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Silva Fennica vol. 44 no. 2 | 2010

Category: Research article

article id 456, category Research article
Sam B. Coggins, Nicholas C. Coops & Michael A. Wulder. (2010). Improvement of low level bark beetle damage estimates with adaptive cluster sampling. Silva Fennica vol. 44 no. 2 article id 456. https://doi.org/10.14214/sf.456
Detection of low level infestation in forest stands is of principle importance to determine effective control strategies before the attack spread to large areas. Of particular concern is the ongoing mountain pine beetle, Dendroctonus ponderosae (Hopkins) epidemic, which has caused approximately 14 million hectares of damage to lodgepole pine (Pinus contorta Dougl. ex. Loud var. latifolia Engl.) forests in western Canada. At the stand level attacked trees are often difficult to locate and can remain undetected until the infestation has become established beyond a small number of trees. As such, methods are required to detect and characterise low levels of attack prior to infestation expansion, to inform management, and to aid mitigation activities. In this paper, an adaptive cluster sampling approach was applied to very fine-scale (20 cm) digital aerial imagery to locate mountain pine beetle damaged trees at the leading edge of the current infestation. Results indicated a mean number of 7.36 infested trees per hectare with a variance of 18.34. In contrast a non-adaptive approach estimated the mean number of infested trees in the same area to be 61.56 infested trees per hectare with a variance of 41.43. Using a relative efficiency estimator the adaptive cluster sampling approach was found to be over two times more efficient when compared to the non-adaptive approach.
  • Coggins, Department of Forest Resources Management, University of British Columbia, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 ORCID ID:E-mail: scoggins@interchange.ubc.ca (email)
  • Coops, Department of Forest Resources Management, University of British Columbia, 2424 Main Mall, Vancouver, B.C., Canada V6T 1Z4 ORCID ID:E-mail:
  • Wulder, Canadian Forest Service (Pacific Forestry Centre), Natural Resources Canada, 506 West Burnside Rd., Victoria, B.C., Canada V8Z 1M5 ORCID ID:E-mail:
article id 455, category Research article
Seppo Kellomäki, Matti Maajärvi, Harri Strandman, Antti Kilpeläinen & Heli Peltola. (2010). Model computations on the climate change effects on snow cover, soil moisture and soil frost in the boreal conditions over Finland. Silva Fennica vol. 44 no. 2 article id 455. https://doi.org/10.14214/sf.455
This study considered how climate change affects the accumulation of snow, the soil moisture and soil frost at sites without tree cover in boreal conditions in Finland (60°–70°N). An increase of 4.5 °C in annual mean temperature and 20 % in annual precipitation were assumed for Finland by the year 2100 according to A2 emission scenario. Along with climate, the soil type of the permanent inventory plots of the Finnish National Forest Inventory was used. Soil and climate data were combined by using a process-based ecosystem model. Calculations were done for four periods: current climate (1971–2000), near future (2001–2020), mid-term future (2021–2050) and long-term future (2071–2100). According to our simulations, the average monthly duration and depth of snow decreased over the simulation period. However, the increasing precipitation may locally increase the snow depths in the mid-term calculations. In the autumn and winter, the average volumetric soil moisture content slightly increased in southern Finland during the near future, but decreased towards the end of the century, but still remained on a higher level than presently. In northern Finland, the soil moisture in the autumn and winter increased by the end of this century. In the summertime soil moisture decreased slightly regardless of the region. Throughout Finland, the length and the depth of soil frost decreased by the end of the century. In the south, the reduction in the depth was largest in the autumn and spring, while in the mid-winter it remained relatively deep in the middle of the century. In the north, the depth tended to increase during the first two calculation periods, in some areas, even during the third calculation period (2071–2100) due to reduced insulation effects of snow during cold spells. The wintertime increase in soil moisture and reduced soil frost may be reflected to reduced carrying capacity of soil for timber harvesting.
