The surface water microlayer (SML) is a thin layer found at the interface of the hydrosphere and the atmosphere. It is capable of accumulating chemical substances and microorganisms at a rate as high as 100-fold greater than that observed in the subsurface water. The rate of accumulation of biogens and chlorophyll a in SML of an estuary, where marine and fresh waters mix, varies considerably and it depends on the degree mixing of these waters, which is manifested in the varying values of the enrichment factor (EF, calculated as the ratio of nutrients concentration in SML versus subsurface water). The influence of the Baltic Sea marine water and the freshwater Łeba River inflows on the estuarine Lake Łebsko (Poland) was examined. Nine sampling sites were located in the estuary. Water samples were collected from two layers: the surface microlayer (thickness 242 µm ± 40) and the subsurface water (15 cm depth). The capacity of the SML to enrich the water in nutrients and chlorophyll differed among various parts of the estuary, as well as between seawater and river waters. Statistically significant higher EF were found in the marine waters than in river waters for the nitrogen and phosphorus compounds as well as chlorophyll. There were also differences in EF between marine and lake waters. The highest EF were also recorded for organic forms of nitrogen and phosphorus in marine water. Most probably, marine flux into the estuarine Lake Łebsko, resulted in the increased EF for these investigated components.

Coastal wetlands are ecologically important all over the world, and they are relatively unstable with dramatic changes in aboveground vegetation. However, it is still unclear how the aboveground vegetation changes will influence the functioning of coastal wetland ecosystems, especially the decomposition processes. Here, we carried out a cotton strip experiment to examine the effects of Suaeda salsa community on the soil properties and the associated cellulose decomposition rates in the coastal wetlands of Liao River delta (NE China). Our results showed that S. salsa community significantly affected the contents of soil C, N, P, base cations, organic matter and the soil electrical conductivity (EC), and such effects might vary among different types or densities of aboveground vegetation. The soil cellulose decomposition rate (in terms of cotton strip tensile strength loss, CTSL) was slowed down when aboveground S. salsa communities are experiencing degradation or have been totally replaced by Phragmites australis communities. Moreover, there were positive partial correlations between soil N and CTSL, and between soil EC and CTSL, but a negative partial correlation between soil C and CTSL. Our results emphasized the importance of S. salsa community in determining the soil cellulose decomposition rate in this coastal region. The results suggest that vegetation degradation in coastal wetlands might lead to various changes in soil properties and hence affect other aspects of ecosystem functioning and services, especially nutrient cycling.

The main aim of this study is to present the role of anthropogenic habitats created by the remnants of old iron ore mining activities in preserving the ancient woodland plant species (AWS). The studies, which took place in 2010–2015, covered 30 former post-mining fields in the northern foreland of the Świętokrzyskie Mountains (SE Poland). Each field contains the remnants of old iron ore mining – gob piles and the areas not transformed by mining, which surround the heaps. Within each post-mining fields, two lists (on gob piles and in their surroundings) covering the AWS were prepared. Additionally, two substrate samples were taken – one from the randomly selected gob pile, and one from the non-transformed site. The relationships between the numbers of AWS and selected environmental variables were analysed by statistical methods. It was found that the difference in the number of AWS characteristic of the Querco-Fagetea class between gob piles and their surroundings is significant. The conducted analyses indicated that this difference is not resulting from the difference in the areas between gob piles and their surroundings but from the pH of the substrate. The numbers of the mesophilous AWS in gob piles are not uniform and range from 3 to 37 and are correlated with the age of gob piles, the pH values and the depth of the iron ore deposits. At present, the remnants of old ore mining – gob piles constitute the sole habitat islands for the ancient mesophilous deciduous woodland species within the northern foreland of the Świętokrzyskie Mts.

