Category :
Research article
article id 190,
category
Research article
Katri Luostarinen,
Veikko Möttönen.
(2009).
Effect of felling season, storage and drying on colour of silver birch (Betula pendula) wood from four different growing sites.
Silva Fennica
vol.
43
no.
4
article id 190.
https://doi.org/10.14214/sf.190
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Darkening of birch wood during artificial drying is a significant problem regarding the use of its timber as raw material by the mechanical wood industry. In the future, an increasing proportion of birch timber will be obtained from plantation forests, which differ from natural forests in many respects. In this investigation sample boards of Betula pendula, both from naturally regenerated stands and plantations, were sawn into the dimensions used as raw material for parquet billets. Growing site, felling season, and storage of logs were taken into account as possible factors affecting wood colour changes during drying. The wood of birches from fertile plantations remained lighter-coloured during conventional drying than the wood of naturally regenerated birches from low- and medium-fertile stands. The reason may be the difference in tree age and growth rate between natural and planted stands. Thus, it could be beneficial to grow birch in fertile stands so that the trees reach log size as young as possible. The results of this study emphasise the good quality of the birch wood from planted stands compared to natural stands with regard to its colour.
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Luostarinen,
Faculty of Forest Sciences, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland
E-mail:
katri.luostarinen@joensuu.fi
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Möttönen,
Department of Mechanical Engineering, Lappeenranta University of Technology, P.O. Box 20, FI-53851 Lappeenranta, Finland
E-mail:
vm@nn.fi
article id 189,
category
Research article
Lars Rytter,
Gunnar Jansson.
(2009).
Influence of pruning on wood characters in hybrid aspen.
Silva Fennica
vol.
43
no.
4
article id 189.
https://doi.org/10.14214/sf.189
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Fast-growing hybrid aspens (Populus tremula L. x P. tremuloides Michx.) are currently of great interest in Sweden since they can produce biomass at high rates and, at the same time, can be used to produce higher value wood products. This study focuses on the effects of pruning hybrid aspen to improve its wood quality. About 50% of the trees in the experimental stand were pruned by removing twigs, at heights up to 4 m, when they were 7–8 years old. Ten years later, 20 pruned and 20 unpruned trees, representing four clones, were randomly selected. Ten knots or twig/stem junctions, respectively, per tree were exposed for inspection using a chain saw and examined. The results revealed that pruned trees cicatrised the knots within about three years and thereafter produced substantial amounts of faultless wood. In contrast, unpruned trees (which had retained almost 80% of their twigs, often as dry twigs with bark pockets) had produced small uneven amounts of quality wood. Removal of twigs with acute angles and/or large diameters resulted in greater colour defects and rot in annual rings outside the pruning position, but the time of cicatrisation was not significantly affected. The results show that pruning can be used to enhance the wood quality of hybrid aspen over a short time period, and that pruning should be performed early during the rotation period when branches are small, in order to minimize discolouration and rot in the new annual rings.
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Rytter,
The Forestry Research Institute of Sweden (Skogforsk), Ekebo 2250, SE-26890 Svalöv
E-mail:
lars.rytter@skogforsk.se
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Jansson,
The Forestry Research Institute of Sweden (Skogforsk), Uppsala Science Park, SE-751 83 Uppsala
E-mail:
gj@nn.se
article id 188,
category
Research article
Mikko Havimo,
Juha Rikala,
Jari Sirviö,
Marketta Sipi.
(2009).
Tracheid cross-sectional dimensions in Scots pine (Pinus sylvestris) – distributions and comparison with Norway spruce (Picea abies).
Silva Fennica
vol.
43
no.
