According to the results of many studies construction of dams, their decommissioning, and sediment flushing from the reservoir have been associated with vegetation dynamics. However, factors governing the spatial changes of forestation in the floodplain below the dams have not been explored extensively. This study examined the interacting effects of dam, inflow and land-use patterns of catchment areas and other factors on downstream vegetation patterns along the downstream reaches of Southern African Rivers. A total of 105 segments of 15 rivers (16 dams) located in seven Southern African countries were studied. Areas of herbaceous and forest vegetation of river channels below a dam and land-use catchment area patterns were obtained by the Google area calculator and aerial image analysis. Forest development was the highest just below the dams, and the ratio of forest cover decreased with distance from the dam toward the river mouth. Forest coverage ratio was found to decrease with an increase in dyke distance, number as well as of inflows (r = -0.66, P <0.01) and water coverage ratio, and bare land in the river flood plain. However, a principal component analysis (PCA) showed that the proportion of bare land in the catchment area, the dyke distance of the river and the number of inflows or tributaries are the factors most associated with forestation among the studied parameters. Forestation progressively decreased following the entrance of free following tributaries below dams, which appeared to reduce the effects produced by dams on vegetation forestation by causing local deviation. The impact of different land use types, such as agriculture on forestation, was insignificant though in some cases, land use areas cause the forest area reduction.

A set of medium-scale historical maps was used to reconstruct changes in spatial patterns of forest area during the last 220 years in an agricultural matrix of northeastern Europe (Zemgale region, Latvia). Changes in total forest area by soils were determined, as well as the time period of continuous forest cover. Proportion of protected area for each soil trophic group was also calculated. Patterns of recent forest development differed between soil trophic groups. Afforestation occurred mainly on wet and poor soils in the 19th and 20th centuries, while the proportion of woodland area on fertile soils typical for nemoral forests was fairly stable. Only 1% of the fertile soil area has been covered by continuous forest for more than 220 years, and only 11% of them are protected. Nemoral deciduous forests cover only 15% of their potential natural vegetation area of forested eutrophic soils. Therefore, in regard to habitat protection that is representative of natural distribution of ecosystems, priority in conservation should be given to forests on fertile soils.

It has been observed that leaf morphology shift within species is linked to climate change, but there are few studies on the effects of altitude change on leaf morphology of species. We hypothesized that similar to climate change, a morphological shift within species would occur over time under different growing altitudes. In this study, we evaluated three dominant grass species: Elymus nutans Griseb., Kobresia capillifolia Clarke., Carex moorcroftii Booth., taking advantage of the altitudinal variations (3000–4000 a.s.l.) on the Qinghai-Tibetan Plateau. Our study showed that almost all leaf traits of these three species had significant differences (P <0.05) across an altitudinal gradient. Different species responded differently to altitude change. Leaf thickness (LT) of the three species increased with increase in altitude. Leaf area (LA) of E. nutans and C. moorcroftii decreased with increasing altitude, but that of K. capillifolia increased. There was no obvious linear effect on leaf dry matter content (LDMC) and specific leaf area (SLA) of these three species. LDMC of E. nutans and C. moorcroftii showed a trend of increase, while that of K. capillifolia decreased. SLA of E. nutans and K. capillifolia showed a trend of increase, but that of C. moorcroftii decreased with increase in altitude. In addition, soil pH (pH) and air temperature (AT) decreased with increase in altitude. However, other soil and climate factors increased as altitude increased. The finding of this work is that leaf morphology shift within species happens under altitude change to adapt to specific environment.

Woodlands in different regions of Central Europe are mosaics diversified by floristic richness and age. The age of woodlands is understanded as the period of permanent existence of woodland phytocenosies, or at least a woodland site, without any transformations, even for a short period of time, to agricultural fields or any other areas managed in different ways. Forests which occur in identical habitats are often differentiated of their species richness. Data gathered from studies carried out to date, indicate that the age of a forest plays a significant role in the way plant communities develop. This relationship, however, is modified by a number of other factors.

In this paper, an attempt was made to answer the following questions: 1) are there any differences in this relationship between woodland age and richness, and species composition of recent and ancient forests, 2) does the age of a forest affect the richness of vascular plant species in the layers of their vertical structure, the number of species of various phytosociological groups, 3) which of the selected factors affecting the processes of migration and colonization, alongside age, affect the richness of species noted in forest communities.

