Ontogenetic structure of populations of forest-forming species of the Left-Bank Polissya of Ukraine

The results of study of the population ontogenetic structure of the main forest-forming species (Pinus sylvestris, Quercus robur, Acer platanoides, Betula pendula, Populus tremula) of the Left Bank Polissia of Ukraine are presented. The study covered plant communities, which are the most common and typical in the region. They are represented by four formations of forest vegetation, viz. Pineta sylvestris, Querceta roboris, Betuleta pendulae, Populeta tremulae, and belonged to 24 syntaxes in the rank of association groups and up to 42 syn-taxons in the rank of associations. The study was based on the use of geobotanical and population-ontogenetic approaches and methods. It was established that in the forests of the region, the most part of main forest-forming species populations have left-sided ontogenetic spectrum. Invasive populations are the predominant category. Only in the populations of the species involved in the formation of the second and especially the first tier of stands reveals the centred and bimodal spectra. In these species, the frequency of normal population occurrence increased, but their proportion was within 6.7–13.6%. No regressive populations were found in the main forest-forming species of the region. It was fixed that the ontogenetic spectra of the most of populations of the studied species were incomplete due to the absence of plants of some ontogenetic states. It was noted that the individual extinction of the young generation before they reached the generative ontogenetic state, was the clear evidence of significant disturbance in the region forests of the generation variability in forest-forming species. The limited representation of windfall microsite complexes in the composition of the forest plant communities of the Left-Bank Polissia of Ukraine as well as gaps enough in size to ensure successful undergrowth development and formation of a continuous flow of generations is one of the consequences of long-term man-made impact on these forests. Keywords: forest phytocoenosis, forest-forming tree species, population analysis, population structure, ontogenetic spectrum, Polissia of Ukraine

Effect of black walnut (Juglans nigra) on the understorey vegetation – a case study of South Moravian forests (Czech Republic)

The article analyses the influence of black walnut on forest phytocoenosis in South Moravian forests and assesses how its representation may affect the understorey vegetation of the forest ecosystems. In July 2014, 31 relevés were processed in the South Moravian forests. These were stands of pure black walnut (Juglans nigra) as well as black walnut with small-leaved lime (Tilia cordata), along with neighbouring autochthonous stands (pure ash – European and narrow-leaved), oak (summer oak), or their mixtures. Ellenberg’s indicator values reveal differences in the plant communities under black walnut comparing those under native tree species for the variables nitrogen, soil reaction and temperature. In addition, total cover is significantly higher under walnut. Other differences are visible from the detrended correspondence analysis ordination. The study also confirmed that in the stands of black walnut the preference of some species is suppressed, for example Brachypodium sylvaticum and Poa nemoralis in alluvial forests and Melica uniflora in hilly forests.

Viscario vulgaris-Quercetum petraeae Stöcker (1965) in the Opawskie Mts (Eastern Sudetes)

Results of phytosociological studies conducted in the southern part of Opole Silesia within the Sudetes mountain range in 2014-2015 are presented. The main aim of our research was to confirm the occurrence of Viscario vulgaris-Quercetum petraeae Stöcker 1965, which had previously been noted in Poland only within the Central Sudetes Foothills in Lower Silesia province. Two additional sites of this extremely rare in Poland plant association were confirmed, located within the Opawskie Mts in Opole province. The association develops on steep slopes, near rocky outcrops, on southern or western expositions at altitudes between 350 and 410 m a.s.l. All plots of the association consists of several diagnostic taxa and the share of thermophilous plants is clear. The Viscario vulgaris-Quercetum petraeae is rather species poor forest phytocoenosis with the herb layer abundance shrink by a scree downslides. The most frequent taxa contributing to the sampled plots were: Luzula luzuloides, Galeopsis ladanum, Hieracium laevigatum, Lembotropis nigricans, Vaccinium myrtillus, Deschampsia flexuosa and Viscaria vulgaris. In all forest plots the Quercus petraea apparently dominates and shrub layer is scarce.

The dynamics of bodícka brána forest vegetation

This article presents evaluation of long-term (1990–2004) stationary research on a forest phytocoenosis with the dominant tree species Populus × canadensis in the area affected by hydropower water structures Gabčíkovo on the Danube river. In the first three years of monitoring, where natural flooding occurred, species diversity was low, the structure and ecological proportion of a phytocoenosis were stabilized in an observed adult stand in rotation age. After clear-cutting and reforestation all the indicators changed (trends of parameters were statistically tested). An average of diversity increased 2.5 times, an intensive plants turnover was continuing during two years, and there was quantity of spreading of synanthrophyte, helipohyte, and nitrophilous herbs (species). After oscillating of ecological parameters (light, temperature, continentality, soil moisture, soil reaction, soil nitrogen), like forms and the species diversity were decreased in indicators, as well as a decline of heliophyte, synanthrophyte, and nitrophilous species. Formation of vegetation after 6 years of reforestation gradually tends to reach the state in the 90s. A tree layer was formed and herb understory was growing in mosaic.