Category :
Research article
article id 476,
category
Research article
Ignazio Monteleone,
Diana Ferrazzini,
Piero Belletti.
(2006).
Effectiveness of neutral RAPD markers to detect genetic divergence between the subspecies uncinata and mugo of Pinus mugo Turra.
Silva Fennica
vol.
40
no.
3
article id 476.
https://doi.org/10.14214/sf.476
Abstract |
View details
|
Full text in PDF |
Author Info
Fifteen populations of Pinus mugo subsp. mugo (shrub) and Pinus mugo subsp. uncinata (erect), located in the Alps, were investigated through genetic variation scored at 64 polymorphic RAPD loci. In addition, morphological traits of the female cones were analysed. According to AMOVA most of the genetic variation was found within populations (83.39%), and only 1.25% of it between subspecies. Populations differed in terms of their internal genetic variation, with Nei’s gene diversity ranging from 0.227 to 0.397. Morphological data showed differences between subspecies, although none of the populations showed full accordance with expectations. Significant correlation was found between matrices for geographical and morphological distances, while genetic distances were not correlated with any other aspect. The efficacy of morphological and RAPD markers in discriminating between subspecies, and the contribution of the results in relation to the preservation of biodiversity, are discussed.
-
Monteleone,
DI.VA.P.R.A., Plant Genetics and Breeding, University of Turin, via Leonardo da Vinci 44, I-10095 Grugliasco, Italy
E-mail:
im@nn.it
-
Ferrazzini,
DI.VA.P.R.A., Plant Genetics and Breeding, University of Turin, via Leonardo da Vinci 44, I-10095 Grugliasco, Italy
E-mail:
df@nn.it
-
Belletti,
DI.VA.P.R.A., Plant Genetics and Breeding, University of Turin, via Leonardo da Vinci 44, I-10095 Grugliasco, Italy
E-mail:
piero.belletti@unito.it
article id 336,
category
Research article
Ann Hedlund.
(2006).
The attractiveness of the work is affected when production of handcrafted log houses moves indoors.
Silva Fennica
vol.
40
no.
3
article id 336.
https://doi.org/10.14214/sf.336
Abstract |
View details
|
Full text in PDF |
Author Info
Viewed from a historical perspective, a shift has occurred within the forestry and wood sector towards indoor work. In Sweden, the production of handcrafted log houses has now also begun to move indoors. With a point of departure in development processes within the log house sector involving working indoors, education, work attractiveness, between 2001–2005, the aim of this study was to compare indoor work with outdoor work, based on log house builders’ experience of working on handcrafted log houses. Methods used in the interactive development project involving apprentices, experienced log house builders and researchers, were participation with continuous documentation of experiences and opinions; questions; interviews; and measurement of the work environment. The Attractive Work Model has been used in order to analyse perceptions and values. The changes, 15 out of 22 areas, were perceived both negatively and positively. Therefore, it can not be said that working on traditional, handcrafted log houses becomes more attractive if it is moved indoors. The majority wanted to work both outdoors and indoors, while most of the others only wanted to work outdoors. The results indicate that there is scope for developing more attractive work indoors by utilising experiences from log house builders and closely related activities such as the forestry and wood sector. Changes made within one area of work attractiveness affect other areas. Further research is needed both with regard to comparisons between indoor and outdoor work and regarding the interaction between the areas that are identified in the Attractive Work Model.
-
Hedlund,
Dalarna University, SE-781 88 Borlänge, Sweden
E-mail:
ahd@du.se
article id 335,
category
Research article
Markus Holopainen,
Mervi Talvitie.
(2006).
Effect of data acquisition accuracy on timing of stand harvests and expected net present value.
Silva Fennica
vol.
40
no.
