Based on a combination of data from the Czech National Phytosociological Database and expert knowledge, a database of vascular plant species pools for 88 habitats, representative of the diversity of Czech vegetation, was compiled. This database contains 1820 native species, 249 archaeophytes and 278 neophytes, each assigned to one or more habitats. Besides the data on species occurrence in different habitats, the database contains information on a species’ ecological optimum in the habitat or its dominance. The largest pools of native species were found in rather rare habitats of dry and warm herbaceous or woody habitats at low altitudes, some of which contain > 530 species (maximum of 695 species for thermophilous forest fringes). These were followed by common habitats on mesic soils. The smallest pools of native species were in saline, aquatic and bog habitats ( 350 native species always contained > 5 archaeophytes and > 5 neophytes, and often many more. Two hundred and thirty two native species, 18 archaeophytes and 30 neophytes were identified as potential dominants in at least one habitat. However, potentially dominant species made up less than 3% of the species pool for 78 out of 88 habitats. Larger percentages (up to 14.6%) of potential dominants were included in habitats with small species pools and species-poor stands (e.g., aquatic, saline and mire habitats). The number of habitats in which a species occurred was used as a measure of its ecological range. Most ecological generalists were found among the native species, less among the archaeophytes and least among the neophytes. Out of the 36 species that occur as dominants in three or more habitats, 34 were native (many are grasses), onewas an archaeophyte (Cirsium arvense) and one was a neophyte (Impatiens parviflora).
Vegetation succession was studied for 12 years on an abandoned nutrient-poor small field surrounded by a strip of natural grassland. No fertilizers or herbicides were applied. Few weeds or annuals were present during this period. Only two plants, i.e. Agrostis capillaris and Festuca rubra, dominated during the 12 years. At two spatial scales (0.04 and 0.4 m2 ) a dramatic increase in species richness was recorded during the first two years. However, no further trend in species richness occurred after the sixth year of succession. Successional changes were directed and continuous. The rate of succession depended on the distance from the neighbouring meadow. Vegetation at the margins of the transect developed more slowly and diverged from the middle during the succession.
I analyzed data from 1870 vascular floras from regions within North America to assess whether the determinants of native and alien diversity vary as a function of spatial grain. Moving window multiple regression revealed that richness of both native and alien species exhibit the expected species-area relationship, latitudinal gradient, elevation gradient, and year of publication effect. However, the strength of these factors varied between native and alien species, and as a function of scale. Alien diversity was more predictable than native diversity, and is more strongly related to elevation and latitude. For both groups, the latitudinal gradient is most pronounced at broad grains, and the elevational gradient is most pronounced at fine grains.
1. A study was made by knockdown sampling and branch clipping of the arthropod fauna of two native oaks (Quercus petraea and Q. robur) and of two introduced species (Q. cerris and Q. ilex) in woods near Oxford, U.K., and of two native species (Q. ilex and Q. pubescens) in southern France. Sampling was undertaken for five years in England and four years in France. All the phytophagous species except Acarina and Cecidomyidae from the Oxford samples were identified to species.
2. In England a marked seasonal pattern was observed in all years: chewing insects peaked in May, followed sequentially by sucking species, leaf miners and gall formers. The May peak on the native trees is much larger in terms of individuals, and especially in biomass, than on the introduced species. This peak is well known to provide an important food source for several species of woodland bird.
3. Most phytophages were much less abundant on the introduced oaks than on the native species. This is probably due more to the features of the leaves, than to the introduced status per se.
4. The species richness of the fauna was estimated by three methods on the basis of the total projected number of species (Smax), and its specificity to oak by reference to the known host range as recorded in the standard reference works.
5. The species richness of Heteroptera and Coleoptera on the deciduous oaks in their natural habitats (Q. petraea and Q. robur in England, Q. pubescens in France) are similar.
6. The fauna of the evergreen Q. ilex has a similar species richness both in France, where it is native, and in England, where it is introduced and where its phytophage guild is smaller than that of the deciduous species. In England the extent of oak specificity on Q. ilex is less than that of the deciduous species.