4
article id 188.
https://doi.org/10.14214/sf.188
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Cell wall thickness and tracheid radial and tangential diameter are important characteristics in papermaking. These fibre cross-sectional dimensions affect paper properties such as light scattering, and tear and tensile indexes. In the authors’ previous article, the mean values and distributions of tracheid cross-sectional dimensions were obtained for Norway spruce (Picea abies). This article characterises the cross-sectional tracheid properties of Scots pine (Pinus sylvestris) using exactly the same methodology as in the previous study on Norway spruce, which enables the comparison between the tree species. The distributions for Scots pine cell wall thickness and tracheid radial diameter were similar: a narrow peak due to earlywood tracheids, and a wide peak due to latewood tracheids. The tangential diameter distributions for Scots pine were very similar in both earlywood and latewood, having one wide peak. Also, the distributions in whole stem, top pulpwood and sawmill chip assortments were quite similar. The differences between Scots pine and Norway spruce tracheid cross-sectional dimensions were fairly marginal. This is at least the case when comparing large tracheid populations, in which differences tend to even out. The situation may be different on a more detailed level of observation, for example, when individual annual rings in the different tree species are compared.
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Havimo,
University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland
E-mail:
mikko.havimo@helsinki.fi
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Rikala,
University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland
E-mail:
jr@nn.fi
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Sirviö,
University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland
E-mail:
js@nn.fi
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Sipi,
University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland
E-mail:
ms@nn.fi
article id 187,
category
Research article
Tobias Biechele,
Leif Nutto,
Gero Becker.
(2009).
Growth strain in Eucalyptus nitens at different stages of development.
Silva Fennica
vol.
43
no.
4
article id 187.
https://doi.org/10.14214/sf.187
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Eucalypts are renowned for their high growth stress levels. These stresses cause splitting, warping and dimensional instability when cutting, processing and drying the wood. In Chile, large Eucalyptus nitens plantations can be found, which, due to these problems, are scarcely utilised for solid wood products (veneer, sawn wood). This study aims to determine the factors influencing growth stress at different stages of tree’s development, and to identify whether the factors influencing growth stress change over time. In five stands of different ages, growth strain, as an indicator of growth stress, was measured at different tree heights with the single hole drilling method. The tree variables DBH, tree height, slenderness (height/diameter ratio) and crown parameters also were measured. A correlation analysis of tree variables and growth strains was undertaken. The results obtained indicate a high variability in growth strain values. It was concluded that growth strain is not correlated with a single growth parameter, but with a combination of factors that variously influence it at different ages and tree heights.
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Biechele,
University of Freiburg, Institute of Forest Utilisation and Work Science, Werthmannstr. 6, DE-79085 Freiburg, Germany
E-mail:
tobias.biechele@fobawi.uni-freiburg.de
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Nutto,
University of Freiburg, Institute of Forest Utilisation and Work Science, Werthmannstr. 6, DE-79085 Freiburg, Germany
E-mail:
ln@nn.de
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Becker,
University of Freiburg, Institute of Forest Utilisation and Work Science, Werthmannstr. 6, DE-79085 Freiburg, Germany
E-mail:
gb@nn.de
article id 186,
category
Research article
Juho Rantala,
Pertti Harstela,
Veli-Matti Saarinen,
Leo Tervo.
(2009).
A techno-economic evaluation of Bracke and M-planter tree planting devices.
Silva Fennica
vol.
43
no.
4
article id 186.
https://doi.org/10.14214/sf.186
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Techno-economically reasonable mechanization of tree planting has proved to be a difficult task in the Nordic working conditions. Although planting machines and combinations of base machine and planting device have been developed since the 1970s, mechanized planting has not been cost-competitive to manual planting. The aim of this study was to find out work time distributions, productivities, costs and effects of different work difficulty factors on productivities and costs of the state-of-the-art Nordic planting devices, Swedish Bracke and Finnish M-Planter, and to compare the devices with each other. The theory of comparative time studies was the base for the experimental design of this study. In the average working conditions, productivity (E15) of M-Planter (236 seedlings/hour) was 36.0% higher than that of Bracke (174 seedlings/hour). Here, M-Planter performed planting work 23.4% cheaper than Bracke. However, the difference depended greatly on the working conditions; the more stones or stumps the smaller the difference, and the more slash the bigger the difference.