  • Kellomäki, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail: seppo.kellomaki@uef.fi (email)
  • Maajärvi, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Strandman, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Kilpeläinen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
  • Peltola, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland ORCID ID:E-mail:
article id 158, category Research article
Ville Hallikainen, Mikko Hyppönen, Leena Pernu & Jouni Puoskari. (2010). Family forest owners’ opinions about forest management in northern Finland. Silva Fennica vol. 44 no. 2 article id 158. https://doi.org/10.14214/sf.158
Forest management guidelines changed at the end of the 1990’s in Finland. Biodiversity, visual landscape, water systems, and different forms of forest use are now better taken into account. The objectives, outdoor recreation motives, and attitudes towards the present forest management activities of the non-industrial private forest owners called family forest owners in this article, whose forest holdings are located in northern Finland, were studied. In addition, a forest owner typology based on the above-mentioned motives, objectives, and attitudes was created, and the relationship between the typology and the forest owners’ background was tested. Principal component analysis, log-linear models, canonical correlations, and K-means cluster analysis were used in the data analysis. The results showed that especially commercial timber production, but also multiple-use forestry, is important for forest owners. Non-timber products such as game, berries, and forest mushrooms were considered more important than biodiversity, conservation of endangered species, tourism, and reindeer herding. The current, more ecological forest management activities were widely accepted by the owners. The changes had been perceived in the forest management activities. Close relationships were found between the objectives, attitudes and motives of the forest owners. Those owners who emphasized ecological tourism and multiple-use forestry, more frequently accepted detailed conservation and other “softer” management methods than those who emphasized commercial timber production. Typologies, called conservationists, timber producers, and multi-objective forest owners, were identified. Forest owner’s education and source of income were closely related to their typology. Highly educated forest owners and those who gained their money from tourism belonged to the groups named conservationists or multi-objective owners, whereas those who lived on forestry income represented timber producers.
  • Hallikainen, Finnish Forest Research Institute, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail: ville.hallikainen@metla.fi (email)
  • Hyppönen, Finnish Forest Research Institute, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Pernu, Finnish Forest Research Institute, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
  • Puoskari, Finnish Forest Research Institute, Eteläranta 55, FI-96301 Rovaniemi, Finland ORCID ID:E-mail:
article id 157, category Research article
Ville Kankaanhuhta, Timo Saksa & Heikki Smolander. (2010). The effect of quality management on forest regeneration activities in privately-owned forests in southern Finland. Silva Fennica vol. 44 no. 2 article id 157. https://doi.org/10.14214/sf.157
This study describes the effect of quality management on forest regeneration activities in privately-owned forests in southern Finland. The study material consists of two mail surveys conducted in 2006 and 2007. The questionnaires were sent to forestry professionals in Forest Owners’ Associations (FOAs), who had either participated (participants) or not (non-participants) in the forest regeneration quality management interventions in years 2000–2006. Quality management interventions of the FOAs included field inventories, feedback meetings, and education sessions about quality techniques. The activities of participant and non-participant FOAs were compared in terms of the available resources, the actions taken, and the aspirations for improvement. In the FOAs, which had participated in quality management, the number of excavator contractors had increased by 16% more than in the non-participant FOAs. The contractors had acquired 23% more soil preparation equipment under the supervision of the participant forestry professionals. The soil preparation method used in conjunction with Norway spruce that had most increased in use was patch mounding. Seedlings that were 1.5 years and older were used by participant forestry professionals in the planting of Norway spruce 11% more than by non-participants. The planting workers had attended 14% more educational sessions, while the use of self-control measurements in soil preparation and planting density had been adopted 10% more frequently under the supervision of the forestry professionals participating in the quality management. A greater interest in obtaining feedback by using quality control inventories was also found among forestry professionals who participated in quality management.
  • Kankaanhuhta, Finnish Forest Research Institute, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail: ville.kankaanhuhta@metla.fi (email)
  • Saksa, Finnish Forest Research Institute, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
  • Smolander, Finnish Forest Research Institute, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID:E-mail:
article id 156, category Research article
Ilkka Korpela, Hans Ole Ørka, Matti Maltamo, Timo Tokola & Juha Hyyppä. (2010). Tree species classification using airborne LiDAR – effects of stand and tree parameters, downsizing of training set, intensity normalization, and sensor type. Silva Fennica vol. 44 no. 2 article id 156. https://doi.org/10.14214/sf.156
Tree species identification constitutes a bottleneck in remote sensing-based forest inventory. In passive images the differentiating features overlap and bidirectional reflectance hampers analysis. Airborne LiDAR provides radiometric and geometric information. We examined the single-trees-level response of two LiDAR sensors in over 13 000 forest trees in southern Finland. We focused on the commercially important species. Our aims were to 1) explore the relevant LiDAR features and study their dependencies on stand and tree variables, 2) examine two sensors and their fusion, 3) quantify the gain from intensity normalizations, 4) examine the importance of the size of the training set, and 5) determine the effects of stand age and site fertility. A set of 570 semiurban broad-leaved trees and exotic conifers was analyzed to 6) examine the LiDAR signal in the economically less important species. An accuracy of 88 90% was achieved in the classification of Scots pine, Norway spruce, and birch, using intensity variables. Spruce and birch showed the highest levels of confusion. Downsizing the training set from 30% to 2.5% of all trees had only a marginal effect on the performance of classifiers. The intensity features were dependent on the absolute and relative sizes of trees, especially for birch. The results suggest that leaf size, orientation, and foliage density affect the intensity, which is thus not affected by reflectance only. Some of the ecologically important species in Finland may be separable, since they gave rise to high intensity values. Comparison of the sensors implies that performance of the intensity data for species classification varies between sensors for reasons that remained uncertain. Both range and gain receiver normalization improved species classification. Weighting of the intensity values improved the fusion of two LiDAR datasets.
