Environmentally Sound Harvesting Technologies in Commercial Forests in the Area of Northern Velebit – Functional Terrain Classification

Background and Purpose: The role of environmental effects in timber harvesting has great importance in decision making and planning logging operations. Consequently, more emphasis should be put on a planning system so that environmentally sensitive sites for a certain harvesting system can be recognized and the most suitable machinery selected for given terrain conditions. Material and Methods: Four main data sources have been used for the model of ecoefficient harvesting system prediction: 1) a digital elevation model (DEM), 2) a digital network of forest roads, 3) forest inventory data and 4) ecoefficient limitations for harvesting systems. Software ArcGIS 9 was used for GIS processing and data analysis. Results: A model for selecting an ecoefficient harvesting system for commercial forests of Northern Velebit is based on three influencing factors: terrain slope, extraction distance and breast height diameter of trees. Based on the model, a harvesting system is determined for each forest subcompartment. The results show that breast height tree diameter restricts mechanized felling and processing. Fully mechanized harvesting systems could be used only over 7.27% of the researched area. Ground based extraction represents the main technology. Conclusions: In order to establish functional terrain classification, a model for determining an ecoefficient harvesting system should comprise a geographic information system, and terrain and forest stand data. Specific terrain (limestone combined with relief characteristics) and forest stand conditions (mixed selective forests with natural regeneration) limit the application of some harvesting systems which would otherwise be environmentally acceptable in many other cases