The small-scale variation of herb-layer community structure in a riparian mixed forest

The ground vegetation layer is the most diverse plant community in forest ecosystems. We have shown the role of spatial variables, soil properties and overstorey structure in spatial variation of the herb-layer community in a riparian mixed forest . The research was conducted in the "Dnipro-Orils’kiy" Nature Reserve (Ukraine). The research polygon was located in the forest in the floodplain of the River Protich, which is a left tributary of the River Dnipro. Plant abundance was quantified by measuring cover within an experimental polygon. The experimental polygon consisted of 7 transects, each comprising 15 test points. The distance between the rows in the site was 3 m. At the site we established a plot of 45 × 21 m, with 105 subplots of 3 × 3 m organized in a regular grid. A list of vascular plant species was composed for each 3 × 3 m subplot along with visual estimates of species cover projection. The plant community was represented by 43 species, of which 18.6% were phanerophytes, 39.5% were hemicryptophytes, 9.3% were therophytes, 7.0% were geophytes. An overall test of random labelling revealed the total nonrandom distribution of the tree stems within the site. The species-specific test of random labelling showed the nonrandom segregated distribution of Acer tataricum, Pyrus communis, Quercus robur, and Ulmus laevis. Crataegus monogyna and Euonymus europaeus were distributed randomly. The nearest neighbour of Acer tataricum was less likely to be Ulmus laevis. There was no direct spatial connection between Acer tataricum and other trees. Crataegus monogyna, Pyrus communis, Quercus robur and Euonymus europaeus were not segregated from all other species. The nearest neighbour of Ulmus laevis was less likely to be Acer tataricum. Constrained correspondence analysis (CCA) was applied as ordination approach. The forward selection procedure allowed us to select 6 soil variables which explain 28.3% of the herb-layer community variability. The list of the important soil variables includes soil mechanical impedance (at the depth 0–5, 30–35, 75–80, and 95–10 cm), soil moisture, and soil bulk density. The variation explained by pure spatial variables accounted for 11.0 %. The majority of the tree-distance structured variation in plant community composition was broad-scaled. The spatial scalograms were left-skewed asymmetric. Significant relationship was found between the pure spatial component of the community variation and a number of phytoindicator estimations, most important of which were the variability of damping and humidity. Tree stand was obseerved to be a considerable factor structuring both the herb-layer community and spatial variation of the physical properties of soil

Ecological Niche Packing and Spatial Organisation of the Urban Park Macrofauna Comminity

Abstract. The results of studying of the spatial organization of the soil macrofauna of the urbanozem of the grassland were processed by OMI- and RLQ-analysis methods. The biogeocenotical situation at the location of an experimental polygon was shown to be typical of a meadow-steppe mega-mesotrophic xeromesophic character. The data for the research was collected by means of manual sorting of the soil samples with the area of 0.25×25 cm on a regular grid (7×15 samples) with the distance between the selection points 2 m (results presented as L-table), the measurement of temperature, electrical conductivity and soil penetration resistance, the litter depth and the height of the grass (R-table). The soil macrofauna of the experimental area was represented by 27 species with a total density of 56.38 ind./м2. The ecological structure of the animal community of the soil was dominated by the pratants and silvants, mesophiles, olygotropic, endogeic topomorphs, saprophagous. Such edaphic characteristics as soil penetration resistance, electrical conductivity, litter depth, as well as height of grass, played an important role in structuring of ecological niche of macrofauna community. The first two axis of OMI analysis described 73.43% of inertia, which was sufficient for the description of the differentiation ecological niches of macrofauna on the investigated polygon to conduct in the space of the first two axes. For the average value of the marginality of the community (OMI = 2.90), the significance level was р = 0.001, which testifies to the important role of the selected environment variables for structuring of the soil macrofauna community. The four key functional groups of macrofauna were found as a result, the RLQ-analysis and the next cluster procedure and assessed the role of the edaphic factors in their spatial variation. Each of the functional groups was interpreted in terms of an ecomorphic approach

Impact of recreational transformation of soil physical properties on micromolluscs in an urban park

