Ecological assessment of dead wood volume in hornbeam-maple-ash forest in «Medobory» Nature Reserve

The volume of coarse woody detritus in the 112- year-old hornbeam-maple-ash forest stand of natural origin in «Medobory» Nature Reserve have been studied. The study of dead wood was carried out on a sample plot (0.48 ha) by the method of full accounting. The volume of woody detritus in the forest ecosystem is 62.7 m3∙ha–1and consists of fallen (82.9%) and standing (17.1%) deadwood. The main part of the dead wood volume is formed one tree species — common ash (Fraxinus excelsior L.) (93.0%). In general, woody detritus is characterized by I–IV classes of decomposition, while detritus of decomposition stage I prevails (44.2%), shares of other stages are slightly smaller: II (30.9%), III (23.6%) and share of stage IV is insignificant (1.3%). No coarse detritus of the last (V) decomposition stage was found on studied plot. The volume of standing dead wood is 10.7 m3∙ha–1 and is formed by broken dead trees. In terms of tree species composition, common ash dominates (94.4%), and the share of hornbeam (Carpinus betulus L.) is insignificant (5.6%). In the total standing dead wood volume, wood of decomposition stage I predominates (9.4 m3∙ha–1, 87.9%), compared with stage II (1.3 m3∙ha–1, 12.1%). Volume of fallen dead wood is 52.0 m3∙ha–1 and is formed by whole fallen trees, fragments of fallen trees (trunks) and rough branches. In terms of species composition, woody detritus of common ash predominates (48.2 m3∙ha–1, 92.7%), and the proportions of other species are insignificant. Fallen dead wood is represented by four stages of decomposition (I–IV). In terms of volume, decomposition stage I (18.3 m3∙ha–1, 35.2%) and stage II (18.1 m3∙ha–1, 34.8%) prevail, detritus of stage III is less (14.8 m3∙ha–1, 28.5%), and the share of stage IV is insignificant. Low volumes of late decomposition stages of woody detritus is explained mainly by influence of forestry activity in the past and relatively short period of strict regime of nature conservation, during which the forest ecosystem developed without human intervention.