The Ojców National Park (OPN) was chosen as a study area because its forests are diversified by age, from the younger than 71 to the older than 216 years and because the history of the forests there have been well documented. Age of selected woodland patches was determined using a ‘Map of distribution woodlands of different age in the Ojców National Park’, whereas the remaining factors were either measured or determined in the field or using available sources. In order to establish relationships, a multiple regression model was used.

The results obtained in the study prove that, in OPN, the age of the forest is the principal factor affecting the overall number of vascular species. Old forests are most abundant in species, and many plant taxa occur only in such forests. Within the same age classes, the number of taxa is often diversified because of the impact of habitat factors e.g., humidity, and it is also linked to the history of the development of these forests. The factors which affect the species richness in a particularly beneficial way is the presence of rocks, as well as the diverse relief of a given area. Much less significant are exposure and inclination of the terrain.

The age of a forest significantly affects the number of species in the herb layer, whereas it does not demonstrate significant correlations with respect to shrub or tree layers. The number of species in fertile deciduous forests are also positively affected, whereas no such relations were found in coniferous forest species. The results also indicate that the forest’s surface area, along with a specific combination of factors, may only have a limited effect on the richness of plant species in the area.

Increased nitrogen (N) and water availability, resulting from global changes or ecosystem management, were predicted to promote plant productivity and change community composition through shifts in competition hierarchies. So far, however, it still remains unclear how competitive interactions respond to N and water additions, which will be important to understand how plant community composition changes. To test plant competition ability in different successional stages under N and water addition treatments, a pot experiment under field conditions was performed. Six dominant plant species, three early-successional species, Artemisia lavandulaefolia, Artemisia capillaris, and Pennisetum centrasiaticum versus three late-successional species, Stipa krylovii, Leymus chinensis, and Artemisia frigida, were grown in monocultures and in twospecies mixtures under factorial combinations of N and water addition treatments. We found that (1) there were interactive effects of N addition, water addition and interspecific competition on plant biomass; (2) For a given species, competitive abilities were correlated with biomass difference of neighboring species; (3) N and water additions interactively increased competition intensity and shifted species competitive hierarchies; (4) Late-successional species had stronger competitive abilities in the N addition treatment, whereas early-successional species had stronger competitive abilities after water addition or N water addition. Our results show that N and water additions increased the intensity and impact of interspecific competition on plant growth, which has great implications for community structures. Since interspecific differences in competitive abilities were not well explained by species biomass, species identity, such as plant functional traits, should be included to predict the impact of increased N and water availability on plant communities and ecosystem functions.

The relationships of Hildenbrandia rivularis (Rhodophyta), the species composition of its surroundings detailed environmental variables (water chemistry and hydrological, morphological and bottom features) in a lowland river (Wełna river, Western Poland) was investigated. H. rivularis from 40 stands was tested together with 25 environmental variables and vegetation. Detrended correspondence analysis (DCA) and redundancy analysis (RDA) were used to describe the relations between the species composition and the selected variables. The uniqueness of this protected species is an ability of formation incrustation on rocks but also coexistence with two groups of species: other algae and vascular plants. In study twenty-two plant taxa were recorded in 40 vegetation plots, including 4 macroscopic algae, 2 mosses and 16 vascular plants. The most common H. rivularis co-occurred with Leptodictyum riparium, Fontinalis antipyretica and Nuphar lutea.

Most of the studied plots with red algae were characterised by shallow water and strong water velocity. H. rivularis prefers alkaline water with high conductivity. The results of the RDA, after forward selection, demonstrated that pH gradient, optical features such as dissolved organic matter and water colour — control the variation in the floristic communities with H. rivularis.

NOMENCLATURE: algae — AlgaeBase ( http://www.algaebase.org/, accessed August, 2013), mosses — Ochyra et al. (2003); vascular plants — Mirek et al. (2002).

The photosynthetic activity of phytoplankton (in pelagial) and macrophytes (in littoral) is considered to be one of the main factors affecting the carbon cycle in lakes. This concerns in particular hardwater ecosystems, where most of the carbon is available in the form of Ca- or Mg-bicarbonates. In such ecosystems charophytes (macroscopic green algae, forming dense meadows) are regarded as the most effective carbonate producer due to the HCO₃ — utilization and the formation of thick CaCO₃ encrustations.

