Competition among trees is a fundamental interaction process within plant community, which is the theoretical basis of thinning. Plant competitive intensity is generally measured using a competition index (CI) that can be classified into two major categories: distance-independent and distance-dependent. The current study used Cunninghamia lanceolata (Lamb.) Hook as the test subject and used Hegyi's CI (distance-dependent), to quantify individual CI and their relationship with tree diameter at breast height (DBH). Five different criteria were used to select potential competitors for the calculation of CI. Seven basic linear and nonlinear mathematical functions were used to test and quantify the relationships between DBH of the target tree and the individual CI. Results showed that individual CI was negatively correlated with target tree DBH: as DBH increased, competition intensity weakened. The adjusted R² with five different criteria of selection competitors simulated by seven functions ranged from 0.30 to 0.82. Considering the root mean square error (RMSE), P-value, and adjusted-R², our results suggested that the best model to simulate the relationship between individual CI and focal tree DBH was power function (CI = 43.98 × DBH^-1.08, adjusted R² = 0.81) and with the Voronoi diagram method as the criteria for selecting competitors. These results can demonstrate a clearer understanding of the spatial structure of forests, and can be used to guide the selection of thinning trees in the process of thinning practice.

There is little consistent evidence for evolutionary associations from seed production to seedling fitness. In this study, 20 species of Rhododendron genus were selected from subtropical forests of southwest China; the life-history functional traits such as the seed size, seed number per twig, germination traits, dispersal and seedling survival were investigated, the ecological relationships among them were tested and the advantages of small-seeded species were discussed. The results show that the quantitative parameters of germination, such as the germination rate, potential, and index are positively correlated with seed number produced per stem, while temporal parameters, such as germination peak timing and duration are positively correlated with seed size. The two results indicate that different Rhododendron species with different seed sizes and relative seed number can deal with varying environments according to spatial dispersal or time dispersal, respectively, and the advantages of smaller seeds in the aspect of sprouting vigour, dispersal ability and seedling survival may lay the foundation for the establishment of small-seeded plants in the forest.

Using multiple classification approach to examine plant traits response to grazing and fencing (as without access to grazing) is rare. Here we used multiple classification approach to examine plant diversity, productivity and species traits response to grazing and fencing over a three-year period on the eastern part of the Qing-Hai Tibetan Plateau. The results showed that most common species response to the fence was poorly noticeable. The fencing meadows compared to those under long-term free grazing are characterized by significantly higher total species richness, but species richness declined with sampling years gradually, regardless of grazing or fencing. The correlation showed that species richness was negatively associated with mean annual temperature significantly, suggesting that abiotic factors (e.g. annual temperature) could also play important roles in driving species richness in this subalpine meadow. Total aboveground biomass was not associated with mean annual temperature and rainfall. The fencing meadow demonstrated higher community aboveground biomass relative to the grazing ones, especially the abundance of legume and graminoids increased, while the proportions of sedge decreased, suggested that grazing disturbance favours the increase of reproductive success of sedge (e.g. Kobresia humilis) in this subalpine meadow. Growth form-based analyses combined with canopy height categories should be recommended to reveal general rules and mechanisms relating to grazing.

Sand couch-grass Elymus farctus (Viv.) Runemark ex Melderis subsp. boreoatlanticus (Simonet & Guin.) Melderis is a species of psammophytic perennial grass which grows on low embryo dunes, less frequently on white dunes, on a sandy substrate which is rich in chlorides, with a neutral or alkaline pH. The occurrence of E. farctus subsp. boreoatlanticus was confirmed on the Polish Baltic coast only in six stands out of 20 quoted in the 19th century and at the beginning of the 20th century, and the species is classified as critically endangered (CR). One of the largest populations of that species is situated on the Wolin Island (the Baltic Sea, west coast of Poland). The population of this species was monitored between 2015-2017 in the habitat of initial white coastal dunes (Nature 2000 site, code 2110), where the sand couch-grass is a characteristic species of Honckenyo-Agropyretum juncei R.Tx. 1955 plant association. The results of the conducted research show that the main reason for the rapid decline of the population of Elymus farctus subsp. boreoatlanticus on the western coast of Poland is recreational use of beaches, which is growing in an uncontrollable manner and puts pressure on this habitat, followed by complete destruction of psammophilous and halophilous vegetation. In addition, impact from marine abrasion inhibits the development of white coastal dunes where E. farctus subsp. boreoatlanticus occurs, and intensive aeolian sand accumulation hinder the regenerative ability of shoots and significantly limit vegetative reproduction.