The paper assesses the effect of transformation of soil physical properties on the abundance of micromolluscs in the conditions of an ur-ban park. The studies were carried out in Novooleksandrivskiy Park (Melitopol, Ukraine). An experimental polygon was represented by 7 transects with 18 sampling points in each. The interval between the points in the transect, as well as the interval between transects, was 3 meters. The total area of the polygon was 1,134 m2. The tree species growing within the polygon were Quercus robur, Sophora japonica, and Acer campestre. Shrubs were represented by Ulmus laevis, Tilia cordata, Celtis occidentalis, and Morus nigra. The locations of the trees and shrubs were mapped. The crowns of tree and shrub plants formed a dense canopy and a shady light regime. The grass cover was practi-cally absent. The soil mechanical resistance, soil aggregate-size distribution, electrical conductivity of soil, soil moisture and bulk density were measured. We recorded 618 individuals of Vallonia pulchella, 120 individuals of Cochlicopa lubrica, and 58 individuals of Acanthinu-la aculeata within the surveyed polygon. We extracted three principal components, which could explain 60.9% of the variation in the feature space of the soil properties. The principal component 1 explained 42.0% of the variation of the feature space and depended on the soil pene-tration resistance throughout the whole profile, aggregate composition, density, electric conductivity and moisture content of soil. This com-ponent reflected a tendency for soil penetration resistance and soil density to increase near recreational trails. The principal component 1 was used to indicate the gradient of recreational transformation of the soil. The principal component 2 was able to explain 10.6% of the variation in the feature space. It negatively correlated with the distance from the recreational trail, soil penetration resistance at the depth of 35 cm or more, soil electrical conductivity, and the proportion of aggregates greater than 3 mm in size. This component positively correlated with soil penetration resistance at 0–5 cm depth and the proportion of aggregates less than 0.5 mm in size. This component can be interpreted as a "halo" from the recreational trail, or a gradient of indirect soil transformations adjacent to the zone of intense recreational load. The principal component 3 was able to explain 8.3% of the variation in the feature space. It positively correlated with soil penetration resistance at the depth of 20–40 cm, the proportion of 0.5–7.0 mm aggregates, and soil moisture. It negatively correlated with the proportion of aggregates larger than 7 mm and smaller than 0.25 mm. This component indicated a variation in soil properties that was induced by causes independent of recreational exposure. The extracted gradients of soil properties significantly influenced the abundance of micromollusc populations. The abundance of all species decreased after increase in recreational load. Micromollusc species responded to direct recreational exposure as plateau (C. lubrica) and asymmetric unimodal responses (V. pulchella and A. aculeata). Keywords: species response; soil properties; ecological niche; transformation; hemeroby

Impact of recreational transformation of soil physical properties on micromolluscs in an urban park

The paper assesses the effect of transformation of soil physical properties on the abundance of micromolluscs in the conditions of an ur-ban park. The studies were carried out in Novooleksandrivskiy Park (Melitopol, Ukraine). An experimental polygon was represented by 7 transects with 18 sampling points in each. The interval between the points in the transect, as well as the interval between transects, was 3 meters. The total area of the polygon was 1,134 m2. The tree species growing within the polygon were Quercus robur, Sophora japonica, and Acer campestre. Shrubs were represented by Ulmus laevis, Tilia cordata, Celtis occidentalis, and Morus nigra. The locations of the trees and shrubs were mapped. The crowns of tree and shrub plants formed a dense canopy and a shady light regime. The grass cover was practi-cally absent. The soil mechanical resistance, soil aggregate-size distribution, electrical conductivity of soil, soil moisture and bulk density were measured. We recorded 618 individuals of Vallonia pulchella, 120 individuals of Cochlicopa lubrica, and 58 individuals of Acanthinu-la aculeata within the surveyed polygon. We extracted three principal components, which could explain 60.9% of the variation in the feature space of the soil properties. The principal component 1 explained 42.0% of the variation of the feature space and depended on the soil pene-tration resistance throughout the whole profile, aggregate composition, density, electric conductivity and moisture content of soil. This com-ponent reflected a tendency for soil penetration resistance and soil density to increase near recreational trails. The principal component 1 was used to indicate the gradient of recreational transformation of the soil. The principal component 2 was able to explain 10.6% of the variation in the feature space. It negatively correlated with the distance from the recreational trail, soil penetration resistance at the depth of 35 cm or more, soil electrical conductivity, and the proportion of aggregates greater than 3 mm in size. This component positively correlated with soil penetration resistance at 0–5 cm depth and the proportion of aggregates less than 0.5 mm in size. This component can be interpreted as a "halo" from the recreational trail, or a gradient of indirect soil transformations adjacent to the zone of intense recreational load. The principal component 3 was able to explain 8.3% of the variation in the feature space. It positively correlated with soil penetration resistance at the depth of 20–40 cm, the proportion of 0.5–7.0 mm aggregates, and soil moisture. It negatively correlated with the proportion of aggregates larger than 7 mm and smaller than 0.25 mm. This component indicated a variation in soil properties that was induced by causes independent of recreational exposure. The extracted gradients of soil properties significantly influenced the abundance of micromollusc populations. The abundance of all species decreased after increase in recreational load. Micromollusc species responded to direct recreational exposure as plateau (C. lubrica) and asymmetric unimodal responses (V. pulchella and A. aculeata)

