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Issues: 1-5 | 6-10 | 11-15 | 16-19
Downloads: 97

PRODUCTIVITY AND COSTS OF CABLE YARDING IN GROUP SHELTERWOOD SYSTEM IN DECIDUOUS FORESTS

Stanimir Stoilov

Department of Technologies and Mechanization in Forestry, University of Forestry, 10 St. Kliment Ohridski Blvd., 1797 Sofia, Bulgaria. E-mail: stoilovs@ltu.bg

Abstract:

The aim of the present study was to improve the use and operational efficiency of the truck-mounted tower yarders in deciduous stands and to determine the time, log’s volume transported per turn by the yarder, as well as the yarding costs. The study was carried out in the Sredna Gora Mountains, Central Bulgaria, in deciduous stand with species composition of European beech (90 %), European hornbeam (10 %). The mean productivity of truck-mounted tower cable yarder at shift level is close to the maximum for that type (9.12 m3·PMH-1 and 8.41 m3·SMH-1). In order to improve the yarder productivity a remote control of the carriage is advisable to be used, also used by the choker-setter. In this way the loaded carriage could wait for the operator before the landing. Another option to reduce choker-setter‘s fatigue and to decrease the time for lateral outhaul and hook is to use a carriage with mechanical slack-pulling. The gross costs for yarding uphill a whole deciduous tree by the studied tower yarder were calculated at 146.52 € per productive machine hour and 13.02 € per m3. In the distribution of the gross costs, labour costs (21.44 %) are lower than variable costs (29.86 %) and fixed costs (26.84 %). The results from the study are useful to integrate the cable yarders in group shelterwood system and to achieve economic and environmental efficiency of timber transportation in deciduous forests in sensitive sites.

 

 

 

 

(Forestry Ideas, 2021, Vol. 27, No. 2) [Download]
Downloads: 85

VERIFICATION OF FOREST HIGH RESOLUTION LAYERS 2015: TREE COVER DENSITY AND DOMINANT LEAF TYPE IN BULGARIA

Youlin Tepeliev(1), Radka Koleva(1)*, and Ventzeslav Dimitrov(2)

1. University of Forestry, 10 Kliment Ohridski Blvd., 1797 Sofia, Bulgaria.
*E-mail: rad_koleva@abv.bg, rad.koleva@gmail.com
2. Space Research and Technology Institute at the Bulgarian Academy of Sciences,
Acad. G. Bonchev Str. Block 1, 1113 Sofia, Bulgaria.

Abstract:

The high-resolution layers (HRLs) are Pan-European land cover datasets aimed at monitoring soil sealing (imperviousness, forest, grasslands, wetness and water, and small woody features. The main purpose of this article is to present the methodology and results from verification of two Forest HRL products for the 2015 reference year for Bulgarian territory: Dominant Leaf Type (DLT) and Tree Cover Density (TCD). The verification task aims at identifying systematic classification errors and the results are supposed to be used for improvement in future product updates. Qualitative approach for assessment of the HRL quality is applied in two steps, called General overview of data quality and Look-and-feel verification. The latter is performed within dedicated strata through non-random sampling, checking HRLs for omission and commission errors. We show results from a verification at country level based on local expertise and best available in situ data. We also provide comments and recommendations concerning commission and omission strata. Several cases of both of the above types of errors are identified and analysed in the DLT and TCD high resolution layers. Despite of errors found, both DLT and TCD receive a ‘good’ mark, and the same rating prevails in the strata level evaluation.

(Forestry Ideas, 2021, Vol. 27, No. 2) [Download]
Downloads: 86

IMPACT OF THE WATER TEMPERATURE INCREASE IN THE DOSPAT DAM ON THE KEY INDICATORS CHARACTERIZING AQUACULTURE EFFICIENCY

Martina Stancheva

Wildlife Management Department, University of Forestry, 10 St. Kl. Ohridski Blvd., 1797 Sofia, Bulgaria. E-mail: martina_vas.nik@abv.bg

Abstract:

Climate change is among the main challenges for achieving sustainable development of aquaculture. It is likely to cause changes in the temperature and hydrological regimes of inland waters. Air temperatures in the region of Dospat Dam have been rising over the past 15 years. This impacts the water temperature in the dam and on rainbow trout (Oncorhynchus mykiss) farming in it. The average water temperatures measured in the surface layer in the 1970s (10.18 ±6.79 °C), and the 1980s (10.16 ±7.07 °C) were lower than the ones today (12.40 ±7.12 °C). Higher summer temperatures of the water in the dam have an unfavourable impact on the key biological indicators which determine the aquaculture efficiency, such as fish growth (AG, g), survival rate of fish (SR, %) and feed conversion ratio (FCR). The water temperatures in July and August are above 18–20 °C. This period is marked by the lowest fish growth and the lowest survival rate of fish. At the same time, feed conversion ratio is 3.3:1 which is higher than recommended in feed charts and it is economically inefficient. Global warming is likely to have a negative impact on the development of cold-water aquaculture in Bulgaria. It will result in a longer production cycle and higher costs.

