SURFACE IRREGULARITIES OF OAK WOOD AFTER TRANSVERSAL CUTTING WITH A CIRCULAR SAW

This paper deals with the effect of saw blade type (24, 40 and 60 teeth) and sawn distance on the primary profile (Pz) of tranvesre surface of European oak (Quercus robur L.) after transversal cutting. Transversal cutting was provided at constant cutting speed vc = 62 m.s-1and with manual feeding using circular saw blade. An additional parameter was to determine the maximum sawn distance for each type of saw blade up to the point where the saw blade overheated, as well as the beginning of the blackening of the wood surface. The highest values of the primary profile (Pz) were achieved with a saw blade with 24 teeth, lower values were measured on wood cut with a 40 tooth blade and the lowest values after cutting with a 60 tooth blade. As the saw distance increased, there was no rapid and steep increase in the primary profile values, but these values gradually increased slightly, probably due to the gradual blunting of the tool.

Corythucha arcuata (Say, 1832) (Hemiptera, Tingidae) in its invasive range in Europe: perception, knowledge and willingness to act in foresters and citizens

The oak lace bug (OLB) Corythucha arcuata (Say, 1832) is an invasive alien species (IAS) that potentially could have many negative impacts on European oak health. Certain measures can be applied to counteract these effects. However, these measures may not be acceptable for forest managers or other stakeholder groups, such as private forest owners, environmental NGOs or the general public. Thereby, we set out to study the perception and knowledge of foresters and other stakeholders on the health status of European oak forests affected by oak lace bug and to investigate what forest health management measures would be acceptable to these target groups. An online survey questionnaire was designed and distributed via social networks, as well as professional networks via e-mails. The survey questionnaire was completed by 2084 respondents from nine European countries: Austria, Croatia, Belgium, France, Hungary, Italy, Romania, Serbia and Slovenia. Even though only a little over 60% of respondents reported they had noticed the discolouration of oak leaves caused by OLB, almost all (93%) considered it to be a problem. As respondents come from a country where C. arcuata is widespread and established, people’s general knowledge and awareness of OLB began to increase. The survey revealed that foresters thought that the insect affected photosynthesis, acorn crop and the aesthetics of the trees, but cannot cause death of trees. However, they assume that the value of the wood would decrease (this fact is also supported by the respondents who are connected to an environmental NGO), but that OLB does not affect property value. However, forest owners claim that the value of the property can be affected and that people would avoid entering the forest. In terms of potential control methods, respondents preferred biological or mechanical measures over chemical ones. We consider this study to be a good basis for further research on the topic of perception, knowledge and attitudes related to OLB since we can expect that the IAS, such as OLB, will certainly spread to European countries that were not included in this survey.

Mineralization treatment of European oak heartwood with calcium oxalate for improved fire retardancy

Within the focus to apply substances for wood protections, here fire retardants, with low hazardous and low environmental impact is of interest. Additionally, European oak is an attractive species for various interior and exterior applications. However, oak is classified as very heavily treatable and thus impregnation is challenging. However, the focus of this study was to treat European oak with a new fire retardant based on an in-situ calcium oxalate deposition. Thin oak specimens with a thickness of 4 mm were investigated with two various formulations of aqueous salt solutions (potassium oxalate and calcium chloride, and potassium oxalate and calcium acetate) to obtain an in-situ mineralization of calcium oxalate during a two-step impregnation process. The uptake, the distribution, and the penetration of the salts for both applied formulations were investigated. Additionally, fire retardant properties were investigated in a single flame source test. It could be demonstrated that an acceptable degree of treatability was achieved for both applied formulations. The fire retardancy of the so mineralized material was clearly improved. Synergetic effects which might be caused by the reaction side products of the various formulations were found to be neglectable.

PECULIARITIES OF FORESTS AND FOREST USE ON THE TERRITORY OF SOE «TERNOPIL FORESTRY»