Terrain and tree stand effect on the spatial variation of the soil penetration resistance in Urban Park

The recreation loading causes soil compaction which induces negative tendencies for the urban environment. The objectives of this study were to investigate the role of relief and tree stand density in the soil penetration resistance variation within an urban park, to assess the most suitable variogram models to evaluate the autocorrelation of regression models, and to map the spatial variability of soil penetration resistance. The combination of regression and spatial models allowed the research team to evaluate the spatial variation of the soil penetration resistance on different soil layer

Assessment of the recreational transformation of the grass cover of public green spaces

The paper reveals regularities of grass projective cover variation depending on the level of recreational transformation of public green spaces, taking into account stand density and soil electrical conductivity. The hypothesis that herbaceous cover is positively influenced by moisture and trophicity of edaphotopes and the stand is an antagonist of herbaceous cover is confirmed. The nature of intra-ecosystem relationships of the park stand is influenced by the level of recreation. Assessment of the level of recreational transformation of the grass cover of green areas of public use is performed on the example of the park Novoalexandrovsky of Melitopol. Within the city park, the grass layer is influenced by natural and anthropogenic environmental factors. Based on the data on the hardness of the soil quantified the level of recreational load and set the following levels of recreational load: low level, below a moderate level, moderate level,above a moderate level and high level. Stand density is an important natural factor that affects the herb layer primarily through the regulatory function of access to sunlight. Quantitatively, trophicity and moisture can be estimated using the electrical conductivity index, which depends on both the amount of salts dissolved in the ground liquid (trophicity) and the moisture content. The obtained data show that electrical conductivity of soil within the park is on the average 0,11 ± 0,0037 dSm/m and in 95% of cases varies from 0 (electrical conductivity below the lower limit of device sensitivity) to 0,19 dSm/m. Observed electrical conductivity values are much less than critical values, so within the park, excessive salinity is not a limiting factor for herbaceous plant growth. Projective cover of the herbaceous layer is on average 2,60 ± 0,11%. In 95% of cases this indicator is in the range of 0‒10%. The level of variability of projective coverage is rather high ‒ 96,48%. Distribution asymmetry is significant and positive, indicating a significant shift in the distribution of this indicator towards small values. The kurtosis is also significant and positive, which indicates the predominance of modal values compared to the random alternative. The distribution of the projective coverage can be described as a mixture of two distributions with a normal law. The component with a lower mean of 0,76 ± 0,59% is 46,0% of the mixture, and the component with a mean of 3,63 ± 2,24% is 54,0% of the mixture. It should be noted that the Kolmogorov‒Smirnov test indicates a low level of explanatory power even for such a complex model. Therefore, it should be assumed that the variation of the projective cover of herbaceous cover is determined by a number of significant factors. According to the quantitative indicators of vegetation cover, the following levels of recreational load can be distinguished: low (combines small and less than moderate levels), medium (combines moderate and above moderate) and high(corresponds to the high level). Differences in projective cover within the smallest and below moderate level on the one hand, and medium and above moderate level on the other hand, are not statistically reliable

Persistent gender differences in spatial ability, even in STEM experts

Background: Spatial ability (SA) shows wide variability. One proposed explanation for the observed individual difference in SA is variability in interest and engagement in activities that promote spatial ability. Research also robustly shown that males on average outperform females in most aspects of SA. Previous studies have identified a number of activities that can potentially contribute to both individual and gender differences in SA, including tinkering with electronics, particular sports activities, and designing. However, the findings regarding these links are inconsistent. One way to investigate these links is to compare the groups that are intensively engaged with these activities. Aim: The present study aims to evaluate the robustness of these links by comparing SA in adolescents with expertise in STEM, arts, and sports, with their unselected peers. We also aimed to assess whether gender differences in SA are still present in expert groups. Methods: The data on ten small-scale SA tests was collected in an unselected sample of adolescents (N = 864, Mean age = 15.4, SD = 1.1); as well as in 3 samples of adolescents with expertise in STEM (N = 667, Mean age = 15, SD = 1.2); in Arts (N = 280, Mean age = 15, SD = 1.2) and in Sports (N = 444, Mean age = 14.3, SD = 0.7). Results: Out of the three expert groups, only STEM experts on average outperformed the unselected group on all SA tasks. The STEM experts also outperformed Arts and Sports experts. Gender differences persisted in all expert groups, with moderate effect sizes. Discussion: Findings support previously established links between spatial ability and STEM-related expertise. In contrast, such links were not found for expertise in arts and sports. Consistent with previous research, we found gender differences in SA for all samples, which persisted in STEM experts