(Forestry Ideas, 2021, Vol. 27, No. 2) [Download]
Downloads: 81

OPTIMIZATION OF OAK FOREST MANAGEMENT PRACTICES IN SOUTHERN GREECE

Panagiotis Lattas(1)*, Pavlos Chasilidis(2), Aggeliki Tsakona(3), Natalia Golfinopoulou(4), and Theocharis Zagas(5)

1. Forest Service of Pyrgos Ilias, PC 27131 Pyrgos, Greece. *E-mail: lattaspan@yahoo.gr
2. Forest Service of Edessa Pella, PC 58200 Edessa, Greece. E-mail: hasp68@gmail.com
3. Forest Service of Ilias, PC 27131 Pyrgos, Greece. E-mail: kitsakona@yahoo.gr
4. Ionian University, Department of Environment PC 29100, Zakinthos, Greece. E-mail: natalia7890@hotmail.com
5. Department of Forestry and Natural Environment, Aristotle University of Thessaloniki,
PO Box 262, PC 54124 Thessaloniki, Greece. E-mail: zagas@for.auth.gr

Abstract:

The oak forests in Mediterranean are widespread and dynamic natural ecosystems. For millennia, oak forests have provided vital ecosystem services to humans in the Mediterranean including social, economic and environmental services and goods; however, in parallel, human exploitation has altered their structure. Consequently, targeted management approaches are required to optimize the production. In the current study we analyzed the structural characteristics of the Foloi oak forest (Quercus frainetto) in the wider area of Ancient Olympia, Peloponnese, Greece. An extensive fieldwork was applied in 29 randomly located plots in order to collect dendrometric characteristics of 938 individual trees. The collected data were used to build models for estimating tree age, tree height and canopy length from diameter at breast height (DBH). All models were found to have an adequate fit and provide useful tool for the assessment of site structural and growth characteristics. Furthermore, we present a model for assessing site quality from topographic characteristics such as slope and exposition. Finally, we employed a stand visualization tool to get a graphical representation of the stand structure, which can be used in order to adopt appropriate silvicultural practices. We believe our findings will provide useful tools to forest managers and practitioners for the sustainable management and restoration of oak forests.

(Forestry Ideas, 2021, Vol. 27, No. 2) [Download]
Downloads: 112

EVALUATION OF DORMANCY-BREAKING TREATMENTS ON SEED GERMINATION OF TWO LEGUMINOUS TREE SPECIES FROM CHOBE DISTRICT, NORTHERN BOTSWANA

Witness Mojeremane(1)*, Kamogelo Makgobota(1), Thembinkosi Mathowa(2), Kakambi Obusitswe(3), Melusi Rampart(1), Demel Teketay(1), Gosiame Neo-Mahupeleng(4), Topoyame Makoi(1), Ronnie Mmolotsi(1)

1. Department of Range and Forest Resources, Faculty of Natural Resources, Botswana
University of Agriculture and Natural Resources, Private Bag 0027, Gaborone, Botswana.
*E-mail: wmojerem@buan.ac.bw; wmojeremane@yahoo.com
2. Department of Crop and Soil Sciences, Faculty of Agriculture, Botswana, University of
Agriculture and Natural Resources, Private Bag 0027, Gaborone, Botswana.
3. Department of Forestry and Range Resources, Ministry of Environment, Natural Resources
Conservation and Tourism, P.O. Box 140, Kasane, Botswana.
4. Department of Wildlife and Aquatic Resources, Faculty of Natural Resources, Botswana
University of Agriculture and Natural Resources, Private Bag 0027, Gaborone, Botswana.

Abstract:

Seed germination experiments were conducted at Botswana University of Agriculture and Natural Resources to determine the best possible pre-sowing treatment methods that maximize seed germination of Albizia versicolor and Faidherbia albida. The experiments were laid out in a completely randomized design (CRD) with 10 pre-sowing treatments, namely the control, mechanical scarification, soaking in concentrated sulphuric acid with four levels of time exposure (15, 30, 45 and 60 min), immersion in boiling water with three levels of time exposure (1, 3 and 5 min) and soaking in hot water (allowed to cool for 24 h). Treated seeds were germinated for 30 days at room temperature (25 °C). The raw data were subjected to analysis of variance (ANOVA). The results showed that seeds treated mechanically, sulphuric acid (all levels), boiling water (1 and 3 min) and hot water had significantly (p < 0.01) higher mean germination percentages than the control and boiling water (5 min) for A. versicolor, whereas for F. albida seeds treated mechanically and exposed to sulphuric acid (all levels) had significantly (p < 0.01) higher mean germination percentages than the rest. Significant (p < 0.01) mean germination time and index were revealed among the treatments for the two species. 

(Forestry Ideas, 2021, Vol. 27, No. 2) [Download]
Issues: 1-5 | 6-10 | 11-15 | 16-19