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Marcin Szydlarski and Jerzy Modrzyński


The Kaszuby Lake District is located beyond the natural range of Norway spruce, however its share in local forest stands is considerable (14.8%) and its vitality and growth are here not less than within the natural range. The study presents the results of stock-taking of natural regeneration of Norway spruce in this region in year 2002 and 2012 and the relevant silvicultural recommendations. The stock of spruce natural regeneration was taken using the electronic database of the Regional Headquarters of State Forests in Gdańsk. The regeneration was put into following categories: seedlings (height below 0.5 m), lower advanced growth (height above 0.5 m and DBH below 7 cm), higher advanced growth (height above 3 m and DBH above 7 cm) and undergrowth (with dominating self sown spruce). In total 20 834 ha of Norway spruce natural regenerations were listed in year 2002 and 26 016 ha in year 2012 (increase by 24.9%). Most of them occur in fresh sites suited for mixed deciduous forests (LMśw) - in years 2002 and 2012 respectively 52.5% and 50.1%, and fresh sites suited for mixed coniferous forests (BMśw) - in years 2002 and 2012 respectively 30.4% and 32%.

The increase of natural regeneration of Norway spruce in this period was connected with the 23.6% decrease in volume of spruce stands in age of above 40 years.

Majority of spontaneously arriving spruce regenerations turn to the undergrowth, because of unfavorable light conditions under canopy and much to high density of seedlings and advanced growth. Good quality advanced growth on suited forest sites should be uncovered by thinning cuttings and consequently included into the future multispecies stands, with Norway spruce share up to 30%.

Open access

Marcin Szydlarski, Jerzy Modrzyński, Mateusz Stopiński, Michał Majewski and Krzysztof Maras


The paper investigates the biometric characteristics natural Norway spruce (Picea abies (L.) Karst.) regeneration in the Kaszuby Lake District, which is beyond the acknowledged Norway spruce range, with the natural regeneration in the Augustów Forest situated deep within the natural range, Warmia, at the edge of the natural range and in the West-Pomerania Lake District far beyond the natural range.

For each region, four tree stands with similar light conditions on the forest floor were selected, including two cambisols and two brunic arenosols. All sites contained naturally regenerating spruces 16–17 years of age.

The features of the forest stand and the biometric features of the saplings were determined for the selected stands on circular research plots. Altogether, the characteristicts of 400 saplings (100 in each region) were measured and analyzed using basic descriptive statistics. ANOVA with the Tukey’s multiple comparison test was performed to compare the features of forest stands and the natural regeneration of spruce in each region. The degree of interrelation between regeneration features was described by Pearson’s, ‘r’ factor or Spearman’s rank correlation coefficient. A discriminatory analysis was carried out to determine the set of regeneration features differentiating regions from each other.

The features of regeneration that differed between regions the most were: height of regeneration, basal diameter, mean height increment, and mean basal diameter increment of the saplings. The parameters for Warmia and the West-Pomerania Lake District were similar. The Augustów Forest showed the lowest values for the regeneration parameters, while the Kaszuby Lake District produced the highest values. The regeneration in the Kaszuby Lake District was markedly different from all other regions as indicated by more dynamic growth. Additionally, this population shows a great distinctness, indicating adaptation to local environmental conditions, which may be proof for the insular presence hypothesis of spruce in this region.

Due to their good quality, spontaneously developing natural regenerations in the Kaszuby Lake District should be supported by appropriate cutting and silvicultural measures.