  • Korpela, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail: ilkka.korpela@helsinki.fi (email)
  • Ørka, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, P.O.Box 5003, NO-1432 Ås, Norway ORCID ID:E-mail:
  • Maltamo, University of Eastern Finland, School of Forest Science, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Tokola, University of Eastern Finland, School of Forest Science, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail:
  • Hyyppä, Finnish Geodetic Institute, Department of Photogrammetry and Remote Sensing, P.O.Box 15, FI-02431 Masala, Finland ORCID ID:E-mail:
article id 155, category Research article
Minna Räty & Annika Kangas. (2010). Segmentation of model localization sub-areas by Getis statistics. Silva Fennica vol. 44 no. 2 article id 155. https://doi.org/10.14214/sf.155
Models for large areas (global models) are often biased in smaller sub-areas, even when the model is unbiased for the whole area. Localization of the global model removes the local bias, but the problem is to find homogenous sub-areas in which to localize the function. In this study, we used the eCognition Professional 4.0 (later versions called Definies Pro) segmentation process to segment the study area into homogeneous sub-areas with respect to residuals of the global model of the form height and/or local Getis statistics calculated for the residuals, i.e., Gi*-indices. The segmentation resulted in four different rasters: 1) residuals of the global model, 2) the local Gi*-index, and 3) residuals and the local Gi*-index weighted by the inverse of the variance, and 4) without weighting. The global model was then localized (re-fitted) for these sub-areas. The number of resulting sub-areas varied from 4 to 366. On average, the root mean squared errors (RMSEs) were 3.6% lower after localization than the global model RMSEs in sub-areas before localization. However, the localization actually increased the RMSE in some sub-areas, indicating the sub-area were not appropriate for local fitting. For 56% of the sub-areas, coordinates and distance from coastline were not statistically significant variables, in other words these areas were spatially homogenous. To compare the segmentations, we calculated an aggregate standard error of the RMSEs of the single sub-areas in the segmentation. The segmentations in which the local index was present had slightly lower standard errors than segmentations based on residuals.
  • Räty, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail: minna.s.raty@helsinki.fi (email)
  • Kangas, University of Helsinki, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
article id 154, category Research article
Henrik R. Hallingbäck, Gunnar Jansson, Björn Hannrup & Anders Fries. (2010). Which annual rings to assess grain angles in breeding of Scots pine for improved shape stability of sawn timber? Silva Fennica vol. 44 no. 2 article id 154. https://doi.org/10.14214/sf.154
The shape stability properties of sawn timber could be improved by breeding or grading Scots pine (Pinus sylvestris L.) for reduced grain angles. Currently, only grain angle assessments performed in single annual rings can be considered feasible in forest breeding programmes. The relevance of such methods in assessing shape stability traits was evaluated by taking grain angle measurements beneath the bark in a 36-year-old Scots pine progeny trial. Several grain angle measurements from stem discs were also taken from a sample of 162 trees. Phenotypic correlations were estimated between grain angle and the bow, crook and twist developed in 316 sawn and dried boards. All single annual ring assessments, including measurements taken directly under the bark, were significantly correlated with twist. The highest correlations (0.60–0.70) were observed in annual rings numbered 8–20 and at distances of 30–70 mm from the pith, indicating those parts of logs where grain angles have the largest impact on twist. These results suggests, that grain angles measured beneath the bark are relevant to the twist of sawn small timber, and that any single annual ring could be chosen for the assessment, provided that the tree diameter is within the 60–140 mm range. No appreciable correlations were observed between grain angles and either crook or bow.
