Ecological assessment of dead woodvolume in hornbeam-oak forest in «Medobory» Nature Reserve

The volume of coarse woody detritus in the 139year-old hornbeam-oak forest stand of natural origin on the territory of the «Medobory» Nature Reserve have been studied. The study of dead wood was carried out on a sample plot (0.24 ha) by the method of continuous accounting. It was found that the volume of woody detritus in the forest ecosystem is 108.8 m3∙ha–1 and consists of fallen (32.1%) and standing (67.9%) deadwood. The main part of the dead wood volume is formed by two tree species — common oak (Quercus robur L.) (49.1%) and wychelm (Ulmus glabra Huds.) (48.4%). In general, woody detritus is characterized by I–V classes of decomposition, while detritus of decomposition stage II prevails (40.9%), shares of other stages are slightly smaller: I (27.8%), III (18.6%) and IV (11. 1%). The share of detritus of the last (V) decomposition stage is insignificant (1.6%). The volume of standing dead wood is 73.9 m3∙ha–1 and is formed by whole and broken dead trees. In terms of tree species composition, common oak has a significant advantage (65.4%), wychelm has a much smaller share (33.7%), and the share of hornbeam (Carpinus betulus L.) and small-leaved linden is insignificant (Tilia cordata Mill) (less than 1.0%). In the total standing dead wood volume, wood of decomposition stage IIsignificantly predominates (43.6 m3∙ha–1, 59.0%), compared with stage I (30.3 m3∙ha–1, 41.0%). Volume of fallen dead wood is 35.0 m3∙ha–1 and is formed by whole fallen trees, fragments of felled trees (trunks) and rough branches. In terms of species composition, woody detritus of which elm predominates (27.8 m3∙ha–1, 79.7%), much less common oak wood (5.1 m3∙ha–1, 14.6%) and common hornbeam (2.0 m∙ha–1, 5.7%). Fallen dead wood is represented by four stages of decomposition (II–V). In terms of volume, decomposition stage III has an absolute advantage (20.2 m3∙ha–1, 57.9%), detritus of stage II is much less (12.1 m3∙ha–1, 34.7%), and the shares of other stages are insignificant. The predominance of standing dead wood in the total dead wood volume, as well as the dominance of detritus of I and II decomposition stages due to the relatively short period of strict regime of nature conservation, during which the forest ecosystem developed without human intervention, and the impact of forestry activities (selective sanitary cuttings and fallen dead wood removal) in the past.