Soils of the “Arboretum” Park in Sochi: signs of degradation

The Sochi Arboretum is located at absolute altitudes of 8–140 m and includes the Lower Park on a low and flat marine terrace and the Upper Park comprising areas of weakly inclined Neogene terraces and steep slopes, which determines the differences in degradation trends: water logging of eluvialsurface-gley zheltozems in the Lower park, and erosion-colluvial processes in zheltozems and grey-humus soils in the Upper park. Both degradation types are not strongly pronounced. The increasing water logging is manifested in the increasing gleyzation and surface water stagnation owing to the breakdown of the drainage system. In the Upper park, water logging is local and confined to small depressions, and the main types of degradation are removal of soil upper layers (erosion) and landslides, especially noticeable on a very steep slope under the natural forest. One more degradation process is the recreational compaction of small paths. The properties of zheltozems are favorable for the development of degradation processes, these are: heavy texture, high density and massive fabric of poorly permeable subsoils, participation of smectite in the clay fraction, as well as landscape features: steep slopes and abundant rainfall.