a sampling method described in the report. The statistics of total commercial roundwood felling will be obtained by adding to the result the annual felling from state and company forests. Also, wage and employment statistics in forestry will be prepared by a sampling method.
Statistics concerning timber transportation should be improved, and finally, a central organ for forest statistics should be established within the Forest Research Institute to collect and develop forest statistics. The statistics should be published as an annual yearbook. To ensure co-operation between the authorities, a special sub-committee should be appointed to collaborate with the permanent committee of statistics in Finland.
According to the second National Forest Survey, peatlands covered before the World War II 11,156,000 hectares, 32% of the land area of Finland. The early drainage of peatlands in 1700th century had aimed at preventing frost and increasing area of agricultural land. The experiences proved that drainage of wet forests was lucrative also in the point of view of forestry. The drainage of state-owned forest lands was promoted by the Crown Forest Committee in its report in 1900. The systematic drainage work in state lands begun in 1909. In the end of 1920s 500-700 km of ditches was dug annually.
The drainage of private lands begun after 1928, when forestry promotion work in private forests begun. By the end of 1950, 4,815 forest drainage projects had been approved by the Forest Service in the private lands. In addition, 286,000 ha of peatlands was drained on work organized by the central forest associations in 1930-1950, and 239,272 ha by timber companies in 1902-1950. The drained area totalled 755,892 ha. The area of drainable and drained peatland was estimated to be 4.4 million ha.
The article includes an abstract in English.
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Tirkkonen,
E-mail:
ot@mm.unknown
Silva Fennica Issue 69 includes presentations held in 1948-1950 in the fourth professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation introduces different forestry related statistics and discusses the potential use of statistics on the point of view of state forestry.
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Ennevaara,
E-mail:
pe@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.
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Aro,
E-mail:
pa@mm.unknown
Silva Fennica Issue 39 includes presentations held in professional development courses in 1935 that were arranged for foresters working in public administration. The presentations focus on practical issues in forest management and administration, especially in regional level.
This presentation lists statistics available on forestry.
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Saari,
E-mail:
es@mm.unknown
The Forest Research Institute made an investigation on the wood consumption in Finland in 1927. This work brought up a need to organize continuous collection of statistics of wood consumption. Three kinds of existing statistics can be used: statistics of wood consumption, statistic of the fellings, and statistics of transport of wood.
Statistics on wood consumption, such as the fuel used by the industry and State railways are collected annually. The fellings in state forests are published annually, and also the wood manufacturing companies publish statistics of their forests. Furthermore, all fellings on sale, and use of own wood in wood manufacturing industry have to be reported to the forestry committees. These statistics are published annually. Railroads and floating are the main means of long distance transport of wood. These statistics give additional information of wood consumption. Further studies are needed to combine and standardize the statistics collected from different sources.
The PDF includes a summary in English.
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Saari,
E-mail:
es@mm.unknown
Category : Article
Roundwood statistics are essential in a country such as Finland, where the roundwood market costitutes one of the most important internal markets. Determining the price level of roundwood can, however, be problematic due to the difficulty of the empirical determination. The main difficulties are the many timber assortments, quality differcences within a timber assortment, large variation of local prices due to variations in demand and harvesting conditions and in sales methods. The article discusses these problems from the perspective of composing a roundwood statistics for different timber assortments that would allow local and temporal comparison of the prices. It seems impossible to compose price statistics that could eliminate totally the variation in the material, transport conditions and demand fluctuations caused by technical development. However, one can suffice to a compromise that would eliminate the major disturbances and take into account other factors that are not related with market when studying the price series. In addition, the paper discusses methods for calculation of price indices.
The PDF includes a summary in Finnish.
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Holopainen,
E-mail:
vh@mm.unknown
Work studies conducted in Finland and Sweden on forest work have shown that the performance of different workers or even of a same worker vary greatly, although external conditions such as the size and other properties of the trees, weather etc. are similar. It has been decided in the Northern Countries that as it is impossible to assess the working speed of a man, it is not possible to find out the average work performances, not even from long term time studies. The only way is to collect performance statistics.
