In this study we evaluate how variations in taxonomic composition and physical structure of macrophyte stands affect plant-dwelling chironomid assemblages in highly variable macrophyte assemblages in two densely vegetated backwaters. By using multivariate explanatory techniques we found that similar vegetation composition did not unequivocally relate to similar chironomid assemblages, moreover the diversity of macrophyte stands did not correlate with the taxonomic diversity of chironomid assemblages in the backwaters investigated. Taxonomic composition and structural characteristics of the vegetation had little influence on the taxonomic or functional (i.e. feeding groups) composition of chironomid assemblages inhabiting them. Similarly, there are only weak relationships between the distribution of certain chironomid species or functional feeding groups and the environmental variables investigated. In general, the structure of the vegetation was more closely associated with the distribution of dominant chironomid taxa than compositional variables (i.e. density of specific macrophyte taxa). In summary, the structure of aquatic vegetation (i.e. position, size of a stand of vegetation, total plant density) and characteristics of the environment where it develops may be more important in shaping plant-dwelling chironomid assemblages than the taxonomic composition of the vegetation., Mónika Tóth ... [et al.]., and Obsahuje seznam literatury
The majority of the conservation strategies for threatened dragonflies are designed to protect only their aquatic habitats. Sympetrum depressiusculum is a species threatened not only by the destruction of its aquatic habitats but also by its association with a specific terrestrial environment. In this study, we aimed to identify the key elements of the terrestrial environment of adult S. depressiusculum. We used generalized linear mixed models to determine habitat preferences of adults and the particular features of habitat patches, such as vegetation cover, vegetation structure and the availability of potential prey. Our results indicate that S. depressiusculum adults preferred mainly riparian vegetation but beyond ponds they utilized only certain terrestrial habitats (abandoned fields, meadows, forest clearings). Adults responded positively to habitat patches with a high cover of vegetation and suitable vegetation structure. Adult abundance was affected also by the distance of patches from the natal site. In an agricultural landscape, the availability of such habitat patches may be limited and could influence the abundance and distribution of this species. We suggest that conservation efforts for this species should not only focus on the larval environment but also include suitable surrounding terrestrial habitats. Effective management around natal sites should concentrate on maintaining a heterogeneous landscape, which is extensively managed (e.g. leaving several fields fallow, maintaining managed hay meadows)., Michal Hykel, Filip Harabiš, Aleš Dolný., and Obsahuje bibliografii
Cephalozia macrostachya Kaal. has been recently found in the ‘Swamp’ mire near Doksy (Northern Bohemia). The following revision of herbarium specimens of Cephalozia loitlesbergeri Schiffn. revealed one more specimen of C. macrostachya, collected already in 1965 in the Krušné hory Mts. The habitat preferences for both species in Central Europe are discussed and it is assumed that while C. loitlesbergeri is a clearly upland species of open, acidic raised bogs, C. macrostachya seems to prefer lowland poor fens or lagg parts of bogs in middle altitudes.
The habitat selection of European beaver (Castor fiber) was studied in Central Moravia (the Czech Republic). The Global Positioning System and Geographic Information System were used for mapping the habitat types and marks of beaver activity. Used and available habitats were compared by compositional analyses in two levels. Comparison of habitat use from home range compared to habitat availability in the study area gave Λ = 0.335 (P = 0.001), a simplified matrix ranked beaver habitat in the order: riverine willow scrub > willow- poplar forests of lowland rivers > hardwood forests > spruce plantations > meadows > reed and tall sedge beds > fields > river gravel banks > ruderal vegetation > oak-hornbeam forests > urbanized areas > ash-alder alluvial forests. Use of the habitat types based on the distribution of cut trees differed significantly from the habitat distribution within the home ranges (for habitat use quantified by number of cut trees Λ = 0.168, P = 0.001; for habitat use quantified by the time a beaver needs to cut trees Λ = 0.251, P = 0.003), the ranking matrix was: riverine willow scrub > willow-poplar forests of lowland rivers > ash-alder alluvial forests > hardwood forests of lowland rivers.
Food habits of blue sheep, Pseudois nayaur in the Helan Mountains of China were studied from November 2003 to October 2004 to better understand diet composition, seasonal variation, and feeding habitat preference. Blue sheep consumed 41 plant species that contributed >0.01% to the diets. During autumn, winter, and spring, primary species consumed were Stipa spp., Ulmus pumila, and Poa spp. Blue sheep also showed the different preference for these plant species. Graminoids were the largest proportion of the diet (36.7–58.8%) throughout the year, followed by the tree and shrub categories. Sedges were the smallest proportion of the diet (0.7–7.1%). Among the four habitat types, blue sheep showed pronounced preference for montane woodland steppe. Differences in the diets of Helan Mountains blue sheep from those of blue sheep elsewhere may reflect adaptations for geographical range, vegetation, and other factors.
The invasion of Paulownia tomentosa (Paulowniaceae), a new alien tree species in Central Europe, native to China, is analysed. By using its distribution in Austria, the invasion of this country is analysed in detail. The first reports of P. tomentosa in Austria were in the 1960s in Vienna. Since then, the number of sites has increased exponentially, with a total of 151 sites in 27 grid cells of the Floristic Mapping project of Austria. The number of sites per grid cell is strongly positively correlated with the minimum residence time in grid cell, which explains 86% of the deviance in the general linear model (GLM). The localities are confined to warm lowland areas (below 450 m altitude) and are concentrated in cities, with 90% of all localities recorded in cities with > 100,000 inhabitants. Paulownia tomentosa typically occurs in small populations of less then 10 individuals (83% of all records) and behaves as a pioneer species colonizing mainly disturbed urban habitats. Near-natural habitats, e.g. forest clearings and riparian shrubberies are rarely colonized. In extremely disturbed areas, the average number of vascular plant species is low (8.9 species), as is total plant cover (17%). As P. tomentosa is currently mostly confined to synanthropic habitats in urban areas, the invasion is not yet a nature conservation issue. In the future, predicted climate change might allow P. tomentosa to spread beyond its current distribution. The habitat preference in the eastern USA indicates that further spread of P. tomentosa in Central Europe might be accompanied by a switch to more natural habitats, e.g. forest clearings and forest margins. Thus, the future spread of this species should be closely monitored.
