Influence of Roe Deer on the State of Undergrowth in Oak Groves at the Karadag Nature Reserve

摘要

This paper presents data on the state of stands and undergrowth of the main forest-forming species at the Karadag Nature Reserve in oak forests of downy oak (Quercus pubescens) and sessile oak (Q. petraea) under the conditions of an excessive density of the European roe deer (Capreolus capreolus). By 2016, the exponential growth in the number of roe deer in the reserve, which has been observed since its establishment in 1979, led to an increase in its number to 750 individuals and density of up to 437 individuals per 1000 ha, which is 10 times higher than the norm. At the same time, the level of damaged undergrowth increased from 7.6 to 88.9 in sessile oak and from 8.4 to 83.7 in downy oak. This has resulted in a decrease to an absolute minimum in the numbers of the medium and the complete absence of large undergrowth in both sessile oak and downy oak. The alignment of tree species in abundance (estimated by the Berger-Parker index) is 1.2 for sessile oak stands and 1.18 for downy oak stands; the undergrowth is 3 and 1.6, respectively. At the Primorskoe Forestry located next to the reserve, which exhibits a relatively satisfactory density of roe deer (37 individuals per 1000 ha), damage to the undergrowth of the main species was 5.5 in sessile oak groves and 7.2 in downy oak groves. In the Primorskoe Forestry oak forests, alignment of tree species in abundance is 1.25 for sessile oak and 1.54 for downy oak and 2.15 and 2.11 for their undergrowth, respectively. Based on cumulative data, it is concluded that even providing the conditions of a super-high density of ungulates, oak forests of the Karadag Reserve retain the ability to regenerate through an increase in the density of small undergrowth (sessile oak groves) and alignment of the undergrowth species (downy oak groves). The role of the overabundance of roe deer in the reserve is negative in relation to the reproduction of the main species and positive in regards to biodiversity in terms of the alignment of tree species of the undergrowth in abundance.