Soil Changes and Plants Reaction to Road Construction in a Temperate Mixed Forest.

This study aimed to investigate the effect of road construction on plant species composition, and tree and shrub regeneration in relation to soil properties. Ten transects were established perpendicular to the main axis of the road that went up to 35 m inside the forest. The sampling was done at plots located at 5, 15, 25, and 35 m along each transect. The relevé method of Braun--Blanquet was used for vegetation sampling. A total of 40 relevés were established, with each relevé covering an area of 100 m² (10 m x 10 m), to count the number of woody species regeneration. To study the physical and chemical properties of soils, composite soil samples were collected from the depth of 0-10 cm from three cores taken near the center of each plot. Results showed that plant species were classified into two groups using two-way indicator species analysis. Multivariate analyses (principal component analysis and canonical correspondence analysis) were used to identify the most important soil variables and determine relationships between plant species composition and soil properties. Classification of vegetation into two recognizable groups indicated that species composition had been modified based on distance from the road. In plots near the road, moisture content, saturation, clay, porosity, and organic carbon decreased, while the amount of sand and silt, bulk density, and pH increased. Findings showed that roads could have significant influence on adjacent ecosystems, and therefore, it is essential to estimate the extent of the road-effect zone and to determine the environmental changes due to forest roads. [ABSTRACT FROM AUTHOR]