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Rantala,
Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland
E-mail:
juho.rantala@metla.fi
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Harstela,
Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland
E-mail:
ph@nn.fi
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Saarinen,
Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland
E-mail:
vms@nn.fi
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Tervo,
Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland
E-mail:
lt@nn.fi
article id 185,
category
Research article
Bianca N. I. Eskelson,
Tara M. Barrett,
Hailemariam Temesgen.
(2009).
Imputing mean annual change to estimate current forest attributes.
Silva Fennica
vol.
43
no.
4
article id 185.
https://doi.org/10.14214/sf.185
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When a temporal trend in forest conditions is present, standard estimates from paneled forest inventories can be biased. Thus methods that use more recent remote sensing data to improve estimates are desired. Paneled inventory data from national forests in Oregon and Washington, U.S.A., were used to explore three nearest neighbor imputation methods to estimate mean annual change of four forest attributes (basal area/ha, stems/ha, volume/ha, biomass/ha). The randomForest imputation method outperformed the other imputation approaches in terms of root mean square error. The imputed mean annual change was used to project all panels to a common point in time by multiplying the mean annual change with the length of the growth period between measurements and adding the change estimate to the previously observed measurements of the four forest attributes. The resulting estimates of the mean of the forest attributes at the current point in time outperformed the estimates obtained from the national standard estimator.
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Eskelson,
Oregon State University, Department of Forest Engineering, Resources and Management, 204 Peavy Hall, Corvallis, Oregon 97331, USA
E-mail:
bianca.eskelson@oregonstate.edu
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Barrett,
Oregon State University, Department of Forest Engineering, Resources and Management, 204 Peavy Hall, Corvallis, Oregon 97331, USA
E-mail:
tmb@nn.us
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Temesgen,
Oregon State University, Department of Forest Engineering, Resources and Management, 204 Peavy Hall, Corvallis, Oregon 97331, USA
E-mail:
ht@nn.us
article id 184,
category
Research article
Jaakko Repola.
(2009).
Biomass equations for Scots pine and Norway spruce in Finland.
Silva Fennica
vol.
43
no.
4
article id 184.
https://doi.org/10.14214/sf.184
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In this study, biomass equations for the above- and below-ground tree components of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies [L.] Karst.) were developed. The models were based on 908 pine trees and 613 spruce trees collected in 77 stands located on mineral soil, and represented a wide range of stand and site conditions in Finland. The whole data set consisted of three sub data sets: 33 temporary sample plots, five thinning experiments, and the control plots of 39 fertilization experiments. The biomass equations were estimated for the individual tree components: stem wood, stem bark, living and dead branches, needles, stump, and roots. In the data analysis, a multivariate procedure was applied in order to take into account the statistical dependence among the equations. Three multivariate models for above-ground biomass and one for below-ground biomass were constructed. The multivariate model (1) was mainly based on tree diameter and height, and additional commonly measured tree variables were used in the multivariate models (2) and (3). Despite the unbalanced data in terms of the response variables, the statistical method generated equations that enable more flexible application of the equations, and ensure better biomass additivity compared to the independently estimated equations. The equations provided logical biomass predictions for a number of tree components, and were comparable with other functions used in Finland and Sweden even though the study material was not an objective, representative sample of the tree stands in Finland.
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Repola,
Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland
E-mail:
jaakko.repola@metla.fi
article id 183,
category
Research article
Stella Bogino,
María José Fernández Nieto,
Felipe Bravo.
(2009).
Climate effect on radial growth of Pinus sylvestris at its southern and western distribution limits.
Silva Fennica
vol.
43
no.
