Petrokas, R. 2010. Prerequisites for the Reproduction of Wild Cherry (Prunus avium L.).  Baltic Forestry 16 (1):139-153 (Review Paper)

Owing to its considerable capacity of seed dispersal and rapid propagation through adventitious sprouts from the root system, Wild cherry (Prunus avium L.) behaves as a colonizing species of initial succession stages and during progressing succession of the local disturbance it may become a component of climax or close-to-climax mesophilous forest ecosystems. A policy of non-management, especially following winter storms, may help maintain genetic diversity of Wild cherry through increased levels of both sexual and clonal recruitment. The aim of this review is an overview on the state of the knowledge about management influences on reproductive strategy of Wild cherry within the scope of its phenological behaviour. The vegetative and generative phenological behaviour of Wild cherry occurring as the result of ontogenetic variations in the traits of the trees and their parts could be monitored and described and the role of management (or environment) influences in determining this behaviour could be related. Some of the hypotheses, which are to be discussed in the research of Wild cherry reproduction, are presented in detail.

Key words: management influences, phenological behaviour, Prunus avium, reproduction

Huuhilo, T., Martikka, O., Butylina, S. and Kärki, T. 2010. Impact of Mineral Fillers to the Moisture Resistance of Wood-Plastic Composites.  Baltic Forestry 16 (1): 126-131

The impact of mineral fillers to the moisture resistance of the wood-plastic composites (WPC) is studied. Five inorganic fillers were tested for the wood-plastic composites calcium carbonate, two different types of wollastonite, soapstone and talc. The amount of polypropylene, wood and mineral was held constant, only the mineral type was changed during the tests. The studied composites were also compared with a reference sample, which was manufactured without any mineral addition. All added minerals decreased the swelling and moisture absorption of the wood-plastic composite considerably. Also the density of the wood-plastic composites increased when minerals were added. Without any added mineral, clear openings could be seen in the composite structure in scanning electron microscope (SEM) pictures. These openings could work as pathways for water into the inner parts of the WPC and increase swelling. It could also be seen in the SEM pictures that when mineral was added, these pathways for moisture were closed. After three weeks soak/freeze/dry cycles, the bending strength of the reference sample decreased considerably more than the bending strength of the samples with added minerals. Of the studied minerals, talc was the most effective.

Key words: wood-plastic composite, mineral, moisture resistance

Ozturk, T. and Senturk, N. 2010. Productivity and Time Studies of MB Trac 900 Tractor at Beech Stands on Mountainous Areas in Turkey.  Baltic Forestry 16 (1): 132-138

The purpose of this study is to investigate the productivity of the MB Trac 900 tractor during extraction of beech timber from stand of oriental beech in the North of Turkey. By using the methods of time study, the productivity of MB Trac 900 tractor was determined considering two different average skidding distances (i.e. short : 55 m and long: 105 m). The research results implied that some working characteristics of the MB Trac 900 tractor such as skidding distance, load volume, time consumption of handling operations and fuel consumption had an important impact on productivity of the tractor. Hourly productivity was computed as 14.580 m^³/hour for the average skidding distance of 55 m while it was 8.850 m^³/hour for the average skidding distance of 105 m. The cost of skidding was 3.5 $/m^³ and 9.6 $/m^³ for the specified average skidding distances, respectively. The average load volume for each cycle was found to be 1,490 m^³ and 2,130 m^³, respectively.

Key words: MB Trac 900, skidding, productivity, cost, time study

Grekin, M. and Verkasalo, E. 2010. Variations in Basic Density, Shrinkage and Shrinkage Anisotropy of Scots Pine Wood from Mature Mineral Soil Stands in Finland and Sweden.  Baltic Forestry 16 (1): 113-125.

Variations in basic density, radial and tangential shrinkage, and shrinkage anisotropy of wood in mature Scots pine trees growing on mineral soil stands were studied based on empirical materials from five geographical regions in Finland and Sweden. Cambium age explained better the pith-to-bark variation in basic density, as well as in tangential and radial shrinkage, than the distance from the pith. The model for radial density variation was evaluated on a cross-sectional scale; it explained approximately 50% of the density variation of the cross-sections. Based on the mixed model analysis with repeated measurements structure, approximately 52% of the variation in basic density on a cross-sectional scale was explained by the geographical origin and height position within a tree. By adding variables describing the trees and stands more precisely, approximately 64% of the total variation within trees and between trees, stands, and regions could be explained. In both cases, within-tree and between-tree random variation was statistically significant. The geographical origin affected significantly the variability in the studied properties; especially the within-tree variations decreased from the south to the north. On the other hand, the average level of radial and tangential shrinkage, as well as basic density, was the lowest in the north.

Key words: Pinus sylvestris, Scots pine, wood quality, basic density, shrinkage, linear mixed model, repeated measures