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Sympozja Formec obejmujące tematykę rozwoju nowych technologii w leśnictwie zostały zapoczątkowane w Zwoleniu (ówczesnej Czechosłowacji) w 1966 roku. Spotkania zostały zainicjowane potrzebą wymiany informacji pomiędzy naukowcami z podzielonej wówczas Europy na blok zachodni i wschodni. Obecnie Formec stanowi główną platformę wymiany wiedzy i doświadczenia pomiędzy naukowcami i praktykami. Nowości z zakresu mechanizacji prac leśnych zostały omówione podczas dorocznego sympozjum w 2011 roku, w Graz, Austria. Tematem wiodącym była problematyka pozyskiwania drewna w warunkach górskich. Jednocześnie szeroko omawianym wątkiem była bioenergia pochodząca z surowca drzewnego. Odbywające się w tym samym czasie targi leśne Austrofoma pozwalały na skonfrontowanie rozważań konferencyjnych z pozyskiwaniem drewna w lesie, zarówno okrągłego, jak i rozdrobnionego.
The delimbing and bucking of timber using a harvester head is very productive in comparison with a chainsaw operations, however it can cause damage to the outer layer of round wood. This damage can originate from the delimbing knives or from the feed roller spikes. As a consequence, grey fungi can develop on coniferous species, and faster wood drying is also observed (with no regard to the species). Feed roller spikes create cuts and dents on the outer layers of the wood. When plywood is processed, the cuts and dents are recognised as damage as a consequence, they lower the wood quality and value. The objective of the presented research was to find out: 1) the depth of cuts, 2) the potential loss of volume, and 3) product value loss due to damage to plywood caused by feed roller spikes. The research was carried out on alder (Alnus glutinosa Geartn.) plywood logs harvested by a Valmet 911.4 with a 360.2 head. Measurements were taken using an electronic calliper with an accuracy of 0.01 mm. 16 plywood logs were considered, on which 384 measurement points (depth of spike cuts) were selected on different areas along the length of the log: 1, 2, 3 and 4 m from the butt end. The maximum depth of the spike cut was observed on the bottom part of the logs (1 m from the butt end) and amounted to 3.9 mm. This damage depth was statistically different to those at the 2nd, 3rd and 4th metre points, amounting to 1.9, 1.9 and 2.1 mm, respectively. The biggest volume losses were on the 1st metre of the plywood assortments: 0.004 m³ (4% of the volume), while on the further parts (2nd, 3rd and 4th metres) only 0.002 m³ of the plywood had damage (2% of the volume). In addition, the highest product value loss was on the butt end logs and amounted to 302 PLN/€72 per 100 m³. The following plywood assortments (2 nd , 3th and 4 th metres) had a loss of 76 PLN/€18 per 100 m³. Therefore, when plywood assortments are processed using a Valmet 911.4 harvester with a 360.2 head, it is recommended that after cutting and felling a tree, the plywood section of the alder tree trunk is cut off without feeding it through the harvester head.
A new HSM 904Z 6WD skidder of a large size was tested in a 140-year-old beech stand in northern Poland. The aim of the study was to analyse machine productivity and impact on the soil (bulk density and cone penetrometer test) and the remaining natural regeneration caused by skidding. Trees were cut by chainsaw and, if possible, felled into the direction of the skidroads. After delimbing, logs with a top diameter of a minimum 7 cm over the bark were prepared. The average skidding operational productivity including piling was 21.0 m3x h-1. At the same time, the level of damage in natural regeneration was: 18% (38% due to both: felling and skidding). An analysis of the soil after skidding showed that the density had grown by 15-30 gx cm-3. Increase of penetration resistance was up to 2.77 MPa as the biggest.
In recent years, rapid changes related to forest operations have been observed in the forestry sector in Poland. A growing number of harvesters, an increased volume of harvested timber and a larger proportion of broadleaved species are considered the most important. The objective of this paper was to recognise the dynamics of harvester fleet change in Poland. In particular, there was an emphasis on finding out: 1) the total number of harvesters currently used in Poland (with respect to regions), 2) where and what type of machines were bought, and 3) which main factors influence the occurrence of these machines. In January 2014, a survey was sent to all forest districts. Questions related to harvesters and relevant for this paper included information about: 1) the number of harvesters in use, 2) the serial number of each harvester, 3) place of purchase (within the country or abroad), 4) status of the machine when bought (new or used), and 5) the forest district, in which an open tender was won for 2014. To avoid double counting the same harvester working in two or more forest districts, the serial number of each machine was used for identification. There were 368 harvesters reported in the survey in early 2014, although at the end of 2015 this number rose to 530 machines. The Central−West, North−West and North of Poland had the highest number of harvesters. Most of the harvesters were bought as used, though there may be a growing trend towards the purchase of new machines. A strong correlation was observed between the number of machines used in a region and the total area of lowland coniferous sites and forests, as well as the volume of harvested merchantable softwood. Currently, private forests and broadleaved species are the main factors limiting the application of harvesters in Poland.
Cut-to-length technology for broadleaved species is a novelty in forest operations, also causing various difficulties. The purpose of the study was to find effects of an application of the CTL 40HW head1 for broadleaves mounted on the UTC 150-6LS harvester used in a thinning operation in a birch stand in northern Poland. For this, productivity, the level of damage in the remaining stand and soil disturbances were analysed. The results present a satisfactory outcome: the average productivity was 13.4 m3-h"' (h of operational time). Analysis of the remaining stand showed 4-7% trees with damage. Analysis of the soil on the harvester strip roads showed a bulk density increase of 0.16- -0.21 g em"3. It was also observed that there was lower mean soil moisture after harvesting, though this change was not statistically confirmed. The biggest soil penetration resistance increase was observed after two machine drives: 50% on 30 cm of depth and after a single drive 45% on 10 cm of depth.
The paper presents analysis of tree damage after early thinning in lowland spruce stands. Percentage of tree with damage and weighted damage index (WDI) were considered. Three different thinning operations were analysed, in which different cutting method was applied. The smallest level of damage was observed when short wood system (SWS) was used. There were no significant differences between frequency of damage when full tree (FTS) and long wood (LWS) systems were compared.
The paper studies tree damage after late thinning operation in lowland spruce stands. The research was done in the 4th age class stands, where three different methods of timber harvesting were applied: full tree system (FTS), long wood system (LWS), short wood system (SWS). The lowest level of damage was observed in SWS.
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