Młode pokolenie drzew a struktura lasu w rezerwacie Świnia Góra

The Świnia Góra nature reserve (51°03'24" N, 20°42'21" E) with an area of 51 ha is one of the few forests in Poland operating under strict protection for many decades (formally since 1953). Its stands are dominated by fir and beech – two species that are currently showing high growth dynamics and are important in the face of expected climate change. The purpose of the study was to: (1) investigate the state of the forest regeneration layer of the reserve, (2) relate the characteristics of the tree regeneration to certain characteristics of the structure of the canopy layer, and (3) describe, using selected characteristics, the competition between young firs and beeches. The empirical data was collected on 95 concentric sample plots made up of three areas of size related to the dimensions of trees. The average density of trees of the young generation on the whole site was 7226 ±2383 ind./ha (±33.0%) and the sum of their height was 6552 ±1046 m/ha (±16.0%). There were 14 tree species, the most numerous being silver fir (46 ±9%) and beech (35 ±8%). The species compositions of the regeneration layer and the canopy layer partly differed (Morisita index=0.90). In the regeneration, two numerous species of the canopy layer – larch and pine – were missing. The share of species changed with the dimensions of trees (fig. 2). The density and sum of the height of young trees (fig. 3) and the species composition (fig. 4) did not differ much between stands classified into individual natural developmental phases. The influence of the canopy cover on the sum of the height of the regeneration of trees was more pronounced (fig. 5). Also the species composition of the young generation of trees changed with the degree of crowns cover, with this relation in the case of small saplings (h=0.3−1.3 m) being different than in the case of large saplings (d=0.1−6.9 cm) (figs. 7 and 6, respectively). For small saplings, the probability that the tree was a fir and not a beech was low (fig. 8). The periodical increment of the length of the leader shoot changed with the height of the tree and the degree of cover by the crowns of the canopy layer, whereas under the same conditions beech grew faster than fir (fig. 9). In the Świnia Góra nature reserve, the fir seedling (h
Sylwan 165 (1): 30-40