Fig. 1

Study area, sampling design, and dolines. a Location of the study area in Hungary. b Position of transects within dolines. c Doline dominated by 5–10-year-old forests. d Doline covered with 40–45-year-old forests. e Doline covered with 60–65-year-old forests. f Doline covered with more than 90-year-old forests (photos: Gábor Li and Zoltán Bátori)