Issues

Forest cutting and natural reforestation essentially affect the species diversity, structure and live biomass of trees and green forest floor (GFF). Spruce forests, different-aged mixed deciduous-coniferous stands, and birch young forest in the taiga zone of northeastern Russia (Komi Republic) have been studied. Tree species are represented by Betula pendula, B. pubescens, Populus tremula, Pinus sylvestris, Picea obovata, Abies sibirica. Soil types at study objects are weakly peaty-weakly podzolic gley soil and illuvial-humus-iron podzol. Before cutting instead of todays deciduous forests there grew a 150-190-year-old spruce forest. GFF live biomass vary from 0.4 upto 3.9 t·ha-1 and reaches its highest values in spruce for-est and the lowest values in 37-year-old birch-aspen forest. High resistant of phytomass in spruce forest and 90-years-old birch-aspen forest, low resistant phytomass characterizes middle-aged deciduous-coniferous forests. Weight proportion grasses/mosses makes 1:1 in middle-aged deciduous-coniferous forests, 3:5 in birch young forest and 90-years-old birch-aspen forest, and 1:8 in spruce forest.

We studied the growth in height, diameter, volume and the most important wood proper-ties of 11-year old Ailanthus altissima (Mill.) Swingle trees grown at the Research station for fast-growing species near Svishtov, Bulgaria. We found that the height growth was most intensive during the first years with maximum rate in the 5th year. The diameter and volume growth were continuous and by the 11th year still had not reached a decrease in the rate. The wood density at air-dry condition (w=7.5 %) was 620 kg·m-3, at absolutely dry condition (w=0 %) was 580 kg·m-3, while at maximally saturated with water (density in row condition) it was 1045 kg·m-3. The volume shrinkage was 14.85 %. Head hardness, studied following Brinel method (in direction parallel to the grains), was 83.41 N·mm-2, the hardness in radial direction was 61.48 N·mm-2and in tangential direction - 52.03 N·mm-2. The bending strength (MOR) of air-dry wood was 71.11 N·mm-2. The modulus of elasticity (MOE) was 11.906 GPa. The compression strength parallel to the fibres was 55.83 N·mm-2. The shear strength parallel to the fibers in tangential plain was 14.41 N·mm-2, while in radial plain was 13.65 N·mm-2. Our results show that Ailanthus altissima is underestimated fast-growing species, whose wood can be successfully used for production of paper and furniture. Therefore we consider appropriate a recommendation to start trials with establishment of experimental plantation.

The aim of the study wais to make a comparative analysis of the growth rate of 54 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) provenances. The provenance test was established in the spring of 1990 with 3-year-old (3+0) seedlings planted in a 2x2 m plot design and two replications. The provenances originated from the North America and were separated into Coastal, Continental and Western Cascade groups. At age 20 growth rate was studied in terms of height and diameter, and stem volume. Coastal provenances demonstrated the best growth parameters, followed by Western Cascade Mountains and continental provenances. The provenances showing fastest growth provenances were Bremerton, of the coastal group, and Darrington, Newhalem and Idanha of the Western Cascade group. These provenances possessed also high resistance to fungal pathogens. Ten continental provenances had the lowest growth rate and productivity and were highly susceptible to the fungal pathogens Rhabdocline pseudotsugae and Phaeocryptopus gaumannii. Darrington from the Western Cascades in Washington is the recommended provenance for future afforestations with Douglas-fir in Bulgaria.

The main concern of a forester is to be able to collect and maintain accurate and detailed data in order to cope successfully with current needs but also to anticipate future situations. Generally speaking, the Cadastre is a tool for planning, rationalization and development of the country and environmental protection. The development of mountain areas consists of the development of anthropogenic influences, which – like every form of economic development – is usually accompanied by negative environmental impacts. Thus it is necessary to define the criteria considering Environmental Impact Assessment (EIA). The aim of this paper is to investigate and to clearly demonstrate the contribution of forest cadastre and EIA in Forest Management Planning. Forest cadastre, which is a special cadastre, should be in line with the technical specifications of the National one. The total cost is not just techno-economic, but also environmental, all of which constitutes the cost of the work. We must develop practical and objective methods in order to assess the environmental impacts in alternative solutions in order to determine the location that makes the work compatible with the natural environment. There can be no development and rational management of the forest without a forest cadastre. On the other hand, however, most of the country’s forests are degraded and of low productivity and most of them play a protective role. So the EIA is essential for the planning of any work.

The rapid development of technology and the broad use of computers during the recent years have resulted in new emerging opportunities across all technical domains. Thus, there have been developed the ambitious Digital Terrain Models (DTMs) to exploit these opportunities and leverage their capabilities for the common good. The DTMs provide the basis for developing a wide range of applications related to earth sciences. To be more specific, the former in Geoinformatics enable the possibilities of modelling, analysis and performance measurement of spatial phenomena related to topography or other technical areas with similar spatial properties. The DTMs can be used in conjunction with the Geographic Information Systems (GIS) in order to create a system which could be able to provide analytical data and information over terrain properties. In this essay a combination of DTMs with Geographical Information Systems (GIS) is undertaken, in an effort to create a hybrid out of these technologies. The initial thinking was to create a digital database that could provide comprehensive information over the number of fires, land areas and living species and finally the reaction time of the forest office commissions for the entire Greek state. What is more, a secondary objective was to monitor the efficiency degree of land exploitation by using DTMs in a targeted area. To a further extent, the combination of DTMs' information data such as vegetation, air temperature and wind direction, can contribute better in more efficient ways of forest fires prevention and suppression. In addition, the combination of the former along with the lands' efficient exploitation offers unlimited possibilities of spatial planning applications within the national digital cadastre. Subsequently, there are in our disposability unlimited scheduling capabilities to reduce arbitrary structure, violation of forest and other public territories, and an urban and regional environmentally friendly planning. To sum up, the DTMs assist us in a better and more rational development, protection and enhancement of mountainous areas.

