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Issues: 1-5 | 6-10 | 11-15 | 16-18
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ENVIRONMENTAL ESTIMATION OF MECHANIZED TECHNOLOGIES FOR REGENERATIVE CUTS IN MOUNTAINOUS CONDITIONS
 

Dimitar Georgiev and Stanimir Stoilov
 

Department of Technologies and Mechanization of Forestry, University of Forestry, 10, Kliment Ohridski blvd, 1756 Sofia, Bulgaria. E-mail: dimitarg@ltu.bg
 

Abstract:

An environmental estimation is made of regenerative cuts in mountain beech (Fagus sylvatica L.) stands, based on a motormanual prime processing and transportation by wheel cable skidders. After the mechanized regenerative cuts, about one-third of the residual trees are damaged, fortunately most of them superficially. Predominantly the tree roots and stems are damaged. Inside the stands, the number of damaged trees is smaller, whereas around the skid roads almost half of the trees are damaged. In the first case, the residual trees are damaged by the felled trees (mainly higher than the first 1 m of the stem). In the second case the damages are caused by the skidded stems. The results show that the percentage of damaged understorey is about 16.89%, including 80% of it recoverable. To reduce tree damages along the skid roads and especially those along the curves, it is advisable to use some protective devices for prevention. To minimize the damages on the understorey it is necessary to use protective X-devices, diverting rollers and cones on the front of the logs. It is advisable to improve the professional skills of the loggers and to introduce effective stimulations for environmentally-sound logging operations.
 

(Forestry Ideas, 2010, Vol. 16, No. 2) [Download]
Downloads: 905

friction coefficients seeds Analysis
of some coniferous tree species
 

Konstantin Marinov and Kiril Lyubenov
 

Department of Technology and Mechanisation of Forestry, Faculty of Forestry, University of Forestry, 10 Kliment Ohridski Blvd., 1756 Sofia, Bulgaria. E-mail: kmarinov_ltu@abv.bg
 

Abstract:

In this paper an experimental study is exposed which has been conducted for determining the angles and the friction coefficients of seeds of some coniferous tree species. These parameters are used in the design and construction stages of forest planters and seeding machinery. These parameters can also be applied in the technological research of many forestry processes such as: dewinging, cleaning, sorting, seeds sowing etc. The object of research are seeds of some of the main coniferous tree species which are a subject of economic activity in our country - Scots pine (Pinus sylvestris L.), Black pine (Pinus nigra Arn.), Norway spruce (Picea abies Karst.) and Macedonian pine (Pinus peuce Griseb.). As a result of this study, the angle parameters and the friction coefficients of the studied seeds have been established. Results can be used in the design of forestry machinery and in the research of technological processes connected to the movement and processing of seeds.
 

(Forestry Ideas, 2010, Vol. 16, No. 2) [Download]
Downloads: 815

contribution to the identification
of Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) provenances promising
for Aforestation practice
 

Emil Popov
 

Forest Research Institute - BAS, 132 "St. Kliment Ohridski" blvd., Sofia 1756, Bulgaria. E-mail: emilpopov99@hotmail.com
 

Abstract:

Rapid growth is one of the most valuable characteristics of Douglas fir. In order to make the best use of this feature of its, it is necessary to investigate the growth characteristics of this tree species at level population. The objective of this research is to contribute in identifying promising provenances of Douglas fir in the experimental plantation in Konyavska Mountain. In order to attain the above objective methodologies for establishment and assessment of provenance experiments, early tests and statistics were applied. The average values for height of the trees for a period of five consecutive years: 5, 6, 7, 8 and nine as well as the current height increment for four years for each provenance in the trial plantation established with provenances from the states of Oregon, Washington, Arizona and New Mexico in State Forest Service Kyustendil were estimated. Based on data about the sums of precipitation and air temperature, drought and semi-drought periods were determined for corresponding years. The provenances are determined as promising if they meet the following two conditions: to be at the top of classification according to reached height and current increment in height, and to be of current increment in height influenced by the duration of dry and semi-dry periods to the least extent.
 

(Forestry Ideas, 2010, Vol. 16, No. 2) [Download]
Downloads: 860

DYNAMIC GROWTH MODEL FOR BIRCH STANDS
IN NORTHWESTERN SPAIN
 

Esteban Gomez-Garcia, Felipe Crecente-Campo, Tatiana Stankova, Alberto Rojo, and Ulises Dieguez-Aranda*
 

Department of Agroforestry Engineering, University of Santiago de Compostela. Escuela Politecnica Superior, R/ Benigno Ledo, Campus universitario, 27002 Lugo, Spain. *E-mail: ulises.dieguez@usc.es
 

Abstract:

A dynamic whole-stand growth model for birch (Betula pubescens Ehrh.) stands in Northwestern Spain is presented. In this model, the initial stand conditions at any point in time are defined by three state variables (number of trees per hectare, stand basal area and dominant height), and are used to estimate total or merchantable stand volume for a given projection age. The model uses three transition functions expressed as algebraic difference equations to project the corresponding stand state variables at any particular time. In addition, the model incorporates a function for predicting initial stand basal area, which can be used to establish the starting point for the simulation. Once the state variables are known for a specific moment, a distribution function is used to estimate the number of trees in each diameter class by recovering the parameters of the Weibull function, using the moments of first and second order of the distribution. By using a generalized height diameter function to estimate the height of the average tree in each diameter class, combined with a taper function that uses the above predicted diameter and height, it is then possible to estimate total or merchantable stand volume.
 

(Forestry Ideas, 2010, Vol. 16, No. 2) [Download]
Downloads: 1347

density and biomass of the WILD trout
IN SOME BULGARIAN RIVERS
 

Vasil Kolev
 

Department of Wildlife Management, University of Forestry, 1756, 10 St. Kl. Ohridski Blvd., 1756 Sofia, Bulgaria. E-mail: vassilie@abv.bg
 

Abstract:

The wild trout biomass density in four tributary streams of the Maritza river (Topolnitsa, Stryama, Yadenitsa and Chepinska) was investigated by electrofishing. The study was carried out in 100 m long closed test areas, from mid summer to autumn 2008. The theoretical density for two consecutive catches was calculated. It was found that the areas of populations of wild trout in the Topolnitsa and Stryama creeks are fragmented and with a very low-rate density. The theoretical density of wild trout estimated is as follows: for the Chepinska stream - 446 ha-1 and for the Yadenitsa stream - 608 ha-1. The theoretical number of wild trout with a length of 23 cm and more was calculated for the Stryama stream - 15 ha-1, for the Yadenitsa stream - 12 ha-1, and for the Chepinska stream - 4 ha-1 respectively. Within the four studied creeks the highest rate of wild trout theoretical biomass was found to be that of the Yadenitsa stream - 26.27 kg.ha-1, followed by stream Chepinska with 20.43 kg.ha-1. The quantity of fish allowed for fishing, with a length of 23 cm and more, according to the Law (Anonymous 2006), was very low in all the four creeks that were studied.
 

(Forestry Ideas, 2010, Vol. 16, No. 2) [Download]
Issues: 1-5 | 6-10 | 11-15 | 16-18