Edge to interior gradients in forest ecosystems can influence the species composition and community structure as a result of variations in micro-environment. In this study, the edge effects on stand productivity and plant species diversity were investigated in two adjacent types of forests in central-southern China: Chinese fir adjacent with pine forests and Chinese fir adjacent with broad-leaved forests. A total of 48 sample plots for overstory and 240 sample quadrates for understory in different stand ages were set up. The tree growth parameters were measured in the overstory while the plant species diversity was measured in both overstory and understory of the examined forests. The results showed that DBH (tree diameter at the breast height), tree height and stand volume in overstory increased from the central areas (CA) of forests to the edge areas (EA), and the plant species richness and diversity in understory were greater in EA than in CA. The edge effect was greater in Chinese fir paired with broad-leaved forests than in Chinese fir paired with pine forests. The edge effect decreased in an order as young aged stands > middle aged stands > mature aged stands in the studied forests. The changes in tree growth and species diversity in the edge area compared to the interior were mainly attributed to the alteration of micro-environmental factors such as light density, temperature and moisture. Our results suggest increasing forest productivity and plant species diversity could be achieved by making more edges in the forests.

The white stork Ciconia ciconia is a typical open-area species, foraging mainly in farmland and wetland areas. The main aim of this paper was to describe the foraging ecology of white storks inside un-typical habitat, i.e. forests in Poland. Data on white stork feeding in forests were based on responses to questionnaires distributed to several national mailing lists with a total of 1700 (16% subscribers) and via emails to naturalists (mainly to white stork researchers). In total 63 observations, from the years 2000–2015, were collected, mainly from eastern Poland. In all cases, only a single adult individual was recorded inside the forest, with a mean (±SD) distance to the forest edge of 50 ± 102 m (n = 597) and 1315 ± 1015 m (n = 63) to the nearest white stork nest. Birds foraging inside forests were recorded from late May to mid-August, but the greatest numbers were seen during June. The main prey was a lizard, the slow-worm Anguis fragilis, with a maximum of 10 individuals collected by a stork during one foraging session. We discuss the origin of the observed foraging behaviour, noting that the species is flexible and opportunistic in terms of consumed food. The observed foraging is probably similar to the original behaviour of the species within primeval forest, although food opportunism helps the white stork to use new foraging areas, for example landfills.

Although freshwater habitats play a crucial role in most ecosystems in the world, little is known on their functioning in tropical regions even in regard to the most often studied avian communities. In this study, counts on waterbirds were conducted in dry and wet season (in years 2001–2008) in a riverine habitat in southern Africa (Shamvura stretch of the Okavango River). In total, 84 waterfowl species were recorded. The birds were assigned to different guilds according to their migration activity, diet and nesting site selection. In overall, the species number was almost the same (74 vs. 73) in the wet and dry season. The abundance of all resident species recorded was lower in wet (N = 5992) than in dry seasons (N = 6965)(χ² = 73.1, P < 0.01). In both seasons Palearctic migrants were represented by seven species, which comprised 1–2% of all waterbirds. Six species were classified as dominants: African reed cormorant Phalacrocorax africanus, African openbill stork Anastomus lamelligerus, cattle egret Bubulcus ibis, wattled lapwing Vanellus senegallus, African darter Anhinga rufa and white-faced duck Dendrocygna viduata. In the wet season the dominant species comprised 68%, while in dry season – 52.5% of all birds recorded. Significant seasonal differences in the numbers of individuals were shown for the following species: African reed cormorant, great egret, squacco heron, wattled lapwing and pied kingfisher. Insectivorous and omnivorous birds were more abundant in wet season, while piscivorous, carnivorous and plant eating birds in dry season. These differences can be related mainly to seasonal variation in the availability of food as well as to the timing of breeding.

The impact of the European beaver Castor fiber on deadwood resources near dams on the rivers of Wigry National Park (northeastern Poland) has been analyzed. The river sampling area was subdivided into the flooded zone, scarp and upland.

