B. Papp szerk.: Studia Botanica Hungarica 33. 2002 (Budapest, 2002)

Bebya, S.: The fir forests of the Caucasus Mountains and considerations on their preservation

Setting cones of young trees is occasional. Spontaneous Abies stands of different age provide abundant seed crops both in quantity and quality for a continuous renewal. On 1 hectare the seed yield of Abies nordmanniana reaches 149 kg and 1,062 thousand pieces of good quality. Thus, harvesting and reforestation in these forests may be based mainly on natural revival of the species, without going into artificial ways of regeneration (BEBYA 1973). The best natural renewal is observed in the so-called "mixtaherbosum" Abies forests, where the undergrowth is dominated by Vaccinium and Festuca. Regeneration is satisfactory in the Abies forests with an undergrowth of Ilex aquifolium. However, renewal is weak in the Abies stands characterised as "luzulosum" and "filicosum" with an undergrowth of Prunus/Laurocerasus and Rhododendron. Within these groups of forest types renewal shows better values at 0.6 stand cover (60%) in the groups of "festucosum" and "luzulosum" types with an undergrowth of Vaccinium and Ilex aquifolium, and at 0.5-0.6 stand cover in the case of the "mixtaherbosum" ones. In the "filicosum" group better renewal can be expected at 0.6 stand cover. These indices must be taken into consideration when planning tree felling in the Abies forests. In natural openings, Abies regenerates well in the forest floor. Within the group of forest types the process of renewal depends mainly on the size and form of openings, and on the steepness and exposure of the slope. In case of the "festucosum" and "mixtaherbosum" Abies forests windows of middle size, with a diameter from 18 to 24 metres, regenerate the best. The study of the virgin Abies forests in the Caucasus has conclusively shown that age unevenness and a well structured and complex composition of vertical layers is a basic characteristic of the stands of all forest types. The forests reveal a great variation of tree age (up to 450-500 years), tree height (up to 60 m) and trunk diameter (up to 2 m). Age dynamics The distinguishing peculiarity of the Abies nordmanniana old-growth forests is the continuous character of age dynamics. This is a continuous process in which old, dying trees or groups of mature trees are continually being replaced by young(er) ones. In these forests, in general, all stand age groups and saplings are always present, which contributes greatly to the stability of the stands. This observation also refutes the misconclusion of a certain fir forest development theory, according to which the virgin (mature) forests of Abies nordmanniana of different age are replaced by younger stands and again these grow into old-growth forests to be replaced by younger ones. The continuous process of natural renewal, the com-