7. In England the phytophage fauna of the deciduous and introduced Q. cerris has a species richness considerably greater than that found on Q. ilex, but somewhat less than that of the deciduous and native oaks. However, the specificity of this fauna to oaks was not significantly different to that of the fauna on the native oaks.
We assessed vegetation changes on acidic sandy soils in permanent plots to follow secondary succession after cessation of intensive goose breeding in E Hungary. We also aimed to estimate the time required for vegetation regeneration and indicate differences in secondary succession patterns at different altitudes in sand dunes. Two sites in the low and two in the high parts of the dunes were chosen and sampled for twelve years. The initial stages are characterized by ruderal communities dominated by nitrophilous annual weeds. Ruderal vegetation was soon replaced by nutrient-poor communities dominated by short-lived pioneer dicotyledonous plants and grasses. In the last few years of the study, coinciding with a rainy period, the low sites were dominated by the perennial grasses, Poa angustifolia, P. pratensis and Cynodon dactylon. In contrast, in the high sites a less dense cover of perennials developed. The influence of initial composition on vegetation development decreased with time and the influence of altitude increased during succession. The altitude of the site had a significant effect on regeneration. Species richness and Shannon diversity of the high sites increased during vegetation development and that of the lowsites decreased. Most annuals persisted in the high sites but became extinct in the low sites. The mean species turnover rate, irrespective of altitude, decreased during the study.
In 1966, the Černíkovice experiment, Czech Republic, was started when an alluvial meadow dominated by Alopecurus pratensis was subjected to the following fertilizer treatments: non-fertilized control, PK, N50PK, N100PK, N150PK, and N200PK. The experimental plots were cut three times per year in the initial phase of the experiment and twice per year since the late 1980s. In mid May 2005, plant cover was visually estimated, biomass yield and sward height measured in order to detect changes in the grassland ecosystem caused by this long-term fertilizer treatment. After 40 years treatment was a significant predictor of sward structure, explaining 32% of the variability in plant cover data in RDA. Legumes were not detected in the N200PK treatment and achieved the highest cover in the control and PK treatment. Grasses had the lowest cover in the PK treatment and control, which significantly differed from all treatments with N. Alopecurus pratensis prevailed in all NxPK treatments. Herbs had the highest cover in the control followed by the PK treatment and both treatments significantly differed from the NxPK treatments. Achillea millefolium was recorded in all treatments, but the highest cover was recorded in the control treatment. Species richness of vascular plants ranged from 8 per m2 in the N200PK treatment to 24 in the control. A significant decrease in species richness with increase in sward height was detected. The cover of mosses ranged from 1 to 6% like sward height gradually increased with fertilizer application. Aboveground biomass yield was significantly lower in the control than all other treatments. Based on the results of the Černíkovice experiment and a comparison with other long-term fertilizer experiments it is concluded that naturally highly productive grasslands are much less threatened by the inappropriate application of fertilizers than low productive grasslands with a specific plant species composition.
The intermediate disturbance hypothesis predicts that species diversity in biotic communities should peak at intermediate levels of disturbance. The vegetation of eight calcareous screes in the Northern Calcareous Alps, Austria was studied to test this hypothesis. Data on total vegetation cover and on cover of individual species were obtained from 0.25 m2 , 0.5 m2 , and 1.0 m2 plots. An index [100 – vegetation cover (%)] was used as a surrogate for direct quantification of disturbance (movement of stones and destruction of biomass). Its suitability was substantiated by the observation of position changes of marked stones after two years. In agreement with the intermediate disturbance hypothesis, significant unimodal responses of both species richness and species diversity to disturbance were found using plots of all three sizes. However, the maxima of species richness- and species diversity-disturbance curves were shifted towards higher vegetation cover (= lower disturbance) with increasing mean diameters of the scree-building stones. This shift can be interpreted either as a synergistic effect of disturbance frequency combined with disturbance intensity/extent, or as a result of an increase in spatial heterogeneity promoting species coexistence in successionally more advanced patches of vegetation.
1. A study was made by knockdown sampling and branch clipping of the arthropod fauna of the canopy of two native oak species (Quercus robur and Q. petraea) and of two introduced species (Q. cerris and Q. ilex ) in woods near Oxford, UK, and of two native species (Q. pubescens and Q. ilex) in southern France. Sampling was undertaken for five years in the UK and for four years in France. All the specimens from the UK, except Acarina, Collembola and Nematocera were identified to species or, occasionally, to morphotype.