  • Hallingbäck, Dept of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden ORCID ID:E-mail: henrik.hallingback@vbsg.slu.se (email)
  • Jansson, The Forestry Research Institute of Sweden, Uppsala, Sweden ORCID ID:E-mail:
  • Hannrup, The Forestry Research Institute of Sweden, Uppsala, Sweden ORCID ID:E-mail:
  • Fries, Dept of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden ORCID ID:E-mail:
article id 153, category Research article
Dirk Bieker & Steffen Rust. (2010). Non-destructive estimation of sapwood and heartwood width in Scots pine (Pinus sylvestris L.). Silva Fennica vol. 44 no. 2 article id 153. https://doi.org/10.14214/sf.153
Accurate estimates of the water conducting sapwood area are necessary to scale sapflow measurements to tree and stand level transpiration. We tested a non-destructive method, electric resistivity tomography (ERT), to estimate the area of conductive sapwood in 9 Pinus sylvestris L. trees in lower Saxony, Germany. Tomograms were compared to cross-sections stained with benzidine after harvesting. All tomograms displayed a distinct pattern of low resistivity at the stem perimeter and high resistivity in the stem centre with a steep increase in resistivity in between, assumed to indicate the transition from sapwood to heartwood. The tomograms showed a sapwood width 2 cm smaller than the staining method. This indicates that staining methods overestimate the amount of active sapwood because when heartwood is formed, moisture content decreases before extractive contents reach levels visible by staining. The ERT method is a new powerful method for the non-destructive estimation of sapwood and heartwood width.
  • Bieker, University of Applied Sciences and Arts, Faculty of Resource Management, Büsgenweg 1a, D-37077 Göttingen, Germany ORCID ID:E-mail:
  • Rust, University of Applied Sciences and Arts, Faculty of Resource Management, Büsgenweg 1a, D-37077 Göttingen, Germany ORCID ID:E-mail: rust@hawk-hhg.de (email)
article id 152, category Research article
Torgny Persson, Bengt Andersson & Tore Ericsson. (2010). Relationship between autumn cold hardiness and field performance in northern Pinus sylvestris. Silva Fennica vol. 44 no. 2 article id 152. https://doi.org/10.14214/sf.152
Results from 3 artificial freezing tests (one-year-old seedlings) and 15 field trials (9- to 21-year old trees) of half-sib offspring from first generation Scots pine (Pinus sylvestris L.) plus-trees were used to estimate the amount of additive genetic variance for autumn cold hardiness and traits assessed in the field, and the genetic correlations between them. Cold hardiness of individual seedlings was scored visually, based on the discoloration of their needles after freezing in a climate chamber. The field traits analyzed were tree vitality, tree height, spike knot frequency, branch diameter, branch angle, stem straightness, and susceptibility to infection by the pathogenic fungi Phacidium infestans L., Gremmeniella abietina (Lagerb.) Morelet, Melampsora pinitorqua (Braun) Rostr. and Lophodermella sulcigena (Rostr.) Höhn. Narrow sense individual heritabilities varied between 0.30 and 0.54 for autumn cold hardiness, 0 and 0.18 for tree vitality, 0.07 and 0.41 for tree height, and 0.01 and 0.26 for the remaining traits. Based on the results of the artificial freeze tests, our estimates of additive genetic correlations indicate that while early selection for cold hardiness can improve seedling survival rates in the field, it may also reduce growth in mild environments. It also has minor effects on quality traits and attack by common fungal diseases. The results indicate that artificial freeze testing is an appropriate method for identifying suitable clones for establishing seed orchards to supply stock for the reforestation of regions with harsh environments.
  • Persson, Forestry Research Institute of Sweden, Sävar, Sweden ORCID ID:E-mail: torgny.persson@skogforsk.se (email)
  • Andersson, Forestry Research Institute of Sweden, Sävar, Sweden ORCID ID:E-mail:
  • Ericsson, Forestry Research Institute of Sweden, Sävar, Sweden ORCID ID:E-mail:
article id 151, category Research article
Janne Miettinen, Pekka Helle, Ari Nikula & Pekka Niemelä. (2010). Capercaillie (Tetrao urogallus) habitat characteristics in north-boreal Finland. Silva Fennica vol. 44 no. 2 article id 151. https://doi.org/10.14214/sf.151
This study aimed to identify tools for taking capercaillie habitats into consideration in forest management. This would provide new alternatives for ecologically more sustainable forest management. Capercaillie summer and winter locations, from wildlife monitoring counts (1998–2004) in northern Finland, and reference, non-capercaillie locations were combined with forest planning data, and the area proportions of different landscape classes in an 800-m radius circle surrounding capercaillie and reference locations were compared. Thinning stands (in summer and winter) and spruce mires (in summer) were more abundant in capercaillie habitats than in reference landscapes, whereas e.g. seedling stands, mature stands and waste land areas were less abundant. The relative habitat use was highest in mean tree diameter (DBH) classes from 10.5 to 14.5 cm in summer habitats of adult capercaillie in heath forests, whereas in peatland forests, in brood habitats and in winter habitats it peaked in diameter classes 14.5 to 18.5 cm. The tree layer density was positively associated with the relative habitat use. A trend of lower habitat use was detected in the largest diameters (17–40 cm) in comparison to middle-sized diameters (10–16 cm) in heath forests, but not in peatland forests. Relatively young managed forests (age 30–40 years or more) can form suitable capercaillie habitats in north-boreal forests. However, this suitability is not necessarily permanent. Understorey management, longer rotations and multicohort forest management are suitable tools for capercaillie habitat management, because they can increase the available cover close to the ground, canopy cover, overall forest cover at the landscape scale and bilberry cover.