Metsäteho (Forest Work Studies Section of the Central Association of Finnish Woodworking Industries) has collected since 1946 statistics on the working sites of forest industry companies in different parts of Finland on the preparation on timber. To make it comparable the material has been converted to uniform values by using the ratios given by the work time studies of various forest jobs conducted by Metsäteho. The ratios are necessary in trying to determine average performances by statistical means. The actual length of time each man is at work on different days and the actual number of days is needed, because in Finland the workers can themselves decide fairly freely the length of a working day. In forest work, wages are paid for the quantity prepared, not for time. The statistics collected by Metsäteho include information on the length of the working days, and conditions in each forest, such as the size of the trees, form of stem, branchiness, bark thickness, terrain, density of the forest, weather conditions etc.
The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.
The PDF includes a summary in English.
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Vöry,
E-mail:
jv@mm.unknown
The mean has a great importance in statistics in general and also in forest statistical calculations. The meaning of the average tree and its characteristics is important also for the practical forest mensuration work. However, the question is how are the statistical numbers of a mean tree related to the statistical numbers of the stand.
Study is based on the strip-wise survey of forests in southern Finland. From that information the 30 sample plots were chosen, 10 of each of most typical forest site types, MT, VT and CT. The stands are of different ages and development classes, varying from 14 to 159 years.
For the determination of the average tree are the statistical numbers of five characteristics needed: volume, basal area, diameter, height and form factor. The stereometric mean tree of the stand can be calculated with only one statistical method and that solution is absolute.
Theoretically and statistically absolute solution for the problem is the continuous solution by the mean that is weighted with the number of stems. This solution however is not very useful in practical sense.
A simple, practical and adequately exact solution for determining the average tree by approximation procedure of a certain arithmetic mean.
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Lönnroth,
E-mail:
el@mm.unknown
The article statistically studies the vegetation patterns in different forest types.
467 sample plots with area varying from one fourth of a hectare to one eighth, even one tenth of a hectare were collected. There are different amount of sample plots representing every forest type. The sample plots are located in 58 communes in southern parts of Finland, reaching from the Gulf of Finland up to Oulujärvi –see in northern Ostrobothnia. The vegetation was examined from rectangle shaped study plots in even structured and even-aged stands with one primary tree species.
The results are shown in tables for every forest type. The amount of species is at highest in the most nutritious forest types, and decreases with the shift to more infertile types. However, some species occur in all forest types, and some only or mostly on more barren types. The occurrence and abundance of most plant species does not seem to depend on the tree species of the stand, but there are some exceptions to this.
The possible shortcomings of the research method are discussed. The importance of systematic studying of the sample plots with a method of survey lines is emphasized.
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Ilvessalo,
E-mail:
yi@mm.unknown
The article includes a program for an investigation concerning land purchases by the forestry companies in Finland, requested by the Finnish Forest Association in 1917. The paper draws detailed principles for collecting a comprehensive, accurate and objective information of land purchases of the industry, as well as land holdings, farms and forest lands owned by the companies. Finally, it gives suggestions on how to correct the observed problems in the land purchase, and how to balance the conflicts of interests between the different branches.
The PDF includes a summary in German.
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Renvall,
E-mail:
ar@mm.unknown
Category : Research article
Models attempting to predict treeline shifts in changing climates must include the relevant ecological processes in sufficient detail. A previous correlative model study has pointed to nutrients, competition, and temperature as the most important factors shaping the treelines of Pinus sylvestris L., Picea abies (L.) H. Karst. and Betula pubescens Ehrh. in Finnish Lapland. Here, we applied a widely used process-based dynamic vegetation model (LPJ-GUESS) to (i) test its capability to simulate observed spatial and temporal patterns of the main tree species in Finnish Lapland, and (ii) to explore the model representation of important processes in order to guide further model development. A European parameterization of LPJ-GUESS overestimated especially P. abies biomass and the species’ northern range limit. We identified implemented processes to adjust (competition, disturbance) and crucial processes in boreal forests to include (nutrient limitation, forest management) which account for the model’s failure to (edaphically) restrict P. abies in Finnish Lapland and the resulting species imbalance. Key competitive mechanisms are shade and drought tolerance, nutrient limitation, fire resistance, and susceptibility to disturbances (storm, herbivory) which we discussed with respect to boreal ecology and promising model developments to provide a starting point for future model development.
