MONITORING OF HEALTH STATUS OF QUERCUS CERRIS L. IN THE EASTERN BALKAN RANGE AND THE LUDOGORIE (BULGARIA)
MARGARITA GEORGIEVA*, DIMITAR NEDJALKOV, GEORGI GEORGIEV, MARIA MATOVA,
GERGANA ZAEMDZHIKOVA, PETAR PETKOV, PLAMEN MIRCHEV
Forest Research Institute – Bulgarian Academy of Sciences, 132 “St. Kliment Ohridski”, Sofia, Bulgaria
*Corresponding author: margaritageorgiev@gmail.com
Keywords: Quercus cerris, monitoring, health status, Bulgaria
Abstract: The objective of the present study was to examine the health status of Quercus cerris L. stands in the region of the East Balkan Range and the Ludogorie for the period between 2009 and 2018, on the base of forest monitoring conducted in Bulgaria under the ‘International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests’ (ICP Forests). The health condition of Q. cerris trees was surveyed annually in seven permanent sample plots (PSPs) based on the assessment of defoliation and damages caused by biotic and/or abiotic factors. For the entire studied period, it was established that Q. cerris stands was in relatively good condition. Decline of single trees due to their natural maturity was observed. In next years, a persistent tendency for deterioration of tree condition was recorded, and at the end of the studied period, the damaged and dead trees exceed the number of healthy ones. The results of ten-year monitoring shown that fungal pathogens caused the most significant impact in this process and the number of affected trees was nine times more than damages caused by insects and abiotic factors. Among the complex of pathogens, the influence of Hypoxylon mediterraneum (De Not.) J.H. Mill. was the most considerable on sample trees. The pathogen was established in 85% of PSPs, and in some of them almost all trees were affected. Dryomyia circinans (Giraud, 1861) and representatives of Geometridae were the most numerous of the insect pests. Formation of frost cracks was often noticed on sample trees in result of low winter temperatures. Illegal felling of trees in PSP is still a huge problem in studied PSPs, as in two of them all assessed trees were completely cut down.