Calcium carbonate and biomass production of charophytes were studied in a small and shallow charophyte-dominated Lake Jasne (Western Poland). Fresh and dry weight of plants, percentage contribution of calcium carbonate and production of CaCO₃ per 1 m² were studied at three depths (1, 3 and 5 m) in three sample sites (each sampled area — 0.04 m²). Additionally, physical-chemical parameters of water samples were studied. It was found that the dry weight of charophytes and the values of calcium carbonate were similar for all sites but varied for depth of sampling. The dry weight exceeded 2000 g m^-2 (average 1165 g m^-2) at the most shallow sample sites. CaCO₃ encrustations constituted from 39.5% at the depth of 5m, to over 82% of the charophyte dry weight at the depth of 1m. The maximum and average values of carbonates precipitated by charophytes were 1696 g m^-2 and 891 g m^-2, respectively, and exceeded results reported so far. The results of physical-chemical analyses revealed no statistically significant differences between all the sample sites. Nevertheless, distinct correlations were found between dry weight of charophytes, carbonates precipitated by charophytes and some physical-chemical properties of water from the sample sites.

The results highlight the habitat engineering role of charophytes, evidenced in particular by great amounts of biomass influencing sedimentary processes and biogeochemical cycle within littoral zone.

In stressful and harsh environments, safe sites for seedling recruitment may be created by nurse plants, which accumulate propagules and subsequently facilitate the establishment of individuals. The main goal of the presented studies focused on observations of seedling recruitment in small and large tussocks of Deschampsia caespitosa derived from patches of unmanaged Molinietum caeruleae meadows situated along the successional gradient and dominated by small meadow species (Patch I), by macroforbs (Patch II), or overgrown by trees and shrubs (Patch III).

The studies showed that, irrespective of patch character, Serratula tinctoria, Selinum carvifolia, Lysimachia vulgaris and Filipendula ulmaria are among the best colonizers of Deschampsia caespitosa tussocks. The gradual decrease in number of species and offspring abundance along the successional gradient may be connected with a prolonged period of water stagnation accelerating the development of fungal pathogens, a major cause of mortality for buried diaspores. The growing frequency of species present in standing vegetation and the gradually rising contribution of swamp and forest taxa in consecutive patches may be due to the production of non-persistent diaspores by early successional species, as well as reduced seed immigration from neighboring sites.

The obtained results included evidence that, regardless of patch character, the percentage of seedlings representing species present in and absent from existing vegetation as well as taxa with various vegetation types is similar in small and large tussocks. Furthermore, in small tussocks, regardless of patch character, anemochorous and hydrochorous taxa dominated, the frequency of endo- and epizoochorous taxa was much lower, while the percentage of species characterized by other modes of diaspore dispersal attained the lowest rates. In large tussocks, anemochorous and epizoochorous species prevailed, the share of endozoochorous and hydrochorous taxa was lower, and the contribution of species characterized by other modes of dissemination was very scarce.

On the basis of these studies it might be concluded that, despite the successive decrease of species and seedling abundance, and along with the increase in the recruitment of taxa resident in standing vegetation, especially woody species, the tussocks of Deschampsia caespitosa are reservoirs of meadow species even in advanced successional stages and may play a significant role in the process of long-term species turnover.

Parasitic plants are characterized by production of a large number, of one of the smallest seeds in the world's flora, of length less than 1 mm, frequently called ‘dust seeds’. The paper presents detailed data concerning the seed productivity and their size as well as morphological diversity of a very rare and endangered parasitic species Orobanche bartlingii (Orobanchaceae). O. bartlingii occurs from central and eastern Europe to China, although it is very rare and sporadic, totally absent in large parts of Europe. In Poland, O. bartlingii occurs mostly in the Silesia-Cracow Upland, sporadically in the Małopolska Upland and in the Noteć valley. Libanotis pyrenaica is the most frequently reported as the host plant of the Bartling's broomrape. O. bartlingii in Poland prefers thermophilous fringe vegetation of the Geranion sanguinei (Trifolio-Geranietea sanguinei class) and Prunetalia spinosae alliances (Rhamno-Prunetea class), xerothermic grasslands of the Festucetalia valesiacae order, usually with the saxicolous Festucetum pallentis association (Festuco-Brometea class). The studies were conducted at the most abundant population of the species in the Silesia-Cracow Upland (S Poland). The populations of species are located in the Podzamcze near Ogrodzieniec, on the highest elevation of the Silesia-Cracow Upland, the Janowski Mountain (515.5 m).

