Zdeňka Lososová

Weed vegetation of arable land in Central Europe: Gradients of diversity and species composition

Abstract Question: What are the main broad-scale spatial and temporal gradients in species composition of arable weed communities and what are their underlying environmental variables? Location: Czech Republic and Slovakia. Methods: A selection of 2653 geographically stratified relevés sampled between 1954–2003 was analysed with direct and indirect ordination, regression analysis and analysis of beta diversity. Results: Major changes in weed species composition were associated with a complex gradient of increasing altitude and precipitation and decreasing temperature and base status of the soils. The proportion of hemicryptophytes increased, therophytes and alien species decreased, species richness increased and beta diversity decreased with increasing altitude. The second most important gradient of weed species composition was associated with seasonal changes, resulting in striking differences between weed communities developed in spring and summer. In summer, weed communities tended to have more neophytes, higher species richness and higher beta diversity. The third gradient reflected long-term changes in weed vegetation over past decades. The proportion of hemicryptophytes and neophytes increased, while therophytes and archaeophytes decreased, as did species richness over time. The fourth gradient was due to crop plants. Cultures whose management involves less disturbances, such as cereals, harboured less geophytes and neophytes, and had higher species richness but lower beta diversity than frequently disturbed cultures, such as root crops. Conclusions: Species composition of Central European weed vegetation is mainly influenced by broad-scale climatic and edaphic factors, but its variations due to seasonal dynamics and long-term changes in agricultural management are also striking. Crop plants and crop-specific management affect it to a lesser, but still significant extent. Nomenclature: Kubát et al. (2002).

Classification of Weed Vegetation of Arable Land in the Czech Republic and Slovakia

Numerical classification of 2653 geographically stratified relevés of weed vegetation from the Czech and Slovak Republics was performed with cluster analysis. Diagnostic species were determined for each of the seven main clusters using statistical measures of fidelity. The classification reflected clear distinctions between lowland (mostly calcicole) and highland (mostly calcifuge) sites, spring and summer phenological stages, and cereals and root crops. The results of the cluster analysis were compared with traditional phytosociological units. Two clusters corresponded to calcifuge weed vegetation of theScleranthion annui alliance; one cluster represented the vegetation of root crops on moist soils of theOxalidion europaeae alliance; one cluster contained thermophilous weed vegetation of theCaucalidion lappulae alliance; two clusters included weed vegetation of root crops and of stubble fields, which can be assigned to theCaucalidion, Panico-Setarion,Veronico-Euphorbion andEragrostion alliances; one cluster included vernal weed vegetation in little disturbed habitats of theCaucalidion lappulae andScleranthion annui alliances. Our analysis did not support the concept of theSherardion andVeronico-Taraxacion alliances, which were included in earlier overviews of the vegetation units of the Czech Republic and Slovakia.

Rocks and Walls: Natural Versus Secondary Habitats

Walls are often considered secondary habitats for vegetation of natural rock surfaces. Compared with rocks, walls differ in many features, for example the presence of a binding material (mainly calcareous mortar), location in settlements and exposure to human impact. A data set of 1,205 phytosociological relevés recorded on horizontal wall tops, wall verticals and rock verticals in the Czech Republic was used to compare their vegetation with regard to i) species composition (frequent species, species diversity, endangered and alien species) and ii) the ecological requirements of the respective species. Gamma diversity of vascular plant species was comparable in all habitat types (242 species on wall tops, 212 species on wall verticals and 197 species on rock verticals). Wall verticals had higher beta diversity, but lower alpha diversity than rocks. Remarkable differences were found comparing the diversity of alien species. Whereas alpha and gamma diversities of aliens were higher on both wall habitats, beta diversity of aliens was the highest on rocks. The high floristic heterogeneity of walls is mainly attributable to the large pool of species from the surrounding urbanized landscape (e.g., cultivated ornamental species and synanthropic weeds) that are favoured by high nutrient inputs. In contrast, species characteristic of rocks are mainly substrate specialists. Walls and rocks share the frequent occurrence of ferns, grasses and herbs typical of forest understorey and clearings. Compared with rocks, walls are generally colonized by species requiring higher nutrient content, soil reaction, temperature and moisture. Secondary wall habitats might be suitable for some rare and endangered species, but contrary to rocks their occurrences are only accidental and temporary. The representation of aliens was considerably higher on walls (approximately 35%) than on rocks (9%).