The analytical investigation of forests (age structure, age-class composition, forest categories) and forest use on the territory of SOE “Ternopil forestry” has been made. It has also been defined that within the activities of Ternopil forestry the differences in age structure of forest ranges, kinds of compositions and functional types of forests have been noticed. SOE “Ternopil forestry” is located in the central part of Ternopil oblast, which is characterized by a low level of forest cover: Zbarazh region – 9.1%, Pidvolochysk region – 5.1%, Terebovlia region – 8.4%, Ternopil region – 7.9%, Zboriv region – 11%. The area of SOE “Ternopil forestry” is 26015.0 ha; including territory covered with forests – 23913.2 ha (91.9%). The enterprise is also composed of 8 forest divisions such as Mykulyntsi, Skalat, Terebovlia, Ternopil, Mshanets, Zbarazh, Zaliztsi and Budaniv divisions. The fraction of area covered with forest vegetation on the territory of SOE “Ternopil forestry” is between about 91.3 % in Skalat forest division up to 96.1% in Ternopil forest division. The parts which are not covered with vegetation are represented by seed plots, artificial forests, open forests, burned areas, timber blockings, meadows, biomeadows, forest paths, glades and others. The forest plantations dominate in the structure of total area of the forest fund (57.3%); they occupy the area of 14606.0 ha and forest seed plots – 36.4%. The largest area in forestry is taken up by recreation forests (12.7 thousand ha). They have the largest part among the other forest categories (48.6%). The smallest part is taken up by the forests, which carry nature conservation, scientific and history and culture mission. Exploitable forests are represented on the territory of Budaniv forestry and occupy the area of 3142.9 ha. Besides that, we have to note that the part of forests in all divisions has special way of using and can be exploited. In the age structure of forests the major part is taken up by middle-aged plantations (64.6%). The largest part of the latest is in Mshanets division – 71.5% and Ternopil division – 67.4%. The biggest part of young plantations is in Zaliztsi division – 21.1% and Mykulyntsi division – 18.3%. They take the largest area in Terebovlia forestry (3668.3 ha). There is a sufficient part of recreation forests in the majority of forestry and its amount fluctuates between 83.8% up to 98.1%. The smallest part of recreation forests is in Budaniv (1.8%) and Zaliztsi (9.5%) divisions. The dominating type of landscape in recreational forests is closed type – 89.3% of the area, half open – 6.4% and open – 4.3%. The average age of forest plantations in SOE “Ternopil forestry” is 61 years. The oldest are European Beeches – 80 years, European Oak – 65 years, Scots pine – 56 years, English field maple – 60 years. The main forest forming species are hard wooden broadleaved species which make up 86.4%. They take up the largest part in Skalat (93.6%) and Mykulyntsi (94.4%) forest divisions. Among the broadleaved species the European Oak is dominating, and takes up the area of 13270.7 ha. More than 50% of the area where conifers grow are taken up by the Scots Pine. One of the ways of forest use on the SOE “Ternopil forstry” territory is stocking up wood from logging of the main use and also logging of formation and recreation. The renewable logging is done in all the forest categories. The annual amount of such logging comes to 2.3 thousand m3. Besides the logging of main use there others – formation and hygienic of forests, care logging (enlightening, selective cutting, thinning) sanitation and forest renewals. The main amount of wood is logged from the main use on the area of 66 ha and amounts to 20189 m3 It has been defined that the main ways of the forest use are logging and recreational forest use. Key words: forests, forest use, age structure, forest categories, recreational forests

Spatial and compositional structure of European oak urban forests in Kyiv city, Ukraine

Forest dimensional structure and tree species composition strictly define ecosystem resilience, success of its functioning and development. Spatial structure of forest compartments provides an additional information on the forest stand heterogeneity. The aim of this study is to examine structural patterns (both spatial and nonspatial ones) in European oak (Quercus robur L.) urban forests located in Kyiv city, Ukraine. We compared two middle-aged (~ 80 years) and two mature (~ 180 years) oak stands in terms of structural metrics collecting a data from geo-referenced trees on the established permanent sample plots. Younger stands reached similar tree diameter diversity (9.07 and 10.45 vs. 11.42 and 14.05 of Shannon indices), while the compositional diversity was driven by the dominance of either oak or European hornbeam (Carpinus betulus L.). We have not found any differences in the species mingling and deadwood distribution indices except a clear occurrence pattern for the stand located near roads. Herewith, the largest distance between the plot and park pathways was an indicator of changed spatial variation and tree dimensional differentiation within one middle-aged stand. We hypothesize that human impacts can alter structural development in urban deciduous forests providing both positive (gap formation, deadwood occurrence and ecosystem complexity) and negative (shifts in compositional and successional trajectories) effects on such forest stands.

Assessment of Stem Volume on Plots Using Terrestrial Laser Scanner: A Precision Forestry Application

Timber volume is an important asset, not only as an ecological component, but also as a key source of present and future revenues, which requires precise estimates. We used the Trimble TX8 survey-grade terrestrial laser scanner (TLS) to create a detailed 3D point cloud for extracting total tree height and diameter at breast height (1.3 m; DBH). We compared two different methods to accurately estimate total tree heights: the first method was based on a modified version of the local maxima algorithm for treetop detection, “HTTD”, and for the second method we used the centers of stem cross-sections at stump height (30 cm), “HTSP”. DBH was estimated by a computationally robust algebraic circle-fitting algorithm through hierarchical cluster analysis (HCA). This study aimed to assess the accuracy of these descriptors for evaluating total stem volume by comparing the results with the reference tree measurements. The difference between the estimated total stem volume from HTTD and measured stems was 2.732 m3 for European oak and 2.971 m3 for Norway spruce; differences between the estimated volume from HTSP and measured stems was 1.228 m3 and 2.006 m3 for European oak and Norway spruce, respectively. The coefficient of determination indicated a strong relationship between the measured and estimated total stem volumes from both height estimation methods with an R2 = 0.89 for HTTD and R2 = 0.87 for HTSP for European oak, and R2 = 0.98 for both HTTD and HTSP for Norway spruce. Our study has demonstrated the feasibility of finer-resolution remote sensing data for semi-automatic stem volumetric modeling of small-scale studies with high accuracy as a potential advancement in precision forestry.