Canopy influence on soil properties in Austrian pine artificial stands

The aim of the present study is to track changes in the canopy (cover-abundance of the tree layer) of vegetation and cover of the forest litter, and the relationship between them and the dynamics of soil parameters in Austrian pine (Pinus nigra Arn.) plantations. The objects of study are 50-80-year-old artificial plantations of Austrian pine located in the xerothermic oak belt of five mountains in the area of Sofia. In each mountain, three test plots (SPs) were laid out, each measuring 400 m2 (Table 1). The main reason for choosing PP is the cover abundance of the first layer. Within each SP, the following metrics are measured: cover-abundance (%) of vegetation in each layer; the cover of plant litter (%). From all SPs, soil samples were taken from three depths: 0-10 cm, 10-20 cm and 20 -30 cm. An analysis of the content of soil organic matter was carried out, including: total nitrogen (N), the C/N ratio – calculation method, the reaction of the soil solution (pH) in the aqueous extract and the mechanical composition of the soil. The results show that the properties of the studied soils change to a significant extent in accordance with the cover abundance, especially in the first floor of the vegetation. Soil organic matter content, C/N ratio and mechanical composition are the indicators that most clearly reflect the relationship between the canopy and the cover of plant litter on the one hand, and soil properties. The proven, statistically significant differences in the values of these indicators emphasize the role of vegetation in soil-forming processes, the formation and change of soil fertility.