Soil natural recovery process and Fagus orientalis lipsky seedling growth after timber extraction by wheeled skidder

Abstract

The growth and quality of natural seedlings are important goals of forest management in uneven-aged high stands. In this study, the recovery process of the physical and chemical properties of soil, as well as growth variables of beech seedlings on the skid trails after skidding operations in three time periods (10, 20, and 30 years) were investigated in the Hyrcanian forests of Iran. Results revealed that the soil chemical properties (organic C, total N, and pH) were fully recovered after 20 years, while soil physical properties (bulk density, porosity, and penetration resistance) were not yet fully recovered even after 30 years. The values of growth characteristics (stem and root system) and the quality index of beech seedlings were not statistically different from those of the control area ones after 20 years. According to our findings, the process of recovering soil characteristics after forest operations is long and takes more than 30 years. Considering the effect that soil compaction can have on seedling establishment and growth, proper planning of the forest operation is needed to limit the negative effects of forest operations, which meets the requirements of sustainable forest management. We suggest designing skid trails with a minimum distance of 140 m from each other and with a longitudinal slope of less than 15%, in compliance with the principles of best management practice (BMP).