Diversity and Biotic Homogenization of Urban Land-Snail Faunas in Relation to Habitat Types and Macroclimate in 32 Central European Cities

The effects of non-native species invasions on community diversity and biotic homogenization have been described for various taxa in urban environments, but not for land snails. Here we relate the diversity of native and non-native land-snail urban faunas to urban habitat types and macroclimate, and analyse homogenization effects of non-native species across cities and within the main urban habitat types. Land-snail species were recorded in seven 1-ha plots in 32 cities of ten countries of Central Europe and Benelux (224 plots in total). Each plot represented one urban habitat type characterized by different management and a specific disturbance regime. For each plot, we obtained January, July and mean annual temperature and annual precipitation. Snail species were classified into either native or non-native. The effects of habitat type and macroclimate on the number of native and non-native species were analysed using generalized estimating equations; the homogenization effect of non-native species based on the Jaccard similarity index and homogenization index. We recorded 67 native and 20 non-native species. Besides being more numerous, native species also had much higher beta diversity than non-natives. There were significant differences between the studied habitat types in the numbers of native and non-native species, both of which decreased from less to heavily urbanized habitats. Macroclimate was more important for the number of non-native than native species; however in both cases the effect of climate on diversity was overridden by the effect of urban habitat type. This is the first study on urban land snails documenting that non-native land-snail species significantly contribute to homogenization among whole cities, but both the homogenization and diversification effects occur when individual habitat types are compared among cities. This indicates that the spread of non-native snail species may cause biotic homogenization, but it depends on scale and habitat type.

Chorological spectra of arable weed vegetation types in the Czech Republic.

A data set of 2,743 phytosociological releves was used for a comparison of the basic chorological characteristics of the main vegetation types of weed vegetation in the Czech Republic. All releves were classified by the cocktail method into the alliances: Caucalidion, Scleranthion annui, Veronico-Euphorbion, Oxalidion fontanae, Spergulo-Erodion and Arnoseridion minimae. The proportions of native species, archaeophytes and neophytes, as well as the proportion of species with particular distribution range types were calculated for each releve. The weed vegetation in the data set contained 560 species: 38.3 % of them were native, 56.2 % were archaeophytes and 5.5 % were neophytes. The highest proportion of natives was found for the weed vegetation of poor sandy soils (alliance Arnoseridion minimae) and of humid areas (alliance Oxalidion fontanae). The highest proportion of archaeophytes was found in the thermophilous weed vegetation of Caucalidion and Spergulo-Erodion alliances, and the highest proportion of neophytes in Spergulo-Erodion alliance. Czech weed vegetation is predominantly composed of species of Euroasian temperate range type. These species prevail in weed vegetation of alliances Scleranthion annui and Oxalidion fontanae. Macaronesian-Mediterranean range types and Oriental-Turcestani-Mediterranean range types make up 25-38 % of all weed species growing in the Czech Republic. These Mediterranean species dominate in the weed vegetation of alliances Caucalidion and Arnoseridion minimae, followed by alliances Veronico-Euphorbion and Spergulo-Erodion. The proportion of central European species is similar (about 10 % of species) in all the compared vegetation types except Spergulo-Erodion, where these species are rarer (only 5 %). Other chorological types are scarcely present in the weed vegetation of the Czech Republic.

Life-history traits controlling the survival of Tillaea aquatica: a threatened wetland plant species in intensively managed fishpond landscapes of the Czech Republic

Tillaea aquatica (Crassulaceae) is considered as annual wetland species threatened by changes in land use and progressing eutrophication in large part of its European distribution range. We summarised the historical and recent data on this species, and analysed its distribution and associated habitat changes in the Czech Republic. We used permanent plots as well as seed bank and seed dispersal studies to obtain better insight into the plant’s survival strategy. During the second half of the twentieth century T. aquatica disappeared from most historical localities situated mainly in large fishponds. After 1999, altogether 18 new populations were found in small fry ponds and other fish-farming ponds. The largest populations of Tillaea were found in ponds with long-term bottom exposure where the vegetation of perennial herbs was eliminated by herbicides or grazing. Propagules easily dispersible by water, on gumboots or tyres of vehicles, and long-term soil seed bank also might contribute to persistence of the species in the habitats, diminishing the chance of extinction. As the fishpond management has changed, and so have done the original habitats of Tillaea, the species could survive in habitats different from those in the past. In this article, we suggest management measures aimed at promoting survival of Tillaea under new circumstances.

