Structure of Old-growth Pinus heldreichii forests in Pirin Mountains

University of Forestry, Dendrology Dept., BG – 1756 Sofia, Bulgaria


RANGELOVA, P. and M. PANAYOTOV, 2013. Structure of old-growth Pinus heldreichii forests in Pirin Mountains. Bulg. J. Agric. Sci., Supplement 2, 19: 273–276


Bosnian pine (Pinus heldreichii Christ) is a tertiary relict and Balkan sub-endemic species. Its communities are of high conservational value because they are extremely rich in rare and endemic plant and mushroom species. In Bulgaria, Pinus heldreichii forests are found only in the Pirin and Slavyanka Montains. Despite the necessity of better knowledge of the species and the forests, many questions are still poorly studied.
The goal of this study is to explore the structure and natural dynamics of old-growth Pinus heldreichii forests in Pirin. Four regions were selected in which four sample plots were set. Within them basic characteristics of each tree were measured. Tree ages, growth dynamics and the influence of external abiotic factors were studied. The results were compared with the results from a previous study of younger forests in Pirin. The explored old-growth forests are characterized by much smaller number of trees per 1 ha compared to younger forests. In most of the plots, there are evidences of at least several fires. Regeneration is isolated mostly on dead wood with high class of decomposition. Dominant trees are more than 250 years old. Our data might be valuable in other ecological studies, that need to have better understanding of forest structure and history and might serve as a basis for definition of criteria for old-growth Pinus heldreichii forest.

Key words: old-growth forests, Pinus heldreichii, structure, Pirin Mts.
Abbreviations: DBH – diameter at breast height; CWD – coarse woody debris; PIHE – Pinus heldreichii Christ; PIPE – Pinus peuce Griseb.; PIMU – Pinus mugo Turra; PCAB – Picea abies Karst.; ABAL –Abies alba Mill; SOAU – Sorbus aucuparia L.

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