Natural disturbances in the forests and bark beetle outbreaks over the period 2015-2024 in the Rhodope Mountains, Bulgaria

Damage caused by abiotic factors (snowfalls, snowbreaks, windfalls and windbreaks) and by bark beetle outbreaks was studied over the period 2015-2024 on the territory of four State Forest Enterprises (SFEs) and two State Hunting Enterprises (SHEs) at the South Central State Enterprise – Smolyan in the Rhodope Mountains, Bulgaria. Three severe natural disturbances were analysed, with different silvicultural approaches to removing damaged wood and preventive measures to reduce bark beetle outbreaks, as follows: i ) the snowfall on 8 March 2015 affected mainly pine plantations, leaving about 1.5 million m 3 of damaged wood in the stands; ii ) the windfall and windbreak on 18 January 2018 in natural coniferous forests on the territory of the SFE Smolyan, where the affected wood was removed from damaged stands within less than a year, and subsequent infestations by the European spruce bark beetle ( Ips typographus ) were controlled by trap trees; iii ) the windfall and windbreak on 17 September 2022 on the territory of SFEs Borino, Dospat and Shiroka Polyana, and SHEs Borovo and Izvora – Devin, in which initial settlements of I. typographus and of the sharp-dentated bark beetle ( I. acuminatus ) on the felled wood were systematically destroyed with chainsaws equipped with bark peeling modules. In 2015, the large amount of wood left in damaged stands resulted in catastrophic attacks by I. acuminatus on Scots pine ( Pinus sylvestris ) and by I. typographus on Norway spruce ( Picea abies ) trees in the vicinity of snowbreak areas. In 2018, the damaged trees were removed from the affected stands within less than a year, and the wood was used successfully as trap trees for pest control. In 2022, initial infestations of I. typographus and I. acuminatus were systematically destroyed on fresh-cut wood, thereby reducing bark beetle attacks in the studied State Forest and Hunting Enterprises.