The working hypothesis of this study was that: (i) Orobanche bartlingii seeds coming from the same ovary differ in size and dimension, (ii) the slope exposure where Orobanche plants grew influences the seed productivity as well as some morphological traits. We examined the diversity of some morphological traits: the length of shoot (A) and corolla tube (B), the number of flowers per shoot (C). The aim of the studies was to show the seed dimensions and individual productivity, i.e. numbers of seeds per fruit (D), percentages of smaller seeds in ovaries (E), total number of seeds per plant (F). We also analyzed the data as well as the correlation between measured traits for all population and independently for plants growing on different slope exposure. The O. bartlingii seeds differ in terms of size and dimension. In each individual we found smaller oval seeds and bigger, more oblong ones. We state that the exposure does not have a significant impact on the (A, B, C, F traits) but individuals from N exposure featured a significantly lower percentage of smaller seeds in ovaries. We noted that more fertile individuals, i.e. those producing more seeds per individual contain smaller number of small seeds. The number of seeds per individual ranged from 1,870 to 627,250 with the coefficient of variation of about 99%. We found that higher individuals were characterized by a greater number of flowers, a higher seed production, a longer corolla tube and a higher number of seeds in the ovary no matter on which slope exposure they grew. Knowledge of the biology of endangered species, especially fertility and morphological diversity in microhabitat is essential for their protection.

Alder floodplain forests are a rare and threatened forest type in Europe. These forests can be very rich in mollusc species. The intermediate disturbance hypothesis predicts that species richness should peak at intermediate inundation frequency, that is, at intermediate elevation above the river level. We additionally hypothesized that constantly high soil moisture can distort the usually positive correlation between the amounts of downed deadwood and snail richness, and that tree stems might be more favourable than deadwood because their vertical structure provides a better refuge during inundation events. To this end, we sampled molluscs from a core area of 20 × 20 m from eight alluvial forests with black alder in the surroundings of Łódź, Central Poland. In each core area, substrate was collected from eight random plots (0.25 m² each). We also recorded soil pH, vascular plant species and mosses diversity, along with other structural variables. Plant indicator values were calculated according to Ellenberg. Soil quality (amongst others: soil pH, reactivity value, nutrient and moisture availability) decreased with increasing elevation above the river level. In the plot samples, we found a total of 18,497 individuals from 52 species. Mollusc species richness dropped stronger than densities with an increasing elevation above the river level. Main influences on mollusc richness and abundance originated from positive correlations with soil pH and moisture. An additional hand sampling campaign on tree stems and deadwood items in the core area revealed that coarse woody debris items on average carried twice as many individuals as did tree stems. Deadwood and tree stems supported similar numbers of snail species per item, but beta-diversity was higher on deadwood. Consequently, Jackknife 2 predicted that deadwood is utilized by about 46 species, whereas tree stems only support about 39 species. Our results indicate (1) that mollusc richness peaks at low elevations above normal water level in this type of forest, (2) that intact hydrological regimes are associated with high soil quality and mollusc biodiversity, and (3) suggest that coarse woody debris adds resources, refuges and a dispersal agent for the alder forest floor fauna.

Detailed knowledge of demographic parameters (such as age structure and reproduction rates) is crucial for guiding conservation and management decisions regarding wildlife populations. Such parameters of wild ring-necked pheasant populations in the current agricultural landscape remain very poorly described. We researched age structure and reproduction rates of predominantly wild populations of the ring-necked pheasant (Phasianus colchicus L.) across the intensively managed agricultural landscape of the Czech Republic. The study area is influenced only marginally by hand-reared pheasants (i.e. as shown by comparison of the average number of released individuals in the study area: 0.3 ♂/yr/1km² and 0.9 ♀/yr/1km² and average number of released individuals and harvested in the study area: 8.6 ♂/yr/1km²) and there is a long-term huntable pheasant population. To determine the age of individuals, we used proximal primary feather shaft diameters of 1487 feather samples from males hunted between 2009 and 2011. Moreover, we evaluated the age structure of females as well as both sexes together based on the sex ratio and annual game census. We found a relatively high proportion of adults in the population in comparison with other studies. However, the number of adults decreased throughout the years: 2009 (♂ 44.7%; ♀ 69.5%; ♂♀ 60.7%), 2010 (♂ 35.2%; ♀ 61.3%; ♂♀ 51.5%), 2011 (♂ 29.8%; ♀ 57.4%; ♂♀ 47.0%). The decrease of adults went hand in hand with increase of juveniles and reproduction rates of the study population: 2009 (♂ 124%; ♀ 44%; ♂♀ 65%), 2010 (♂ 184%; ♀ 63%; ♂♀ 94%), 2011 (♂ 236%; ♀ 74%; ♂♀ 113%). Only males were hunted in the study area so we determined higher proportions of females in population for all years. This is the main reason why the reproduction rate of females was lower in percentage expression. Generally, our results showed lower productivity of pheasants in the Czech agricultural landscape in comparison with earlier published studies conducted in the US and UK. However, these studies were published many years ago and thus do not reflect the actual environmental conditions and changes which took place recently (i.e. agricultural intensification).