Decoupling phylogenetic and functional diversity to reveal hidden signals in community assembly

Summary Functional traits and phylogeny offer different, and often complementary, information about ecological differences between species, an essential step to uncover biodiversity assembly mechanisms and their feedbacks to ecosystem functions. However, traits and phylogeny are often related due to underlying trait evolution. Consequently, when combined, their shared information can be overemphasized, hindering their complementarity. It is therefore desirable to decouple their unique and overlapping contributions. We propose a conceptual and mathematical framework that produces a set of meaningful measures of ecological differences between species. We test the properties of these measures and the validity of the approach with extensive simulated data to show (i) the information provided by decoupling traits from phylogeny and vice versa, and (ii) that decoupling trait and phylogenetic information can uncover otherwise hidden signals underlying species coexistence and turnover. The application of the approach is further illustrated using a large dataset of Central European meadows as a case study. Decoupling traits and phylogeny particularly reveals the importance of differentiation between phylogenetically related species, which can be essential to understand species replacements along environmental gradients and the combined action of environmental filtering and limiting similarity within communities. Decoupling traits and phylogeny provides an avenue for connecting macro-evolutionary and local factors affecting coexistence and for understanding how complex species differences affect multiple ecosystem functions. We present an R function called ‘decouple’, which allows a simple and wide application of the framework.

Organic, integrated and conventional management in apple orchards: effect on plant species composition, richness and diversity

The study was conducted to assess the eff ect of conventional, integrated and organic management on diff erences in plant species composition, richness and diversity. The plants were studied in triads of orchards situated in three regions of the Czech Republic. Data about species occurrences were collected on 15 permanent plots in the tree rows and 15 plots between tree rows in each of the apple orchards during 2009. A total of 201 vascular plant species (127 native species, 65 archaeophytes, and 9 neophytes) were found. Management type and also diff erent regional conditions had a signifi cant eff ect on plant species composition and on diversity parameters of orchard spontaneous vegetation. Species richness and species pool was signifi cantly higher in the organic orchards than in the diff erently managed orchards. Management type had signifi cant eff ect on proportions of archaeophytes, and also neophytes in apple orchards.

Which traits influence the frequency of plant species occurrence in urban habitat types

Plants in cities must cope with various anthropogenic environments that differ from surrounding landscapes. Moreover, the differences in biotic and abiotic conditions among these habitats filter species with suitable traits and niche requirements. Here we aim to identify those attributes that promote species occurrence across and within urban habitat types of large cities. Species composition of spontaneously occurring vascular plant species was recorded in 1-ha plots in seven different urban habitat types in each of 32 European cities. Each species was characterized in terms of dispersal type, growth form, height, seed bank longevity, seed mass, selected leaf traits and ecological indicators including Ellenberg indicator values, Grime’s life strategies, and immigration pathways using information from available species-trait databases. For each species, total frequency of occurrence across all plots and habitat frequency of occurrence across plots of given habitat types were calculated and regression trees were used to relate them to traits and ecological indicators. The most frequently occurring species in the cities tended to be human-dispersed, nutrient-demanding plants that prefer drier to mesic soil conditions. These species do not possess the S-strategy and usually produce seeds of low mass forming short-term persistent seed banks. Habitat-specific responses were also revealed, indicating the effects of between- and within-habitat heterogeneity on trends in species performance in cities. Such patterns can be overlooked when differences in species occurrences in particular urban habitat types are not considered; thus, habitat-specific responses can resolve inconsistencies found when whole urban floras are analysed as a whole.

Urban ornamental trees: a source of current invaders; a case study from a European City

Human made habitats are considered to be important hotspots of biodiversity of native as well as alien plant species. Due to high propagule pressure caused by human activities they serve as a source of introduction of alien plant species. We used the database of planted ornamental trees and shrubs for Brno, Czech Republic, to determine the significance of introduction effort given by intensity of planting as a factor in woody plant naturalization. Of all planted woody taxa, 15% were recognized as spontaneously growing in the urban area and there was a significant relationship between the number of planted individuals and the ability of a species to spontaneously occur in the urban area. The most often spontaneously escaping species originated in Europe (55%), followed by neophytes from North America (21%) and Central and Eastern Asia (14%). Although only a minor portion of planted woody species is able to escape from cultivation, this still could represent a potential risk for the native vegetation.