Zdeněk Janovský

Competition among native and invasive Impatiens species: the roles of environmental factors, population density, and life stage

We examined competition effects in an experiment with three Impatiens species (Balsaminaceae) sharing similar life-history characteristics and habitats: the native I. noli-tangere, and two invasive species, I. parviflora and I. glandulifera. The results suggest that the effect of competition on the performance of invasive Impatiens species exceeds that of environmental factors, i.e. light and soil moisture. Competitive interactions with co-occurring congeners may thus be a more important predictor of the invasion success of an invasive species and its population dynamics than its response to abiotic factors, and should be taken into account when evaluating their invasion potential.

Conspecific and Heterospecific Plant Densities at Small-Scale Can Drive Plant-Pollinator Interactions

Generalist pollinators are important in many habitats, but little research has been done on small-scale spatial variation in interactions between them and the plants that they visit. Here, using a spatially explicit approach, we examined whether multiple species of flowering plants occurring within a single meadow showed spatial structure in their generalist pollinator assemblages. We report the results for eight plant species for which at least 200 individual visits were recorded. We found that for all of these species, the proportions of their general pollinator assemblages accounted for by particular functional groups showed spatial heterogeneity at the scale of tens of metres. This heterogeneity was connected either with no or only subtle changes of vegetation and flowering species composition. In five of these species, differences in conspecific plant density influenced the pollinator communities (with greater dominance of main pollinators at low-conspecific plant densities). The density of heterospecific plant individuals influenced the pollinator spectrum in one case. Our results indicate that the picture of plant-pollinator interactions provided by averaging data within large plots may be misleading and that within-site spatial heterogeneity should be accounted for in terms of sampling effort allocation and analysis. Moreover, spatially structured plant-pollinator interactions may have important ecological and evolutionary consequences, especially for plant population biology.

Shell decomposition rates in relation to shell size and habitat conditions in contrasting types of Central European forests

Empty mollusc shells provide evidence of the species’ presence over various temporal and spatial scales. However, the persistence of the shell can differ depending on the levels of soil pH and soil humidity. Although this is generally known, there are virtually no experimental data on shell decomposition rate and its relation to shell size and site conditions. Here we study disappearance and degradation rates of shells of nine common species covering the variation in shell size and ecological requirements of temperate European land snails. These shells were exposed to decomposition during a 3-year field experiment in six forest types, representing a gradient of soil pH and humidity. Rates of disappearance and (in larger species) of degradation were estimated by removing the exposed shells and measuring their condition after 6, 12, 24 and 36 months. The disappearance rate was modelled by generalized linear models in relation to species and forest type. The data showed an increase in shell disappearance rate from dry alkaline through to wet acidic forests, but the effect of species size outweighed that of habitat. While shells of large species only started to disappear after 3 years in wet acidic sites, most shells of small species had already disappeared by that time. In contrast, in dry habitats the loss of small shells only started after 3 years. The results clearly support the benefits of using empty shells in mollusc research, especially less damaged shells, which represent the individuals that were alive less than 2 years ago, regardless of shell size and habitat type. However, the marked differences in decomposition rate related to shell size and habitat also highlight the need to take these into account if a studied parameter is confounded with variation in shell size and/or site alkalinity or humidity.

Exposure to airborne fungi during sorting of recyclable plastics in waste treatment facilities

BACKGROUND In working environment of waste treatment facilities, employees are exposed to high concentrations of airborne microorganisms. Fungi constitute an essential part of them. This study aims at evaluating the diurnal variation in concentrations and species composition of the fungal contamination in 2 plastic waste sorting facilities in different seasons. MATERIAL AND METHODS Air samples from the 2 sorting facilities were collected through the membrane filters method on 4 different types of cultivation media. Isolated fungi were classified to genera or species by using a light microscopy. RESULTS Overall, the highest concentrations of airborne fungi were recorded in summer (9.1×103-9.0×105 colony-forming units (CFU)/m3), while the lowest ones in winter (2.7×103-2.9×105 CFU/m3). The concentration increased from the beginning of the work shift and reached a plateau after 6-7 h of the sorting. The most frequently isolated airborne fungi were those of the genera Penicillium and Aspergillus. The turnover of fungal species between seasons was relatively high as well as changes in the number of detected species, but potentially toxigenic and allergenic fungi were detected in both facilities during all seasons. CONCLUSIONS Generally, high concentrations of airborne fungi were detected in the working environment of plastic waste sorting facilities, which raises the question of health risk taken by the employees. Based on our results, the use of protective equipment by employees is recommended and preventive measures should be introduced into the working environment of waste sorting facilities to reduce health risk for employees. Med Pr 2017;68(1):1-9.

Accounting for clonality in comparative plant demography – growth or reproduction?

Clonal growth occurs in a high proportion of herbaceous plant species, but it is difficult to deal with in demographic transition matrix models. It is primarily a growth process, but in many cases gives rise to new individuals from the viewpoint of plant demography. In the present contribution, we review how clonality is treated in existing demographic studies of clonal species from the Central European flora. We based our analyses on publicly accessible data in the COMPADRE and CLO-PLA databases and compiling from these information on plant matrix population models (hereafter MPMs) and clonal traits. Out of the 55 species × study combinations of species with known clonality, ca 30% neglect clonality. Another 30% treat clonal growth as growth of mother ramet and only the remaining 40% address clonality as a separate reproductive pathway. However, but only about half of these studies (12; 22% of total) reported a separable submatrix of clonal transitions necessary for comparative analyses. Here we show that failure to report clonal transitions separately leads to a serious bias in estimation of many demographic characteristics derived from MPMs, such as generation time. Shoot ontogeny (namely shoot lifespan and its branching architecture) largely determined whether clonality was neglected, treated as growth or treated as reproduction. Additionally, species with long runners were under-represented in demographic studies relative to their proportion in the Central European clonal flora. To conclude, we discuss how to construct MPMs for species with varying degree of ramet integration. We recommend that demographic analyses should focus on ramets – the smallest unit capable of living through all life-cycle stages of the species – as a sampling and study unit of plant populations.

Methods of sampling airborne fungi in working environments of waste treatment facilities.

OBJECTIVES The objective of the present study was to evaluate and compare the efficiency of a filter based sampling method and a high volume sampling method for sampling airborne culturable fungi present in waste sorting facilities. MATERIAL AND METHODS Membrane filters method was compared with surface air system method. The selected sampling methods were modified and tested in 2 plastic waste sorting facilities. RESULTS The total number of colony-forming units (CFU)/m3 of airborne fungi was dependent on the type of sampling device, on the time of sampling, which was carried out every hour from the beginning of the work shift, and on the type of cultivation medium (p < 0.001). Detected concentrations of airborne fungi ranged 2×102-1.7×106 CFU/m3 when using the membrane filters (MF) method, and 3×102-6.4×104 CFU/m3 when using the surface air system (SAS) method. CONCLUSIONS Both methods showed comparable sensitivity to the fluctuations of the concentrations of airborne fungi during the work shifts. The SAS method is adequate for a fast indicative determination of concentration of airborne fungi. The MF method is suitable for thorough assessment of working environment contamination by airborne fungi. Therefore we recommend the MF method for the implementation of a uniform standard methodology of airborne fungi sampling in working environments of waste treatment facilities.