Plant community assembly is determined by species turnover and intraspecific trait variations (ITV) controlled by environment changes. However, little is known about how species turnover and ITV affect the responses of plant community to habitat changes and grazing disturbance in semiarid grasslands. Here, we measured five functional plant traits in four typical grassland habitats under fencing and grazing disturbance in a semiarid grassland, Northern China, including plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC) and leaf carbon: nitrogen ratio (C:N). We also calculated the community weighted means (CWM) and non-weighted means (CM) of all traits and examined the relative roles of species turnover and ITV in affecting the responses of community traits to habitat changes and grazing disturbance. Our results showed that the CWM and CM values of five functional traits differed with grassland habitat changes. As compared to other grasslands, the Stipa steppe had the higher plant height, the sandy grassland had the higher SLA and lower LDMC, and the meadow had the lower LNC and higher C:N. Grazing decreased plant height across grassland habitats, as well as decreased SLA and increased LDMC in meadow. The responses of all community-level traits to habitat changes were driven by species turnover, while the responses of phenotypic traits (height, SLA and LDMC) to grazing were determined by both species turnover and ITV. So, we argue that ITV should be considered when understanding plant community assembly under grazing disturbance regime in semiarid grasslands.

Our aim was to determine dynamics in a population of tawny owls Strix aluco over 15-year period, in relation to year-to-year variation in environmental conditions. The research was carried out in a habitat mosaic of fields and forest in central Poland, over the 2004–2018 period. Numbers of pairs (territories) were established by the standard playback survey technique supplemented by searches for nest sites. The selected environmental factors studied in parallel were the acorn production, density changes in field and forest rodents, meteorological conditions in winter and density of martens (Martes spp.). At the start of the study period 20 nest boxes designed for tawny owls were placed out in the study area. This number was enlarged by additional 27 nest boxes placed in 2012. The number of owls in the area remained stable – in the range of 26–29 pairs, despite changes in nesting sites availability. However, moderate influence of rodent density and winter conditions on population abundance was detected. Also, peak in the rodent population coincided with greater clutch size and numbers of young owls reared. Densities of martens remained relatively stable throughout the study period, and there were no reported cases of these carnivores killing tawny owls, despite the former taking shelter in the owl-boxes.

The diversity and abundance of bumblebees (Bombus Latr.) in eight parks of Warsaw city and the impact of park size (range from 1.9 to 73 ha) as well as other selected characteristics (the percentage of the area covered by tree and the quality of park surroundings) on the bumblebee community were evaluated. In each park, bumblebees were observed along designated paths for 30 minutes. In total, 12 species of bumblebees were recorded, of which four belonged to cuckoo bumblebees (Psithyrus subgenus). We found: B. terrestris (L.), B. lapidarius, (L.), B. pascuorum (Scop.), B. hortorum (L.), B. semenoviellus (Skorikov), B. hypnorum (L.), B. ruderarius (Müller), B. pratorum (L.) and four cuckoo bumblebee species: B. (Ps.) bohemicus (Seidl.), B. (Ps.) campestris (Pz.), B. (Ps.) rupestris (F.), B. (Ps.) vestalis (Fourc.).

The size of parks, percentage of area covered by trees, and characteristics of the areas surrounding the parks were found to be not significant for the diversity and abundance of bumblebees in urban parks. However, our results indicate the importance of the semi-natural areas within the parks for the species diversity.