4
article id 183.
https://doi.org/10.14214/sf.183
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The associations between tree-ring width and climatic variables, the tree age effect on climate-growth relationship and the drought index impact on radial growth of Scots pine (Pinus sylvestris L.) were studied in Mediterranean environments in the Iberian Peninsula. Dendrochronological techniques were applied to construct six tree-ring width chronologies for P. sylvestris. The association between tree growth and climate was analysed with correlation coefficients and bootstrapped response functions. Drought index (DRI) was used to detect the effects of aridity. Tree-ring width was positively correlated with rainfall in the growing season but this association stated earlier at the lowest altitudinal sites. The effects of temperature varied according to the site. The response to climatic variables depended on the age of the trees: more of the variability was explained by climatic variables in young stands than in old stands. The significant association between radial growth and DRI suggests that drought is a determining factor in the radial growth of P. sylvestris. Climate forecast scenarios show an increase in rainfall irregularity in the Mediterranean region so the differential tree response to rainfall at different elevations can be used to predict tree growth for determining silvicultural treatments.
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Bogino,
Universidad de Valladolid, Departamento de Producción Vegetal y Recursos Forestales, Joint Unit UVa-INIA ‘Sustainable Forest Management’, Avda. de Madrid 44, 34004 Palencia, Spain
E-mail:
sbogino@fices.unsl.edu.ar
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Fernández Nieto,
Universidad de Valladolid, Departamento de Producción Vegetal y Recursos Forestales, Joint Unit UVa-INIA ‘Sustainable Forest Management’, Avda. de Madrid 44, 34004 Palencia, Spain
E-mail:
mjfn@nn.es
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Bravo,
Universidad de Valladolid, Departamento de Producción Vegetal y Recursos Forestales, Joint Unit UVa-INIA ‘Sustainable Forest Management’, Avda. de Madrid 44, 34004 Palencia, Spain
E-mail:
fb@nn.es
article id 182,
category
Research article
Janne Miettinen,
Pekka Helle,
Ari Nikula,
Pekka Niemelä.
(2009).
Changes in landscape-scale habitat selection of capercaillie (Tetrao urogallus) in managed north-boreal forest.
Silva Fennica
vol.
43
no.
4
article id 182.
https://doi.org/10.14214/sf.182
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We studied changes in habitat selection of capercaillie in northern Finnish boreal forests at two spatial scales during two time periods, 1989–1992 and 2000–2003. We studied capercaillie densities and their changes between the study periods in relation to the landscape class proportions within 3-km buffer zones around the wildlife triangle center points. Furthermore, we compared the landscape class proportions in 800-meter buffer zones around capercaillie wildlife triangle count observations and around the counted wildlife triangle transects using t-tests and compositional analysis. At the local population scale (3 km) the change in adult density between the study periods was associated positively with the proportion of young thinning stands in 2003 and reversely with the mature stand (1992 and 2003) and clear-cut (1992) proportions. Capercaillie juvenile and pooled densities during 2000–2003 were positively associated with the advanced thinning stand proportion in 2003. At the capercaillie home range scale (800 m) habitats were rich in mature stands during 1989–1992 in relation to available habitats, but not during 2000–2003 when young thinning stands were more abundant in relation to available habitats. Relatively young managed forests can be suitable for capercaillie, but mature managed forests as capercaillie habitats may have deteriorated between the study periods. Spatial planning may help to form suitable areas that are large enough for the species, but the highest potential may lay in the forest stand scale, where increased cover on the ground could promote the habitat quality.
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Miettinen,
Kankurinhaka 14, FI-90450 Kempele, Finland
E-mail:
janne.miettinen@rktl.fi
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Helle,
Finnish Game and Fisheries Research Institute, Tutkijantie 2 E, FI-90570 Oulu, Finland
E-mail:
ph@nn.fi
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Nikula,
Finnish Forest Research Institute, Rovaniemi Research Unit, Eteläranta 55, FI-99600 Rovaniemi, Finland
E-mail:
an@nn.fi
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Niemelä,
University of Turku, Department of Biology, FI-20014 University of Turku, Finland
E-mail:
pn@nn.fi
article id 181,
category
Research article
Jari Miina,
Juha-Pekka Hotanen,
Kauko Salo.
(2009).
Modelling the abundance and temporal variation in the production of bilberry (Vaccinium myrtillus L.) in Finnish mineral soil forests.
Silva Fennica
vol.
43
no.
4
article id 181.
https://doi.org/10.14214/sf.181