Purpose of this thesis was to find out how frozen ground and ground, covered with snow, effect on ground damage. We were most interested in minimal depth of frozen ground or depth of snow cover, at which ground damage is minimal. Our purpose was also to find out how depth of frozen ground and snow cover changes through years. Results were divided to regional units. We used two methods, the first was questionnaire for professional workers in Slovenian forest service, Slovenian state forests and other wood production contractor firms. Second method was analysis of data from meteorological stations. We were interested in snow depth and temperature of ground on depth of 5 cm, 10 cm and 30 cm. Results of questionnaire showed that snow depth of 29 cm is required for wood production with minimal ground damage. When soil is frozen, at least 17 cm of frost is required to prevent ground damage. Results of the second method showed us that the most snow precipitation falls in Julian Alps and Dinaric Alps. Bled and Kočevje regional units have the highest mean number of days with snow cover above 29 cm. Average snow depth in Slovenia in last 5 years has changed from 28,5 cm to 10,7 cm. The most days, suitable for work on frozen ground last from the end of November to March.