  • Miettinen, Finnish Game and Fisheries Research Institute, Finland ORCID ID:E-mail: janne.miettinen@rktl.fi (email)
  • Helle, Finnish Game and Fisheries Research Institute, Finland ORCID ID:E-mail:
  • Nikula, Finnish Forest Research Institute, Finland ORCID ID:E-mail:
  • Niemelä, University of Turku, Dept of Biology ORCID ID:E-mail:
article id 150, category Research article
Sini Eräjää, Panu Halme, Janne S. Kotiaho, Anni Markkanen & Tero Toivanen. (2010). The volume and composition of dead wood on traditional and forest fuel harvested clear-cuts. Silva Fennica vol. 44 no. 2 article id 150. https://doi.org/10.14214/sf.150
Logging residue and cut stumps are increasingly used as a renewable energy source known as forest fuel. Forest fuel harvesting obviously reduces the volume of dead wood and is likely to alter the dead wood composition, but the magnitude of the change is not known. Such information is important for the evaluation of the effects of forest fuel harvesting on biodiversity because a large proportion of forest dwelling species are directly dependent on dead wood. We measured the volume and characteristics of all dead wood units with a minimum diameter of 2 cm and a minimum length of 20 cm on 10 forest-fuel harvested and 10 traditional (control) clear-cuts. The total volume of dead wood at forest fuel harvested and control clear-cuts was 26.0 and 42.3 m3/ha, respectively. The volumes were much greater than expected suggesting that the volume of dead wood on clear-cuts has been underestimated in previous studies. Forest fuel harvested clear-cuts had 42% less branches and 81% less cut stumps than control clear-cuts but there were no differences in the volume of logs and pieces of logs, snags or roots. The volume of fine woody debris was negatively affected by forest fuel harvesting. We conclude that fine woody debris and cut stumps form a considerable resource on clear-cuts that is reduced by forest fuel harvesting. These components of dead wood have potential to be of importance in managed forests and thus deserve more attention in future biodiversity studies.
  • Eräjää, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland ORCID ID:E-mail:
  • Halme, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland ORCID ID:E-mail: panu.halme@jyu.fi (email)
  • Kotiaho, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland ORCID ID:E-mail:
  • Markkanen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland ORCID ID:E-mail:
  • Toivanen, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland ORCID ID:E-mail:
article id 149, category Research article
Juha Kaitera & Heikki Nuorteva. (2010). Effects of Melampyrum extracts on the growth of axenic cultures of Cronartium flaccidum and Peridermium pini. Silva Fennica vol. 44 no. 2 article id 149. https://doi.org/10.14214/sf.149
For 3–6 months, mycelial colonies cultured from 5 isolates of each of two pine stem rusts (Cronartium flaccidum and Peridermium pini) were grown on nutrient-rich agar supplemented with Melampyrum extracts. Non-autoclaved extracts of M. pratense significantly reduced the growth of P. pini. The growth of C. flaccidum isolates was slightly stimulated after the second month of incubation but after that was inhibited during incubation months 4–6. We observed considerable variation in colony growth, a significant component of which was explained by incubation time, isolate, growth medium and their interaction. Rust species (C. flaccidum or P. pini) was not an important factor in growth variation. While sterilized extracts of M. pratense, M. sylvaticum and M. nemorosum did not significantly affect growth, colonies of C. flaccidum were slightly stimulated, whereas colonies of P. pini were slightly inhibited. Generally, isolates of P. pini grew better and showed a slower rate of degeneration than C. flaccidum on all media.
  • Kaitera, Finnish Forest Research Institute, Northern Finland Regional Unit, FI-91500 Muhos, Finland ORCID ID:E-mail: juha.kaitera@metla.fi (email)
  • Nuorteva, Finnish Forest Research Institute, Southern Finland Regional Unit, FI-01301 Vantaa, Finland ORCID ID:E-mail:

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