Variation in genome size in a particular taxonomic group can reflect different evolutionary processes including polyploidy, hybridization and natural selection but also neutral evolution. Using flow cytometry, karyology, ITS sequencing and field surveys, the causes of variation in genome size in the ecologically and morphologically diverse high-Andean genus Lasiocephalus (Asteraceae, Senecioneae) were examined. There was a 1.64-fold variation in holoploid genome size (C-values) among 189 samples belonging to 20 taxa. The most distinct was a group of plants with large genomes corresponding to DNA triploids. Disregarding the DNA triploids, the remaining samples exhibited a pronounced (up to 1.32-fold) and rather continuous variation. Plants with the smallest genomes most likely represent intergeneric hybrids with the closely related and sympatric Culcitium nivale, which has a smaller genome than Lasiocephalus. The variation in genome size in samples of diploid Lasiocephalus was strongly correlated with several environmental and life history traits (altitude, habitat and growth form). However, all these factors, as well as genome size itself, were correlated with phylogeny (main split into the so-called ‘forest’ and ‘páramo’ clades), which most probably represents the true cause of the differentiation in intrageneric genome size. In contrast, relationships between genome size and phylogeny were not apparent at lower divergence levels. Instead, here we suggest that ecological conditions have played a role in driving shifts in genome size between closely related species inhabiting different environments. Collectively, this study demonstrates that various evolutionary forces and processes have shaped the variation in genome size and indicates that there is a need for multi-approach analyses when searching for the causes and consequences of changes in genome size.
1. In Great Britain the distribution of the riverine damselfly Calopteryx splendens is predominantly southern. However, the last decade has seen records of the species in previously unoccupied areas in the northeast of England, prompting speculation regarding northward range expansion. The current study is the first to quantify the physical features of the habitat that influence the presence of C. splendens.
2. A field survey was carried out on the physical characteristics of habitat supporting C. splendens along a section of the River Wharfe, West Yorkshire, U.K. Adult C. splendens were marked uniquely for individual identification in order to assess the occurrence of the species within different habitat patches of the study area.
3. A multiple logistic regression was used to identify the significant habitat variables in explaining the occurrence of adult C. splendens.
4. The most important habitat factor in determining the presence of C. splendens was the height of the vegetation at the edge of the river. Significant negative relationships were found between the presence of C. splendens and tree coverage along the bank, and between its presence and increased bank height.
5. The distribution of C. splendens is affected by the natural physical features of the habitat, anthropogenic disturbance and the behaviour of the species itself.
6. The importance of quantitative habitat data in species conservation, particularly with regard to range expansion, is discussed.
The number of colonies of red wood ants (Formica rufa group) in the north western part of Belgium has declined by more than half over the past 20 years. In the study area of 20 × 50 km there are currently only 36 colonies of two species of red wood ants (Formica rufa and F. polyctena). Both species form both monodomous and polydomous colonies. Monodomous F. rufa colonies occur in large areas of open woodland dominated by Pinus sylvestris. The other three types of red wood ant (F. rufa polydomous, F. polyctena mono- and polydomous) occur in clearings or along the margins of small areas of deciduous or mixed woodland. The extinction of red wood ants cannot be attributed to a loss of their main habitat. Their decline in abundance, however, appears to be due to the deterioration in their habitat caused by several factors. Shading by overgrowing shrubs and the closure of the tree canopy, nearby intensive agriculture, urbanisation and use of the forest for recreation are the more important factors threatening and ultimately leading to the extinction of colonies. At poor quality sites there are no or very few nests of Serviformica ants, which initially serve as host ants and are necessary for recolonization by red wood ants. Thus, it is unlikely that these sites will be recolonized. To conserve red wood ants and maintain populations there is an urgent need to undertake certain measures, especially in areas outside nature reserves. For this there is a need to create clearings in the woodland, reduce shading due to overgrowing shrubs and closure of the tree canopy, and mitigate the effects of intensive agriculture, urbanisation and recreation. It is important that the effects of these measures should be monitored.
A study of home range and habitat use was carried out on grey partridge (Perdix perdix) in a high density population (24–33 pairs /km2) in the south-west part of Praha, Czech Republic from 1997 to 1999. Radiotracking of individual partridge was used in the study (n = 11). Breeding period (March – June 15) and post-breeding period (June 16 – October) were analysed separately. Home range size (minimum convex polygon 95%) in the breeding period averaged 3.7 ha with a significant increase up to 8.7 ha in the post-breeding period. The majority of partridge ranges were located within dominant crop fields and idle habitats (unmanaged early stages of plant succession) referred to as weeds. Both high population density and small individual home ranges may result from the wide availability of weeds, whose attractiveness was probably due to availability of nesting sites, sufficient food supply for both partridge chicks and adults and adequate escape cover. Despite a high population density, there is an indication of little home range overlaps between pairs during the breeding period.