Woodland vegetation can be restored via natural succession in sites that are adjacent to woods which can act as seed sources for trees, shrubs and woodland herbs. The influence of the dominant tree species, Scots pine Pinus sylvestris or black locust Robinia pseudacacia, and recreational disturbances on the floristic composition, species richness and spatial differentiation of communities that had developed in an abandoned sandy grassland over a 10-year period was studied in a suburban landscape in southern Poland. Data from 105 plots were used to determine the frequencies of various species groups and differences in soil conditions. Canonical correspondence analysis (CCA) and step-wise regression analyses showed that pine and black locust had a strong impact on the species composition of young woodland communities, and that human activity, in particular trampling, affected the spatial differentiation of vegetation. The total number of species, and the number and cover of trees, shrubs and woodland herb species, increased along an ecocline that has developed as a result of regular disturbances, whereas the number and cover of grassland species decreased. Cover of nitrophilous and ruderal species was most closely positively correlated with black locust cover; cover of heathland species with pine; and cover of woodland species with tree height. Grassland species were negatively correlated with tree height. Soils under young secondary woods were richer in P, NO 3 -N and NH 4 -N than in adjacent sandy grassland. Symbiotic nitrogen-fixation and the fast growth of black locust contributed to the increase in soil NH 4 -N. Differences in nitrogen availability and light conditions appeared to cause the strong divergence in the development of different types of young secondary woods. The species composition of secondary communities on poor sandy soils in a suburban landscape was thus indirectly determined by the dominant tree species, black locust or pine, and directly by recreational disturbances. Dispersal and colonization were important in determining which species of trees, shrubs and woodland herbs were present in a given site.

Effects of dominant trees and anthropogenic disturbances on species richness and floristic composition of secondary communities in southern Poland

1 Bialowieza Forest contains the most extensive stands of old-growth temperate woodland in Europe. It therefore has the potential to provide a model for near-natural woodland, which is a conservation aim for many sites in western Europe.



2 Pollen analyses from two small hollow sites in the northern part of Bialowieza Forest National Park are reported here. The records cover the last 1200–1500 years. The pollen data of the principal tree taxa were converted into vegetation data using previously published pollen:vegetation correction factors.



3 These data were used to reconstruct long-term vegetation dynamics in the Tilio–Carpinetum and Pino–Quercetum communities that dominate the forest. Changes in forest composition have occurred as a result of both autogenic and allogenic processes. High grazing intensities in recent centuries have been particularly significant, although the forest is often considered to be undisturbed.



4 The larger hollow (site I) initially sampled across Peucedano–Pinetum, Carici elongatae–Alnetum and Tilio–Carpinetum communities. Since 1750, the Peucedano–Pinetum community has dominated, but with an increased Picea component. This has recently been replaced by the Pino–Quercetum community following the reduction of grazing pressure. These recent changes are largely consistent with published successional models for Bialowieza Forest.



5 Site II recorded a relatively stable balance between the Tilio–Carpinetum and Pino–Quercetum communities until 750 years ago. The Tilio–Carpinetum community then expanded. The continued dominance of Quercus in this community is inconsistent with previous models.



6 The long time perspective available with pollen data permits the exploration of forest dynamics beyond the temporal range of existing models for Bialowieza Forest. Comparison of recent and older records revealed that anthropogenic impact on forest composition has been greatest in recent centuries.



7 This investigation highlights the significant role of history in determining forest stand structure and composition.

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2745.1998.00323.x

Reconstruction of long‐term successional dynamics of temperate woodland in Białowieża Forest, Poland

Eutrophication was recognized as a pollution problem in European and North American lakes and reservoirs in the mid-twentieth century. Since then, it has become more widespread. Surveys showed that most of the lakes in Asia, Europe, North America, South America, and Africa are found in eutrophic state. Eutrophication leads to significant changes in water quality. It lowers the value of surface waters for the industrial and recreational uses. The overpopulation of algae makes water unfit for swimming. The algae growing in long strands often twine around boat propellers and make boating difficult. Eutrophic waters tend to be scummy, cloudy, or even soupy green. The rapidly growing aquatic plants may wash onto the shores in storms or high winds, where these plants die, decay, and produce a bad smell all around such water bodies. The eutrophication in an aquatic ecosystem also causes significant changes in biodiversity. The eutrophication causes an increase in plant and animal biomass, frequency of algal blooms, growth of rooted plants, and decreases the species diversity. Due to eutrophication, an increase in turbidity and anoxic conditions occurs. Because of the high density of aquatic organisms in a eutrophic system, there is often a lot of competition for resources. This high degree of competition and high chemical or physical stress make the struggle for the survival in eutrophic systems higher. As a result the diversity of organisms is lower in eutrophic than in oligotrophic systems.

Eutrophication: Threat to Aquatic Ecosystems

The change in the species richness following a gradual invasion of Carpinus betulus in the patch of oak forest (Potentillo albae-Quercetum) in Bialowieza was studied between years 1980 and 1994. Species richness and species deletion were compared to the spatial variation in the density and size of C. betulus individuals. The study showed that, in a microscale, (1) the rate of deletion of heliophilous species was similar to that of shade-tolerant ones and was c. 2 species per 4 m2 per 10 years, (2) species richness was negatively correlated with the density and size of C. betulus saplings recruited to the shrub layer, (3) species deletion was positively correlated with the number of saplings in the shrub layer. The results support the hypothesis that the invasion of C. betulus is a proximate cause of the decline of Potentillo albae-Quercetum, and in a microscale, it has three stages: (a) initial colonisation of the ground layer by the seedlings, (b) recruitment of juveniles to the shrub layer, deterioration of light conditions and rapid deletion of species, and (c) closure of the canopy and deletion of remaining heliophilous species and vulnerable shade-tolerant species. Nomenclature: follows Ehrendorfer (1973) and Matuszkiewicz (1981).

