Resources of dead wood in the municipal forests in Warsaw

Dead wood plays an important role for the biodiversity of forest ecosystems and influences their proper development. This study assessed the amount of coarse woody debris in municipal forests in Warsaw (central Poland). Based on the forest site type, dominant tree species and age class, we stratified all complexes of the Warsaw urban forests in order to allocate 55 sample plots. For these plots, we determined the volume of dead wood including standing dead trees, coarse woody debris and broken branches as well as uprooted trees. We calculated the amount of dead wood in the distinguished site-species-age layers and for individual complexes. The volume of dead matter in municipal forests in Warsaw amounted to 38,761 m3, i.e. 13.7 m3/ha. The obtained results correspond to the current regulations concerning the amount of dead organic matter to be left in forests. Only in the Las Bielański complex (northern Warsaw) volume of dead wood is comparable to the level observed in Polish national parks or nature reserves, which is still far lower than the values found for natural forests. In general, municipal forests in Warsaw stand out positively in terms of dead wood quantity and a high degree of variation in the forms and dimensions of dead wood.Przemysław Szmi

Selected properties of organic soils under boreal mire spruce forest in the Romincka Forest, NE Poland

The paper presents selected properties of the organic soils developed in boreal mire spruce forests (Sphagno girensohnii-Piceetum) in the Romincka Forest (NE Poland). Additionally, the relationship between soil fertility and forest stand productivity was investigated. Data from 12 soil profiles, differing in terms of peatland ecological type (raised bog, transitional bog and fen) was used. The significance of the differences in soil properties among peatland types was assessed with the Kruskal-Wallis test. Soil fertility was described using soil trophic index (SIGo), whereas stand productivity according to site index (SI) value. The properties of the analysed soils varied significantly in terms of peatland type. Soils from fens were more fertile (SIGo 25–31), less acidic (pH > 5.7), with lower total potential acidity (36–40 cmol(+)·kg−1), higher base saturation (77–79%), Ca2+ content (116–136 cmol(+)·kg−1) and base exchange capacity (123–145 cmol(+)·kg−1) than soils from transition or raised bogs. No significant effect of soil fertility on the site index of stands growing on analysed soils was observed (r = 0.385, p = 0.216)

Impact of Tree Age and Size on Selected Properties of Black Locust (Robinia pseudoacacia L.) Wood

Black locust (Robinia pseudoacacia L.) is a non-native tree species that occupies a remarkable area in the forests of western Poland. It is mainly cultivated for the bee-keeping purposes as well as for its high quality wood. We investigated the impact of tree age and diameter on the selected structural, physical and mechanical attributes of wood of black locust that grows in conditions of mesic oligotrophic site. We analysed 200 samples originating from 18 trees that varied with age (38, 60 and 71 years old) and diameter (thin, medium and thick specimen selected according to Hartig’s method). Individual wood properties were determined along with corresponding European or Polish standards. Structural and mechanical attributes were determined for moisture of 12%. We found significant impact of tree age on tree-ring width, latewood proportion, density, oven-dry density, basic density, share of woody substance, porosity, as well as radial, tangential, longitudinal and volumetric shrinkage, compression strength parallel to grain, static bending, coefficient of compression strength parallel to grain and coefficient of static bending. The older the trees, the higher values of individual attributes were observed. In turn, the effect of tree diameter was less profound and no significant impact of that feature was found for latewood proportion, anisotropy and almost all of the shrinkage parameters. Thin trees exhibited the lowest values of the analysed parameters, while medium ones—the highest. In general, the highest technical quality of the investigated wood can be found in the youngest trees, whose wood characterises with the properties significantly exceeding native Polish tree species such as oak or beech

Slenderness of trees in black locust stands

This paper investigates the slenderness of black locust (Robinia pseudoacacia) trees in relation to the biosocial status of the trees, stand age class, crown parameters and habitat type. The research material was collected on 35 research plots in the Sława Śląska, Sulechów and Głogów forest districts in western Poland and comprises 1058 trees. For each tree, we measured height (h) as well as diameter at breast height (d) and determined its biosocial status (Kraft class), crown length (CL) and relative crown length (rCL). The age class and habitat type were assessed at the plot level. Because the obtained values for slenderness (s=h/d) diverged significantly from the normal distribution, we used Kruskal-Wallis and Mann-Whitney tests to investigate the influence of the above-mentioned parameters on the h/d ratio. Black locust slenderness ranged from 0.31 to 1.95 with an average of 0.91 (standard deviation 0.24). It furthermore differed significantly between Kraft classes (the higher the biosocial status, the lower the slenderness) and age classes (the older the trees, the lower their slenderness). We also found a significant effect of the habitat type (in oligotrophic sites trees formed more slender trunks than in mesotrophic sites) and crown parameters on the h/d ratio (decreasing with increasing crown length and relative crown length). The obtained results suggest that the slenderness of black locust does not differ substantially from native broadleaved trees in Poland

Assessments of diameter growth and optimal rotation length for even-aged spruce sites in Estonia

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Contrasting tree-ring growth response of Picea abies to climate variability in western and eastern Estonia

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Cyclic changes of climate in Europe during the last millenium according to dendrological data

The paper discusses periodic climate changes in Europe determined on the basis of dendrochronological data dating back one thousand years. In tree-ring width sequences of trees growing in Poland there are approximately 8-, 11-, 100- and 180- year periods. The tree-ring widths of oaks growing in Poland for the last centuries are characterised, without any significant amplitude, by 8- and 11-year periods (Tab. 1). In turn, chronologies of pine, spruce, larch, oak and fir growing in Europe are characterised by 100- and 180-year periods (Tab. 2). Cycles of dendrochronological variables approximate cycles of air temperature and North Atlantic Oscillation NAO as well as those of solar activity. The forecast of annual growth (ring width) for 2001-2100 was calculated by interference of the tree-ring width cycles determined by the sinusoidal regression method. Because of much longer empirical sequences of specific periods, the credibility of forecasts for treering widths is greater than that for air temperature