2. In terms of overall numbers, species richness and biomass, the results for Q. robur and Q. petraea in the UK were very similar. Their samples contained over three times the biomass and nearly double the number of species compared with those from the introduced oak species (Q. cerris and Q. ilex).
3. The ordinal composition was very similar on Q. robur and Q. petraea, and that on Q. cerris showed closer concordance to the composition of these trees than to that of Q. ilex in the UK. The ordinal composition of the faunas of the two native oak species in France showed closer concordance to each other than to any of the oak species in the UK. The proportion of Psocoptera was much higher in the UK, and that of Thysanoptera was higher in France.
4. The guild composition in terms of numbers, species richness and biomass were closely correlated on Q. robur and Q. petraea, and on Q. robur in two different woods, which argues for an underlying determinism in the development of community structure. The guild composition on the introduced species (Q. cerris and Q. ilex) was most closely correlated when expressed as species richness.
5. The similarity of the guild composition on the oak species in the UK in terms of the actual species found was tested by a modified Sørensen's Index. This showed that the guilds could be ranked in the following order of decreasing similarity: epiphyte fauna, tourists, scavengers, phytophages, parasitoids-predators.
6. There were distinct seasonal patterns. In terms of species richness the values showed a general trend peaking in summer and early autumn, but biomass peaked in May on the native oak species, mainly due to Lepidopterous larvae. The ratio of prey to predator and parasitoid biomass had a distinct seasonal pattern, there being an excess of prey in May, but almost an equivalence throughout the rest of the season. This may reflect the high population of spiders in the late summer and autumn, which are likely to feed on tourists. Most classical ecosystem models do not allow for this latter important source of food that is not itself dependent on the communities' habitat.
7. The epiphyte dwelling guild (principally grazing Psocoptera) was a major component of the fauna in terms of numbers on the evergreen Q. ilex in UK. This has been reported for other studies of evergreen species in temperate climates.
Species composition, structure and ecological characteristics of the vegetation of two pond types with different management, fishponds and storage ponds, in the Českobudějovická pánev basin (South Bohemia), were compared. A selection of 99 relevés from fishponds and 99 from storage ponds (small ponds used for the storage of marketable fish) made in 2000–2004 were analysed using direct and indirect ordination and ANOVA. The difference between storage ponds and fishponds was found to be more important than gradients correlated with temporal changes, soil moisture and mud depth. Storage ponds had a significantly higher mean number of species, bryophytes, archaeophytes and neophytes and beta-diversity. There were no significant differences in cover values, except of moss layer, which had significantly higher cover in storage ponds. Fishponds had significantly higher mean Ellenberg indicator values for light, continentality, moisture and nutrients. Oenanthe aquatica and Rumex maritimus are typical fishpond species and Amblystegium humile and Eleocharis palustris agg. typical storage pond species. The management of storage ponds is more varied and of different intensity than that of fishponds. It is assumed that management is a crucial factor determining the species richness and influencing the vegetation of these two habitats.
Variation with altitude in the composition of dung beetle assemblages and species richness was measured by sampling in spring, summer and autumn, both manually and with pitfall traps at twelve localities in the western Rhodopes Mountains. Non-parametric estimates indicate that most of the regional species pool was collected, some 73% of all taxa previously recorded in the entire region. The rate of species richness decrease with altitude is around 11 species per km, with an evident altitudinal change in the incidence of two main dung beetle functional groups in which Aphodiinae species begin to dominate Rhodopes assemblages at around 1400-1500 m. Species richness of dung pats is dominated by Scarabaeinae in spite of the fact that the number of Aphodiinae species is highest at each locality. Thus, Aphodiinae species are the main contributors to both local and regional pool richness and to species turnover between localities. These characteristics are similar to those observed in the assemblages from another European mountain range, also located near the Mediterranean-Eurosiberian boundary, the Iberian Central System. These results suggest that eastern European dung beetle assemblages are similar in compositional turnover and species richness variation with altitude to that observed in western Europe and North America.