We found that beaver feeding was limited to the flooded zone and the scarp. Within a distance of 40 m of the river, beavers browsed 75% of all deadwood pieces (wood debris, stumps, dead trees). The wood generated via direct browsing by beavers made up 5% (3.29 m³/ha) of the total wood volume and 35% (641 pieces/ha) of the total number of wood pieces in this region. The beavers mostly left small pieces of wood (with a mean diameter of about 4 cm) at an area after feeding. The deadwood volume and number of pieces were significantly different in front and behind the dam only in the flooded zone. The volume of deadwood in front of the dam in the flooded zone was higher by 65% than behind the dam (102 and 62 m³/ha, respectively), and the number of pieces was higher by 75% (2200 and 1200 pieces/ha, respectively).

We prove that beavers generate the majority of dead wood indirectly – by flooding a part of the area. This results leads to conclusion that frequent flooding of a given area may lead to limiting the source of deadwood in the long term. We also confirm that through direct browsing, beavers produce small amounts of thin dead wood with less usefulness for other groups of animals, thus in this way beavers are not able to provide high-quality deadwood resources.

In this study, generic composition of food and foraging preferences of the European beaver were determined on sites where the beavers were reintroduced after more than 200 years of absence. Research area was located on lowland (Silesian Lowland) and highland habitats (Bystrzyckie Mountains, Wałbrzyskie Mountains) in western Poland. During the study period, 17,418 trees and shrubs growing within the feeding area of the beavers were marked, out of which 4,669 were found to be cut by beavers. The results showed that the foraging preferences of beavers depend on the availability and diversity of the local food sources. In the lowlands beavers preferred the following species of trees and shrubs as their primary food source: Salix cinerea, S. fragilis, S. caprea, Cornus sanguinea and Populus tremula. In the highlands, beavers preferred Corylus avellana, Sorbus aucuparia, and Fagus sylvatica due to the low availability of Salix and Populus species. Moreover, in the highlands, beavers had to cover longer distances to reach the feeding sites and had to cut trees with larger diameter than in the lowlands.

The research conducted in settling ponds located in the coal basin in Upper Silesia (southern Poland), detected in one of them presence of the widgeon grass Ruppia maritima. Currently, it is the only inland site of this species in Poland. The widgeon grass creates underwater meadows in the shore zone of the settling pond and it grows in dense communities together with the common reed Phragmites australis in the coastal zone. Apart from these two plants, no other species were found. The morphological features of the vegetative and generative organs of the studied population of R. maritima is similar to those that have been reported from Europe. The bottom of the pond is atypical for R. maritima – it is covered by mine waste. The water of the settling pond has a high salinity and the water chemistry corresponds to the more natural environments that are inhabited by widgeon grass. This substitute habitat, which imitates the natural environment of R. maritima contributes to the good development of these species. However the studied settling pond offers unstable conditions due to the ongoing mining activity and requires permanent monitoring.

The effect of urbanisation on parasite prevalence, especially these associated with human diseases, such as Lyme borreliosis, is of high interest. The blackbird Turdus merula is a ground-feeding species particularly predisposed to constitute a Borreliella spp. (Lyme borreliosis causative agent) reservoir. So, the aim of the study was to examine if the tick infestation level and their Borreliella spp. infection prevalence differs in blackbirds resident in two disparate habitats in Poland – one highly urbanized (in Warsaw agglomeration) and the other forested (in Mazurian Lake region). The infection in ticks feeding on blackbirds was ascertained based on detection of bacterium DNA (PCR). The prevalence of tick infestation in urban and forest-living blackbirds was similar (90 and 91.7%, respectively) but the mean number of parasites per bird was markedly greater in the forest (4.0 ind.) than in the urban populations (1.5 ind.). Even though, the Borreliella spp. infection of the ticks was significantly greater in the urban (46.7%) than in forest habitat (35.4%). Additionally, in the urban site more birds carry at least one infected tick than in the forest. The results of the study seem to confirm the role of blackbirds in establishing Borreliella spp. reservoir. Special regard should be given to highly urbanized areas, where the relative increase in the relevance of birds as tick hosts and pathogen transmitters may pose high risk to public health. Thus, the study constitutes a small-scale but an important contribution to our understanding of the role of birds in maintenance of Borreliella spp. foci in urban habitats.