Small solitary open nesting passerines, such is the Blackcap Sylvia atricapilla that builds nest in the undergrowth, have little chance of successfully scaring off a predator to defend a nest. The aim of our study was to determine if parental care by Blackcaps can reduce the risk of depredation of its nests. We compared the survival of natural clutches with artificial clutches (plasticine and independently both plasticine & quail eggs). The artificial clutch was placed in a nest after the natural clutch had been concluded, and the results were analysed as matched pairs of data. We assumed that significantly higher survival rates of natural clutches than of artificial clutches deprived of parental care, might indicate a significant positive effect of parental care on reducing depredation risk of Blackcap clutches. Losses caused by birds, rodents and larger mammals were 49%, 41% and 9%, respectively. The differences in survival rates of artificial clutches (plasticine as well as quail & plasticine) and natural clutches were not statistically significant. This might show that parental care is not strong enough to significantly reduce depredation risk of Blackcap clutches. Although this conclusion should be treated cautiously because it was difficult to assess the influence of using artificial clutches on our results.

Climate change is considered one of the greatest threats to biodiversity in future decades. Learning about the habitat preferences and geographical distributions of endangered species is critical for conservation management and planning in the context of climate change. This study investigated the effects of climate change on suitable habitat for Arborophila rufipectus Boulton, an endangered species that is endemic to southwest China. We used the known presence records for this species and a series of environmental variable layers to develop a predictive distribution model using maximum entropy modelling; this model was then used to assess the effects of future climate change on suitable habitat for this species. Our study indicated that climate change might have significant effects on suitable habitat for this species. By 2050, under a no-dispersal hypothesis, more than four-fifths of the habitat currently assessed as suitable would be lost, and the mean latitude of suitable habitat would shift northward by more than 100 kilometres. Based on this model, climate change would also aggravate habitat fragmentation. Under a full-dispersal hypothesis, all four climate trajectories developed by the Canadian Centre for Climate Modelling and Analysis (Ccma) and the Commonwealth Scientific and Industrial Research Organization (CSIRO) present similar trends: the area of suitable habitat is predicted to increase substantially, and habitat fragmentation would be mitigated under the two climate trajectories developed by the Goddard Institute for Space Studies (GISS). Finally, we offer some practical proposals for the future conservation of this endangered species.

Clutch size is an important life history trait in amphibians, and it varies among and within species, populations and individuals. Within a population, its variation has been attributed to a positive relationship between females' age or size and their fecundity as well as to spatiotemporal differences in environmental conditions. Therefore, clutch size has been shown to be both spatially and seasonally variable. We examined spatial and seasonal clutch size variation based upon two years of study involving 160 clutches of the Agile Frog Rana dalmatina Bonaparte, 1840 in 14 ponds within one spoil bank in the Czech Republic's North Bohemian brown coal basin. The overall mean clutch size was 1295 (SD 596), which is one of the largest that has been reported. However, both clutch size and its variance differed considerably between the years. Clutch size also varied among the ponds. We found no relationship between clutch size and the distance of a breeding pond from alluvial forest, a typical wintering habitat. Despite existence at the site of many suitable reproduction habitats, the spoil bank does not offer the complex of all habitats needed for persistence of the R. dalmatina population. To protect that population, it is necessary to preserve not only breeding ponds on the spoil bank but also alluvial forest and, most importantly, the connectivity between these two crucial habitats.

