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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

The Stołowe Mountains National Park was established in 1993. Before that time, most canopies composing it were used for commercial purposes. In consequence, they are mainly spruce mono− cultures with a simplified structure in terms of age and species composition. Since that time, changes in tree stands have consisted in reducing share of spruce and increasing share of deciduous species, which is linked with the gradual dying of the forests and intentional conversion of the stands. The objective of this paper is to determine the overlap between the canopy and the regeneration layers and to specify which forest structure and environmental factors have the greatest impact on the intensity of such overlap. The empirical data was collected on 317 concentric sample plots made up of four circles of a size related to the dimensions of trees. The main species, both in the regeneration and in the canopy layer, included spruce followed by beech. The average density of young generation trees on the whole site was 23394 ±4392 ind./ha (±18.8%) and the average growing stock of tree stands was 384 ±24 m/ha (±6%). The Morisita index, which indicates the overlap between the entire regeneration and canopy layers equalled 0.96. With the use of boosted regression trees, it was found that the main factors affecting the overlap between these two layers are the altitude, the height of tree stand, the share of beech in canopy layer, and the topographic wetness index. The overlap between the canopy layer and the young generation increases along with growing altitude (this trend remains up to altitudes lower than 800 metres above sea level), increasing share of beech and increasing moisture content in the area expressed with the topographic wetness index. It declines along with growing inclination and coverage of the upper layer of trees, with a coverage not exceeding 85%., Sylwan 165 (6): 452-462

The aim of the study was to characterize the state and dynamics of dead wood resources in the stands of the Świnia Góra strict forest reserve, which was excluded from use for a longer period of time (from 1938/1953), and to compare the results with the state and dynamics of living trees resources. The reserve covers 51 hectares of an upland forest in the Świętokrzyska Forest (central Poland). Data was collected in 2000, 2007 and 2014 on 95 systematically distributed 500 m sample plots. The location and dimensions of living trees, standing dead trees (snags, including stumps) and downed trees (logs) on each sample plot were determined and measured. The decay stages of dead wood were estimated using a four−point scale classification. The average volume of dead wood was 198 ±32 m/ha (43 ±8% of living trees) in 2000 and 138 ±17 m/ha (24 ±3%) in 2014 (fig. 1). The ratio of the volume of snags to logs decreased from 30 ±5% in 2000 to 24 ±6% in 2014. Silver fir was the dominant species among both living and dead trees (fig. 2). The share of dead wood volume in decay stages 1 and 2 was the highest among snags, while in stages 2 and 3 – among logs. The number of highly decomposed wood increased in the period 2000−2014 (fig. 3). The decay rate of wood calculated over a 7−year period was more rapid for logs (fig. 4). In the period of 14 years, 119 ±23 m/ha of dead wood underwent a complete decomposition. Volume of trees that died within that period was 59 ±10 m/ha (fig. 5). The complete decomposition of snags amounted to 64 ±10% and logs to 58 ±5% of the initial dead wood volume. The dead wood resources in the investigated period were not balanced: the amount of decayed wood was larger than the amount of wood replenishing the resources. The lack of this balance was due to the lack of the balance of living trees – dead wood resources were insufficiently replenished by trees that had died during analysed 14 years. The dead wood resources at a level of approximately 200−230 m/ha might be balanced via their continuous replenishment by newly died trees in the amount close to the current volume increment., Sylwan 162 (4): 295-304