Most of the ecosystems of our country are classified as degraded natural ecosystems, due to more or less human impact on the near or distant past. Many of these ecosystems are currently experiencing an evolutionary process, after their relief of adverse human activities, which mainly depends on the condition of the soil, the ecological diversity of the region and the rational and sustainable human management. The digital representation of the terrain, with software easy to handle, is a key task of the Geotechnical – Engineering Scientist. Furthermore, it is necessary for the upgrade of the existing environment that the current state of the ground (aspects, soil-cover) and the proposed one (roads, new soil-cover, micro-works) are depicted on three-dimensional intelligibly form. This process requires detailed surveying with geodesic station or GPS and automatic transfer into appropriate software for processing – a comparison of existing and proposed state, through several options. Consequently, the following problem is raised: farming and sustainable management of the forest without road openings is unrealistic, on the contrary most of our country's forests are degraded and with low productivity. Therefore, it is difficult to find the golden mean between the services of the needs of the forest exploitation and protection and the principle of the optimization that should apply in all economic-technical studies. The aim of this essay is to examine the contribution of the digital elevation model and generally, the high technology, to setting a framework for sustainable management and development, which will contribute to the recovery of degraded forests in Greece. The background on which the modern analysis and design of the site takes place, is a digital design in two-dimensional and three-dimensional forms. In relation to the above both the design and construction of forest roads ought to depend on digital technology. It is the largest infrastructure work in the mountainous area and contributes to the intensification of forest exploitation in economic growth and gradual improvement of degraded mountain areas.

Older methods and instruments were characterized by low accuracy or low productivity and high costs of fieldwork. From the 80s appeared on the market new types of instruments identified to measure accurately, productively, with a small amount of field work, but large cost of purchasing the instrument and modified analytical methods and efficiency. The era that we are living is characterized by evolutions of great importance in the sector of space applications. Especially, in the field of geodesy science, the applications of position determination with the use of satellite systems in global scale offered valuable solutions in chronic problems while creating new prospects but also greater demands. GPS and GLONASS are continually improving and the European Galileo and Chinese Compass systems are emerging to provide additional benefits for world-wide users. The main target of this research is the investigation of the possibilities of the triple frequency GPS at field work for forest map-ping. Previous works has been done by many researchers in all over the world. However, in this paper we concentrate on woodland area with receivers of two (2) frequencies (dual frequency) for both GPS and GLONASS satellites on. Also be able to receive signals from the third frequency GPS L5 and GALILEO, COMPASS satellites and the new L2C frequency for better and faster fixing in these environments. Finally are concluded proposals for the survey work in the forest cadastre, the forest opening up and the forest road construction, the study of temporal changes in the earth surface, for the measuring of forest data and for the civil engineer works.

The aim of this paper is to investigate the relationship between the surface hardness (Brinell's hardness) and colour change of thermally modified Sessile oak (Quercus sessiliflora Salisb.) wood. The material was taken from the coppice forests of the National Park Đerdap in eastern Serbia. Two groups of samples were selected from sapwood and from heartwood. The samples were heat treated at 170 °C, 190 °C and 210 °C for 4 hours. Radial hardness and CIELab (L*a*b*) coordinates of wood colour were investigated before and after the thermal treatment. The obtained results indicate that thermal treatment causes a reduction of CIElab coordinates and radial hardness whereas colour change (ΔE) increases with the rise in temperature. All the measured coordinates of the CIELab system have positive values in all the analyzed samples. The positive correlation between lightness (L*) and hardness was determined, whereas colour change has negative impact on radial hardness of oak wood. The results presented in this paper indicate that the colour can be used for assessment of hardness of thermally modified Sessile oak wood.

Designing the forest road network is a complex and specialized process including route selection, field investigation, data analyzing, and finally determining the best variant coping with the site-specific road locations. The present study was designated to evaluate the existing forest road network and to develop the existing forest road network in the mountainous forests, north of Iran (Savadkoh district). In order to find appropriate options for road routing, firstly the effective environmental factors were identified such as slope, aspect and elevation layers. In the next step, the Geographic Information System (GIS) was applied to evaluate and develop an existing forest road network. The length and density of the existing road network were about 1.75 km and 10.14 m·ha-1, respectively. The new variant was developed with regard to forest and physiographic conditions using PEGGER software. The length and density of new variant were 1.38 km and 8 m·ha-1, respectively. The development of the existing road network has been increased the total road density from 10.15 to 18.16 m·ha-1 and also could cover 55.5 % of the forest area for timber harvesting operations. Approximately, 32.14 % total length of the new variant was passed on 15-30 % slope and 64 % of the new variant was passed on 30-60 % slope terrains, which is more likely to be minimal negative environmental impact. Moreover, the new variant has had a better performance than the existing road. The results showed that this method can be more helpful and road network can be designed quickly with less cost than traditional method. Also, it was confirmed by computer analysis that application of this system at such level can be effective in preparation of the optimum routes designing plans.

The aim of the research was to elucidate existing intraspecific polymorphism of Douglas-fir plantations in Bulgaria and Belarus using Random Amplified Polymorphic DNA (RAPD) markers and to estimate genetic similarities and distances. RAPD-primers that reveal high polymorphism were selected. Seven Douglas-fir populations from Bulgaria and one from the Central Botanical Gardens in Belarus were included in the study, and individual RAPD pat-terns for 8 primers were obtained. The obtained RAPD-patterns were used to calculate the genetic distances among the populations studied.