Diet of co-occurring Barn Owl and Spotted Eagle Owl has been studied by means of pellet contents analysis in urban and rural environments in the Highveld of South Africa. In urban environment, diet of both owl species was dominated by murid rodents (mainly Otomys, Mastomys and Rhabdomys). In rural environment, Barn Owl diet was also dominated by murid rodents, but in the diet of the Spotted Eagle Owl higher proportion of birds and non-murid rodents was recorded. Although in the rural environment the breadth of diet niche was wider in Spotted Eagle Owl (DB = 35.41) than in Barn Owl (DB = 12.67), there was almost total dietary overlap (DO = 0.98) between these two co-occurring owl species. For contrast, there was only slight food niche overlap (DO = 0.12) between these owl species co-occurring in the urban environment, but the diet breadth here was also wider in Spotted Eagle Owl (DB = 29.02) than in Barn Owl (DB = 17.90). In the urban environment diet breadth of the Spotted Eagle Owl is, therefore, slightly wider than in rural environment, while in the case of the Barn Owl the reverse is true. Probably there is lower abundance of available prey in urban and rural areas in the Highveld, in comparison with more natural habitats. This may force both species to resort to a more diverse diet to meet their energy requirements. Both species show, therefore, high plasticity of foraging.

Early post-fledging mortality of White Stork during the period from the first flight to their autumn departure from natal area was described. Data from eight breeding seasons (2005–2012) about 56 cases of death of juvenile White Storks from a study area in Western Poland were collected. For a comparison the data of 55 cases of death from recoveries data deposited in Polish Bird Ringing Centre from entire Poland were included in analysis. Early post-fledgling mortality rate varied from 2 to 11% (mean 4.3%) of all fledglings per year. The main causes of death were collision with power lines and electrocution which in Western Poland constituted 60% and in entire Poland — 78% of death cases with known causes. Other anthropogenic causes constituted responsibly 25 and 13% and natural causes — 15 and 9%. Mean distance where dead storks were found was 183.3m from natal nests, while 73% were found closer than 100 m from their nests.

Habitat edges are regarded as important components of heterogeneous landscapes. Diverse theories exist about the diversity and functional role of edges, and no generalisation have been possible so far, thus case studies are important for better understanding the landscape scale processes. Forest management highly modified the structure and tree species composition of the European forests. The sylvicultural intensification resulted in the rise of the proportion of non-native, intensively managed forest stands. In the present study we explore the response of spider and ant assemblages to forest stand type and the edge effect between native poplar and nonnative conifer plantations in Hungary. We applied pitfall traps to sample the ground-dwelling spiders and ants. Four plots consisting of the two forest types and the transition zones between them were selected. Five transects for each replicated plot were sampled. We identified the significant indicator species of the different habitat types. We found significant differences in the species richness (i.e. number of species) of ants and spiders of the different habitat types. We detected intermediate spider species richness at the edge indicating that edges separate a higher quality habitat from one that has lower resource quality; however, the species richness of ants was the highest at the edge and did not differ between the two forest types. The positive impacts of edge was found due to presence of generalist and grassland species at the edge and presumably edges separate patches that provide complementary resources also increasing the number of ant species.

Our results indicate that forest type affects the species compositions of ground-dwelling spiders and ants. Our study also shows that habitat type had a major effect on the species richness and composition of spider and ant assemblages, suggesting that local forestry management plays a crucial role in preserving the native invertebrate fauna of forests.

Trichocerca simoneae De Smet described in 1989 has since been found in tropical and subtropical areas, but was not recorded in Poland before World War II. A bibliography of Polish rotifers by Wiszniewski (1953), although very comprehensive, does not refer to T. simoneae. However, in the studies of plankton of the dystrophic lake, i.e. humic one with water rich in humic acids, acidic pH and brown coloured, carried out in the years 1998–2000, the species dominated. Here, studies in 39 small, inter-forest lakes of north-eastern Poland revealed T. simoneae in 15 of them, often at high densities, up to ca 6000 ind L^-1. The possible reasons for this ‘invasion’ are: (1) zooplankton communities in dystrophic lakes are unsaturated with biotic interactions too weak to exclude invaders; CCA and RDA analyses showed that T. simoneae preferred habitats with low number of zooplankton species of low density and dystrophic lakes seem to offer such habitats; (2) long-term deposition of rotifer resting eggs is probably more successful in sediments decaying at low rates. The latter possibility seems to be confirmed by observed in the littoral zone of dystrophic lakes appearance from time to time, of rare, mostly tropical species of Rotifera (e.g., Lecane hornemnni, L. monostyla, L. sola).