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Schibalski,
Institute of Geoecology, Technische Universität Braunschweig, Langer Kamp 19c, D-38106 Braunschweig, Germany
E-mail:
a.schibalski@tu-braunschweig.de
- Lehtonen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: aleksi.lehtonen@luke.fi
- Hickler, Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, D-60325 Frankfurt am Main, Germany; Department of Physical Geography, Goethe University, Altenhöferallee 1, D-60438 Frankfurt am Main, Germany E-mail: thomas.hickler@senckenberg.de
- Schröder, Institute of Geoecology, Technische Universität Braunschweig, Langer Kamp 19c, D-38106 Braunschweig, Germany; Berlin-Brandenburg Institute of Advanced Biodiversity Research BBIB, Altensteinstr. 6, D-14195 Berlin, Germany E-mail: boris.schroeder@tu-bs.de
We designed a streamlined timber growth and quality model that aims at the effect of stand management on the efficiency of wood resource use. Applying the R based module toolbox to experimental plots of Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) we analysed essential model features for reflecting the influence of planting density on board strength. The current version realistically predicted a significant increase of centre board bending strength at tree age 40 with initial stand density. Model performance gained clear advantage from a) parameterisation of height to diameter allometry as dependent on planting density b) consideration of cambial age and cross‑sectional knot area in board strength computation. Crown shape was less decisive. The model produced a significant effect of planting density even after a whole rotation period of 70 years as well as a realistic spectrum of board bending strength.
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Poschenrieder,
Technische Universität München, Chair of Forest Growth and Yield Science, Hans Carl von Carlowitz Platz 2, 85354 Freising, Germany
http://orcid.org/0000-0002-9028-8583
E-mail:
Werner.Poschenrieder@lrz.tum.de
- Rais, Technische Universität München, Chair of Forest Growth and Yield Science, Hans Carl von Carlowitz Platz 2, 85354 Freising, Germany; Technische Universität München, Holzforschung München, Winzererstrasse 45, 80797 Munich, Germany E-mail: Andreas.Rais@hfm.tum.de
- van de Kuilen, Technische Universität München, Holzforschung München, Winzererstrasse 45, 80797 Munich, Germany E-mail: vandekuilen@hfm.tum.de
- Pretzsch, Technische Universität München, Chair of Forest Growth and Yield Science, Hans Carl von Carlowitz Platz 2, 85354 Freising, Germany E-mail: Hans.Pretzsch@lrz.tum.de
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Räty,
University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland
E-mail:
minna.s.raty@helsinki.fi
- Kangas, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland E-mail: ak@nn.fi
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Uusitalo,
The Finnish Forest Research Institute, Parkano unit, FI-39700 Parkano, Finland
E-mail:
jori.uusitalo@metla.fi
- Puustelli, University of Tampere, Department of Mathematics, Statistics and Philosophy, FI-33014 University of Tampere, Finland E-mail: ap@nn.fi
- Kivinen, University of Helsinki, Department of Forest Resource Management, Box 27, FI-00014 University of Helsinki, Finland E-mail: vpk@nn.fi
- Nummi, University of Tampere, Department of Mathematics, Statistics and Philosophy, FI-33014 University of Tampere, Finland E-mail: tn@nn.fi
- Sinha, Stat-Math Division, Indian Statistical Institute, 203 B.T. Road, Kolkata - 700 108, India E-mail: bks@nn.in
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Mehtätalo,
Yale School of Forestry and Environmental Studies, 205 Prospect Street, New Haven, CT 06511, USA
E-mail:
lauri.mehtatalo@metla.fi
- Maltamo, University of Joensuu, Faculty of Forestry, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: mm@nn.fi
- Kangas, University of Helsinki, Department of Forest Resources Management, P.O.Box 27, FI-00014 University of Helsinki, Finland E-mail: ak@nn.fi