3
article id 335.
https://doi.org/10.14214/sf.335
Abstract |
View details
|
Full text in PDF |
Author Info
Modern remote sensing provides cost-efficient spatial digital data that are more accurate than before. However, the influence of increased accuracy and cost-efficiency on simulations of forest management planning has not been evaluated. The aim of the present study was to analyse the effect of data acquisition accuracy on standwise forest inventory by comparing the accuracy and cost of traditional compartmentwise inventory methods with 2D and 3D measurements of digital aerial photographs and airborne laser scanning. Comparison was based on the expected net present value (NPV), i.e. economic losses that consisted of the inventory costs and incorrect timings of treatments. The reference data, totalling 700 ha, were measured from Central Park in the city of Helsinki, Finland. The data were simulated to final cut with a MOTTI simulator, which is a stand-level analysis tool that can be used to assess the effects of alternative forest management practices on growth and timber yield. The results showed that when inventory costs were not considered there were no significant differences between the expected NPV losses in 3D measurements of digital aerial photographs, laser scanning and the compartmentwise method. When inventory costs were taken into account, the compartmentwise method was still the most efficient inventory method in the study area. Forest inventories, however, are usually directed to larger areas when the costs per hectare of remote-sensing methods decrease. As a result of better accuracies, 3D and compartmentwise methods always produce better results than the 2D method when NPV losses are accounted. Simulations of this type are based on the accuracies and costs of the 3D data available today, assuming that the data can be used in tree-level measurements.
-
Holopainen,
University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland
E-mail:
markus.holopainen@helsinki.fi
-
Talvitie,
University of Helsinki, Department of Forest Resource Management, P.O. Box 27, FI-00014 University of Helsinki, Finland
E-mail:
mt@nn.fi
article id 334,
category
Research article
Jouni Siipilehto.
(2006).
Linear prediction application for modelling the relationships between a large number of stand characteristics of Norway spruce stands.
Silva Fennica
vol.
40
no.
3
article id 334.
https://doi.org/10.14214/sf.334
Abstract |
View details
|
Full text in PDF |
Author Info
The aim was to produce models for a large number of stand characteristics of Norway spruce dominated stands. A total of 227 national forest inventory based permanent stand plots, dominated by Norway spruce (Picea abies), were used in modelling eight stand variables as a function of the stand mean biological age and site characteristics. The basic models were able to characterize the average development of the modelled stand variables, but resulted in a relatively high RMSE. Basal area (G) and stem number (N) were the most inaccurate, having a RMSE of 34–41%, while that of mean diameter and height characteristics varied between 16–20%. The expectations and error variances of the basic models were calibrated with known stand variables using linear prediction theory. The best linear unbiased predictor (BLUP) with a single stand variable used for calibration proved to be ineffective for unknown G and N, but relatively effective for the unknown mean characteristics. However, calibration with one sum and one mean characteristic proved to be effective, and additional calibration variables enhanced the precision only marginally. The BLUP method provided a flexible approach when characterizing the relationships between a large number of stand variables, thus enabling multiple use of these models because they were not fixed to a specific inventory system.
-
Siipilehto,
Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland
E-mail:
jouni.siipilehto@metla.fi
article id 333,
category
Research article
Lauri Mehtätalo,
Matti Maltamo,
Annika Kangas.
(2006).
The use of quantile trees in the prediction of the diameter distribution of a stand.
Silva Fennica
vol.
40
no.
3
article id 333.
https://doi.org/10.14214/sf.333
Abstract |
View details
|
Full text in PDF |
Author Info
This study deals with the prediction of the basal area diameter distribution of a stand without using a complete sample of diameters from the target stand. Traditionally, this problem has been solved by either the parameter recovery method or the parameter prediction method. This study uses the parameter prediction method and the percentile based diameter distribution with a recent development that makes it possible to improve these predictions by using sample order statistics. A sample order statistic is a tree whose diameter and rank at the plot are known, and is referred to in this paper as a quantile tree. This study tested 13 different strategies for selection of the quantile trees from among the trees of horizontal point sample plots, and compared them with respect to RMSE and the bias of four criterion variables in a dataset of 512 stands. The sample minimum was found to be the most promising alternative with respect to RMSE, even though it introduced a rather large amount of bias in the criterion variables. Other good and less biased alternatives are the second and third smallest trees and the tree closest to the plot centre. The use of minimum is recommended for practical inventories because its rank is probably easiest to determine correctly in the field.
