ABSTRACT:The paper contains results of comparative investigations of crawler and wheeled skidders regarding their effect on soil surface, undergrowth and rut formation during mountain timber harvesting. It was shown that the extent of erosion resulting from damage to the soil surface depends on the steepness and length of slopes during both construction of skidding tracks and skidding by tractors. Considering the current condition of development of timber harvesting machinery, the use of crawler machines is the main method for transportation of cargos in regions with difficult access.

Permanent attributes of timber harvesting are a number of potential environmental risks, each of which can cause significant damage to the environment. The intensive development of technology and the improvement of industrial production processes have led to a significant increase in technogenic impact both on increasing catastrophic natural disasters and on the global climate change formation. The adoption of the World Environmental Constitution by all the states would be an effective means of regulating and minimizing these negative processes. Timber harvesting is one of the most dangerous types of technogenic impact on the forest environment, as the forest stand, young growth, natural watercourses and soil are damaged during logging and transportation. However, the degree of the negative impact of timber harvesting can be reduced to an ecologically acceptable level, and technical indicators of the use of timber-hauling machinery can be brought to economically feasible values by properly assessing the intensity of the environmental risk of taking a decision on certain technical and technological issues and the implementation of environmental management of this process. The article presents some approaches to the creation of GIS spatial planning model of transport development of forest-exploitation area based on the cost estimation of timber skidding considering technogenic impact of forest machines. The development of the model of forest transportation planning is a complex task. In order to solve this task, the system under investigation should be divided into separate interconnected modules, each acting as its own model: the models for forest transportation planning, the database, formulation of the task, the results of modeling, an analysis of transport movement possibilities, an analysis of environmental damage, the assessment and improvement of the existing forest road network. Concerning the proposed model and methodology that is based on the analysis of potential environmental risks associated with the rutting and cost-assessment of timber skidding, we have obtained the model map of environmentally-acceptable types of timber-hauling machines for a real forest exploitation area, the Rozhanka forest district, the Slavsk State Forestry Enterprise in particular. The proposed model makes it possible to substantiate environmentally safe and economically feasible ways of skidding, estimate the ratio of transport development of a forest area using various terrestrial technical means (wheeled and crawler tractors or cable systems), as well as to outline the possible occurrence, intensity and spread of environmental hazards associated with timber harvesting.