Distribution, productivity and natural regeneration of black alder (Alnus glutinosa (L.) Gaertn.) in Ukrainian Polissya

The aim of the study was to assess the current state and productivity of black alder (Alnus glutinosa (L.) Gaertn.) stands and determine the optimal conditions for the emergence and further growth of its natural regeneration in Ukrainian Polissya. The area of black alder stands in Ukrainian Polissya (Ukrainian forest zone) is 162,348 ha, reaching 8.4% of the total forest area. Volyn Region has the largest area of alder stands within Ukrainian Polissya (61,271 ha covering 37.7% of the total area). In the forests of this region, a more detailed study of the current condition, productivity, growth and regeneration of alder stands was performed. The natural regeneration under the alder canopy was characterized as poor. The largest numbers of alder seedlings (1,600–1,800 stems per ha) were recorded under the canopy of 76–78-year-old stands with a relative density of stocking of 0.63–0.70 and 80–100% of alder in their composition. Naturally regenerating alder seedlings had mainly group distribution on the area (occurrence is up to 40%). These specificities should be taken into account to promote natural seed regeneration of alder stands.