Phytosociological Data in Assessment of Anthropogenic Changes in Vegetation of Rzeszów Reservoir

Phytosociological research on aquatic and marsh vegetation was conducted in Rzeszów Reservoir (SE Poland): 134 relevés according to the Braun-Blanquet method were collected there in 2016 and compared to 91 relevés published in 1994 (225 relevés in total). Changes in vegetation type, diversity measures, species composition, and Ellenberg Indicator Values (EIVs) for light, moisture, reaction, and nitrogen were analysed. Over the 22 years (1994–2016), the greatest changes were noted in communities of the classes Lemnetea and Potametea and the alliance Salicion albae. The long-term observations demonstrated the disappearance of 14 phytocoenoses and the occurrence of 12 new ones. An expansion of marsh communities (Typhetum latifoliae, Typhetum angustifoliae, Glycerietum maximae, Leersietum oryzoidis) was noted, causing a decline of several species and vegetation types. According to canonical correspondence analysis (CCA), four environmental variables (light, moisture, nitrogen, and pH) were related to plant distribution. The strong disturbances reflected in intensive eutrophication were due to human activity, which is the main factor shaping the ecological succession and overgrowing of the reservoir.

Fifteen years of habitat, floristic and vegetation change on a pioneer sand-dune and slack system at Ainsdale, north Merseyside, UK

Changes in habitat, floristics and vegetation between 2005 and 2019 were studied on 2.9 ha of sandy foreshore near Ainsdale-on-Sea, north Merseyside. Named the ‘New Green Beach’, the site initially supported saltmarsh vegetation but, within five years, a 30-35 m-wide embryo dune ridge had formed, eventually 3.5 m high, backed by a 300 x 30 m seasonally flooded, calcareous dune-slack. The latter was colonised by pioneer slack plants, after which it rapidly developed areas of tall-herb fen and Alnus/Salix carr, while saltmarsh plants declined. During succession, species recorded as ‘rare’ became fewer in number while a higher frequency of ‘abundant’ taxa was recorded. The number of vascular plants listed annually increased from one in 2005 to 154 in 2019, though the rate of addition of new plants fell after 2010. Overall, 246 taxa were identified during the study. Only 9% of these were non-native, 17% being regionally or nationally notable, including 16 Red-listed species. Very poor statistical fits were obtained to recognised UK National Vegetation Classification vegetation types. Analysis of Ellenberg Indicator Values for salinity, nitrogen, moisture and reaction showed that the plant community became progressively adapted to low salinity, lower fertility, drier conditions and a less basic soil. The findings are discussed in relation to comparable studies elsewhere in Britain and Northern Europe. The rate of succession on the New Green Beach seems remarkably high, while evidence of declining soil fertility over time was unexpected.

Changes in the Diversity of Dry Calcareous Grasslands After Abandonment of Traditional Management in Devínska Kobyla National Nature Reserve (Southwestern Slovakia, Central Europe)

This study is focused on the evaluation of the values of the diversity indices of semi-natural dry calcareous grasslands of the Festuco-Brometea class in the area of Devínska Kobyla National Nature Reserve 50 years after abandonment of traditional management (grazing and mowing). The values of the species richness, the Shannon–Wiener index of diversity, the Simpson index, and Pielou’s measure of species evenness in the communities in the old and recent data, and the values of the environmental variables based on the Ellenberg indicator values of species were analyzed. For most of these analyses, we used Kruskal–Wallis in R 3.5.1. Compared to the past, we have recorded a significant lower values of the species richness, biodiversity, and species evenness in some communities. In some communities, no significant changes were recorded. Only in one community—Poo badensis-Festucetum pallentis, the higher values of Shannon–Wiener index was recorded compared to the past. The analysis of the Ellenberg indicator values revealed a statistically significant higher Ellenberg indicator values for moisture and nutrients and lower values for light in more recent period compared to the old period. The recorded results could be caused by the changes in the management after the year 1965, after abandonment of grazing and the gradual overgrowing by woody species took place in the area. The frequency of occurrence of some woody species (e.g., Populus alba, P. nigra, and Robinia pseudoacacia) in some communities increased compared to the past.

Impact of Short-Term Abandonment on the Structure and Functions of Semi-Natural Dry Grasslands

A study of the impact of short-term abandonment on the structure and functions of semi-natural dry grasslands in Lithuania was performed. Data on the abundance of vascular plant species, hay and litter samples were collected. At the same time, plant functional traits and Ellenberg indicator values were used to evaluate the effect of abandonment on the structure and functions of semi-natural dry grasslands. The results showed that litter layer was significantly heavier in unmanaged plots compared to that in managed plots. The vascular plant species pool was higher in managed plots, where 62 vascular plant species were identified, while in unmanaged plots 46 species were identified. The species richness was significantly higher in managed semi-natural dry grasslands. Unmanaged plots had 12.3 ± 0.6 species, while managed plots had 17.7 ± 1.2 species per one square metre. Functional plant traits were similar in mowed and abandoned communities, while functional diversity was lower in unmanaged communities. These results are a clear indicator that the managing of semi-natural dry grasslands creates heterogeneity of the environment.