Species richness of drained riparian forests in the urban area of Wroclaw

Las Osobowicki forest is a remnant riparian woodland of the Odra valley, although its site conditions have been anthropogenically disturbed. To assess species richness of the drained forest, floristic data were collected from circular plots with a radius of 5.64 m. Plots were systematically distributed in forest communities. In total, 87 species were identified in the study area, with a mean of 14 species per plot. The share of alien species was minor. Flood prevention caused site drying and, as a result, decrease in species richness of the riparian forest. However, spatial distribution of species number values proves the sustained influence of the moisture factor on the vegetation. Connection of species richness and hydrological conditions is supported by positive correlation between species richness and Ellenberg moisture index

Increase of Cladonia species diversity as a consequence of clear-cutting in nutrient-poor forest sites

Clear−cutting impacts site conditions seriously. However, in nutrient−poor sites the effects of stand removal can be minor than in nutrient−rich sites. The aim of this work was to assess whether the clear−cut can improve species diversity of ground Cladonia species, which decline has been observed in forest communities. In stands of different age classes (≤10, 11−20, 21−40, 41−60, 61−80, ≥81 years) in the Przymuszewo Forest District (northern Poland) ground Cladonia species and their cover were recorded on research plots (10×15 m). A total of 24 species were identified in the study area. There were more Cladonia species and they were more abundant in young stands (<20 years old) than in stands older than 60 years. Nine species are significantly more frequent and demonstrated high fidelity in young stands and only one was characteristic for old stands. Composition of Cladonia species depended primarily on stand age and subsequently on canopy or bryophyte cover. In nutrient−poor sites clear−cutting is favourable for Cladonia species diversity

Diversity of vegetation in Scots pine monocultures on sandy soils in the Bory Tucholskie

Scots pine stands are the most important forest type in Poland and the differentiation of the natural vegetation in these forests is well known. However, the intensive utilization causes the formation of the secondary communities, so that further studies of the vegetation diversity should be carried out with taking into consideration stand age and homogeneity of site conditions. The aim of this work is to assess the diversification of plant communities across the gradient of tree stand age. Scots pine stands on oligotrophic sites of the Przymuszewo Forest District were examined with dividing into six age classes ( 10, 11−20, 21−40, 41−60, 61−80, 81−120 years old). Numerical analysis allowed to differ 4 plant communities: non−forest community of Placynthiella−Cladonia sp. div. related to young stands before crown closure ( 10 years old), secondary forest community of Pinus sylvestris−Cladonia subulata related to young stands just after crown closure (11−20 years), forest communities of Leucobryo−Pinetum variant with Cladonia and typical variant – both related to stands older than 20 years. The identified communities differ in terms of species richness and vertical structure, but they are repetitive combinations of species which can be classified within hierarchical syntaxonomical system. They show common features with the communities of south−western Poland, but differ from plant communities of managed Scots pine forest in the continental part

Vegetation diversity of the Scots pine stands in different forest sites in the Turawa Forest District

The utility of phytocenotic indices in the diagnosis and classification of forest sites might be limited because of vegetation degeneration in managed forests. However, even in secondary communities it may be possible to determine indicator species, although these may differ from typical and well known plant indicators. The aim of this work was to assess the vegetation diversity of Scots pine stands in representative forest site types along a moisture and fertility gradient. In total 120 sample plots from Turawa forests were included in the study. These plots represented young (21–40 years) and old (> 80 years) Scots-pine-dominated stands. The forest sites were categorized according to Polish site classification. Four site categories were studied: Boew (very nutrient-poor and mesic sites), BMoew (nutrient-poor and mesic sites), BMw (nutrient-poor and moist sites), LMw (quite nutrient-rich and moist sites). The species composition of the forest patches studied hardly differed among forest site types. Almost all of the vegetation in site Boew was different from both moist site types (BMw and LMw). Sites Boew andLMwhad the exclusive species determined as site indicators. Moreover, young stands had their own site type indicator species which differed from old stands. Numerical classification showed that only two plant communities were widespread: Leucobryo-Pinetum in Boew and BMoew, and the community of Pinus sylvestris and Molinia caerulea in BMoew, BMw, LMw. In secondary communities typical indicator species may not be useful, but it is possible to determinate species that are locally unique to forest site type. Despite the convergence in the composition of the plant community resulting from tree stand unification, plant communities have the capacity for a more diverse composition. Tree stand conversion can increase phytocenotic diversity

Flotistic and phytocenotic indicators of the conditions of riparian forests in the urban river valley

Urban river valleys are exposed to strong anthropogenic pressure, but despite these distortions they provide important habitats in urban areas. Not embanked forests are particularly valuable in urban river valleys as they represent fragments of natural vegetation in a highly changed environment. The study assesses the flora and structure of forest communities in a riparian urban forest complex that is under the direct influence of river water. Las Pilczycki Forest in Wrocław (SW Poland) is such a riparian forest island. We analysed the species richness and composition in terms of the phytocoenoses variability and their syntaxonomic classification. We also investigated if the vegetation can indicate a spatial differentiation in habitat conditions. Floristic and phytosociological data were collected from 70 circular plots (100 m&suo2; each) located in a grid. A total of 81 species were recorded, with a mean of 21 species per plot. Most frequent were: Acer campestre, Acer platanoides, Anemone nemorosa, Ficaria verna, Fraxinus excelsior, Galium aparine, Geum urbanum, Impatiens parviflora and Sambucus nigra. In biological spectrum the most numerous were hemicryptophytes, megaphanerophytes and geophytes. The number of alien species was minor (9% of the flora). The most frequent anthropophyte was Impatiens parviflora. Soil moisture, acidity and fertility indices exhibited spatial correlations and they were higher in the western part of the forest. The moisture index was also higher in the northern part. Species richness ranged from 13 to 32 (with a mean of 21 species). Two forms of Ficario−Ulmetum minoris were identified: with Galanthus nivalis and with Tilia cordata. The first was a well−structured riparian community, while the latter one represented the drained floodplain forest. Vegetation units are spatially separated, in the western part of the forest prevails form with Galanthus nivalis, while in the east – with Tilia cordata. In isolated alluvial forests of urban area local site conditions are crucial for the vegetation patches, because of the distortion of river valleys. The absence of flood embankments is not a sufficient condition for maintaining proper structure of riparian forests