Influence of the size and density of Carpinus betulus on the spatial distribution and rate of deletion of forest-floor species in thermophilous oak forest

The research was conducted in two natural forest communities: Potentillo albae-Quercetum (‘oak forest’) which allows much light to reach the forest floor and Tilio-Carpinetum typicum (‘hornbeam forest’) which shades the herb layer heavily. The seed banks were estimated from numbers of seedlings emerging from soil samples over one growing season. (1) Our results confirm the hypothesis that persistent seed banks are mainly formed by species with high light requirements. Of the species found predominantly in the seed bank and absent from the herb layer or occurring there very rarely in both communities 83% of species and 70% of seedlings were strongly light-demanding (Ellenberg's light index 6–9). However, the results do not support the hypothesis that seed banks in natural deciduous forest communities are small, poor in species and do not reflect the species composition of herb layer. (2) The seed banks of both communities were rich in species and relatively large. Species richness in the oak forest turned out to be higher than in the hornbeam forest (51 vs 45 species/2.4 m2), but size was smaller (2659 vs 5789 seedlings/2.4 m2). In the oak forest the most abundant species in the seed bank was Galium boreale, but it constituted only 19% of the total number of seedlings, whereas in the hornbearn forest the dominant species, Urtica dioica, constituted 57% of the total. (3) In each community the species composition of the seed bank and the herb layer was very similar (>70%). (4) The seed bank was more diverse in the oak forest than in the hornbeam forest (H′ 2.34 vs 1.68). (5) The seed banks of both communities differed in the contribution of species with varied light requirements; in the sunny oak forest species with high light requirements dominated, whereas in the shady hornbeam forest both strongly and moderately light-demanding species had similar contributions. Nomenclature: Follows Ehrendorfer (1973) and Matuszkiewicz (1981).

The size and diversity of the soil seed banks and the light requirements of the species in sunny and shady natural communities of the Białowieża Primeval Forest

Changes in littoral flora as well as aquatic and swamp vegetation were analysed with increasing eutrophication of the mesotrophic Lake Mikolajskie. Over 30 years the habitat conditions of the lake deteriorated and the phy-tolittoral was reduced from a zone 6 metres wide to one of only 2 metres. In addition, the number of submerged macrophyte species decreased by 50% and the frequency of most of the remaining species declined severalfold. No new species were encountered. Species retreating from the lake littoral included all Chara species, Potamogeton obtusifolius , P. natans and Hydrocharis morsus-ranae . A significant lowering of the phytosociological diversity and species richness of aquatic and swamp communities was observed. By 1994, six of the 12 associations identified in 1964 and representing the submerged and floating-leaved vegetation (e.g. Nitellopsidetum ubtusae , Charetum asperae and Potamogetonetum compressi ) were no longer present. In turn, 6 swamp communities from among the original 14 identified in the lake were lacking (e.g. Typhetum angustifoliae , Sugittario-Sparganietum emersi and Eleocharitetum palustris ). At the same time, two new aquatic and swamp communities appeared ( Ranunculetum circinuti , Myriophylletum spicati , Caricetum acutiformis and Caricetum distichae ). In contrast there was an increase in the species richness of reedswamp communities due to an influx of marshland species. While the 1990s witnessed a distinct decrease in concentrations of nutrients in Lake Mikolajskie, the consequent increase in water transparency was not associated with an increase in the area of submerged macrophytes, or the species richness of aquatic vegetation.

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Long-term changes in the flora and vegetation of Lake Mikołajskie (Poland) as a result of its eutrophication

The sample area of 2.8 ha, divided into 100 m 2 square quadrats, comprised two, distinguishable by traditional methods, oak forest patches and a fragment of a neighbouring mixed oak-hornbeam forest. The classification of quadrats was conducted by association analysis. Their identification and interpretation were performed on the basis of the systematic value and fraction of species of the characteristic oak forest combination in each distinguished quadrat group, as well as the range of distinguished communities. It appeared that due to the hornbeam invasion into the oak forest habitat, species forming the characteristic oak forest combination receded and the community area decreased. The data enabled reconstruction of the phases of oak forest recession. They corresponded to the successive phases of the encroachment of hornbeam undergrowth in the analysed area.

/pdf/changes-in-typological-and-spatial-boundaries-between-3oj27d35lf.pdf

Changes in typological and spatial boundaries between neighbouring communities of Potentitlo albae-Quercetum and Tilio-Carpinetum

This paper reports on the anthropogenic degradation of natural forest vegetation in Warsaw (Reserve Las Bielanski). The degree and form of degradation was assessed on the basis of composition and distribution of forest and non-forest coenoelements (sensu Walter & Straka 1970).

Barbara Solińska-Górnicka

Papers

Long-term changes in the flora and vegetation of Lake Mikołajskie (Poland) as a result of its eutrophication

Changes in typological and spatial boundaries between neighbouring communities of Potentitlo albae-Quercetum and Tilio-Carpinetum

Effect of a large city on the structure of coenoelements in a natural woodland in Warsaw