-
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
article id 332,
category
Research article
Marc Palahí,
Timo Pukkala,
Antoni Trasobares.
(2006).
Calibrating predicted tree diameter distributions in Catalonia, Spain.
Silva Fennica
vol.
40
no.
3
article id 332.
https://doi.org/10.14214/sf.332
Abstract |
View details
|
Full text in PDF |
Author Info
Several probability density functions have been used in describing the diameter distributions of forest stands. In a case where both the stand basal area and number of stems per hectare are assessed, the fitted or predicted distribution is scaled using only one of these variables, with the result that the distribution often gives incorrect values for the other variable. Using a distribution that provides incorrect values for known characteristics means wasting information. Calibrating the distribution so that it is compatible with the additional information on stand characteristics is a way to avoid such wasting. This study examined the effect of calibration on the accuracy of the predicted diameter distributions of the main tree species of Catalonia. The distributions were calibrated with and without considering the prediction errors of the frequencies of diameter classes. When prediction errors were assumed, the calibration was done with and without making allowance for estimation errors in the stand level calibration variables. Calibrated distributions were more accurate than non-calibrated in terms of sums of different powers of diameters. The set of calibration variables that gave the most accurate results included six stand variables: number of trees per hectare, stand basal area, basal-area-weighted mean diameter, non-weighted mean diameter, median diameter, and basal area median diameter. Of the tested three-variable combinations the best was: number of trees per hectare, stand basal area, and basal-area-weighted mean diameter. Means were more useful calibration variables than medians.
-
Palahí,
Centre Tecnológic Forestal de Catalunya. Passeig Lluis Companys, 23, 08010, Barcelona, Spain
E-mail:
marc.palahi@ctfc.es
-
Pukkala,
University of Joensuu, Faculty of Forestry, P.O. Box 111, 80101 Joensuu, Finland
E-mail:
tp@nn.fi
-
Trasobares,
Foreco Technologies, Av. Diagonal 416, Estudio 2, Barcelona 08037, Spain
E-mail:
at@nn.es
article id 331,
category
Research article
Jouni Siipilehto.
(2006).
Height distributions of Scots pine sapling stands affected by retained tree and edge stand competition.
Silva Fennica
vol.
40
no.
3
article id 331.
https://doi.org/10.14214/sf.331
Abstract |
View details
|
Full text in PDF |
Author Info
The paper focused on the height structure of Scots pine saplings affected by (1) retained solitary pine trees or (2) a pine-dominated edge stand. The study material in (1) and (2) consisted of ten separate regeneration areas in southern Finland. In (1) 2-m radius study plots were located at 1, 3, 6 and 10 m distances from 10 systematically selected, solitary retained trees in each stand. In (2) the study plots were systematically located within 20 m from the edge stand. Competition of the individual trees was modelled using ecological field theory. The 24th and 93rd sample percentiles were used for estimating the height distribution using the two-parameter Weibull function. The models incorporated the effect of varying advanced tree competition on the predicted percentiles. Competition free dominant height was used as a driving variable for the developmental phase. Competition resulted in retarded height development within a radius of about 6 m from the retained tree, while it extended up to roughly half of the dominant height of the edge stand. The height distribution without external competition was relatively symmetrical, but increasing competition resulted in a more peaked and skewed distribution. Slight differences were found between northern sunny and southern shaded stand edges, while the least retarded height occurred at the north-western edge receiving morning sunlight. Kolmogorov-Smirnov goodness-of-fit tests showed acceptable and equal fit for both data sets; 2% and 8% of the distributions did not pass the test at the alpha 0.1 level when the Weibull distribution was estimated with the observed or predicted percentiles, respectively.
-
Siipilehto,
Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland
E-mail:
jouni.siipilehto@metla.fi
article id 330,
category
Research article
Benoit Lapointe,
Robert Bradley,
William Parsons,
Suzanne Brais.
(2006).
Nutrient and light availability to white spruce seedlings in partial and clearcut harvested aspen stands.
Silva Fennica
vol.
40
no.
3
article id 330.
https://doi.org/10.14214/sf.330