Content of the Volume 32.
Horváth, A. and Makrai, L.: Variability of spatial dependence within a pioneer plant community
Molnár, N., Kovács, É. and Gallé, L.: Habitat selection of ant-tended aphids on willow trees
Krízsik, V. and Körmöczi, L. (2000): Spatial spreading of Robinia pseudo-acacia and Populus alba clones in sandy habitats. - Tiscia 32, 3-8.
Abstract. Invasion of alien species has become a general problem word-wide. Among the shrinking patches of natural vegetation, various human activities create artificial corridors for the migration of species which have been geographically separated, and have had distinct evolutionary histories. The time scale of invasions is much smaller than the evolutionary scale of the traits by which these species have been adapted to their environment. Black locust was introduced to the Hungarian Great Plain in the 19th century.
Its successful invasion nowadays seriously threatens the maintenance of natural communities over large areas, especially in sandy habitats. Our aim was to study the reasons for the rapid invasion of this species. In particular, we focused on its capacity for clonal reproduction.
We investigated the dynamics of ramet production and spatial spreading of Robinia clones in sandy habitats. In comparison, we measured the same traits in another clonal tree species, Populus alba. White poplar is an element of the natural vegetation in the same area.
Robinia proved to be more aggressive and successful in the occupation of vegetation gaps by strong establishment of brush-wood. Why is the Robinia so successful in the occupation of the sandy habitats of Great Hungarian Plain. In this respect, the ability and dynamics of clonal growth seems to be important. We hypothesise that the utilisation of vegetation gap differs in the case of a native and an adventive species
Keywords: growth
strategy, competition, invasion, black locust, white poplar.
(full text)
Szigetvári, Cs. (2000): Phytosociological and edaphyc aspects of the invasion by Cleistogenes serotina (L.) Keng in the Kiskunság National Park. - Tiscia 32, 9-17.
Abstract. In the recent decades Cleistogenes serotina, a perennial grass native to Hungary has become a successful invader in the open sand grasslands of the Great Hungarian Plain. The aim of the present study is to detect if there is any relation between the different community types, soil properties and the dominance of the invader. Plant cover as well as seven soil parameters (soil water, organic matter and carbonate content, pH, nitrate, available potassium and phosphate concentration) were studied in a transect of 139 0.5×0.5 m quadrats on a slope of a sand hill in the Kiskunság National Park, Hungary.
Three distinct vegetation types were detected: Cleistogenes-dominated type, Fumana procumbens-dominated open perennial grassland type, and Secale-dominated open annual grassland type. The invader-dominated type was in many aspects - low cover of spring annuals and criptogams, high pH, low nutrient concentration - more similar to the Fumana-type (which is close to the original natural vegetation of the habitat) than to the Secale-type (which is considered a degraded vegetation type). In the Cleistogenes-dominated quadrats soil water content was higher than in the other two types, and a slight increment in the cover of the subordinate annuals was also detected as compared to the Fumana-dominated vegetation.
Keywords:
invasion success, open sand grassland, degraded and natural
vegetation, soil conditions, transect,
(full text)
Horváth, A. and Makrai, L. (2000): Variability of spatial dependence within a pioneer plant community. - Tiscia 32, 19-29.
Abstract. Since it is important to know the degree of variability of spatial dependence among plant populations when comparing two communities, but only a very few literature data exist on it, the first aim of this study is to give some compensation for this deficiency. We applied information statistical models to estimate vegetation pattern organization in an early stage of primary succession, and computed associatum values and their variances along the spatial scale. The null model was the random shift, the validation procedure was also executed for it. We can summarize, that the sampling area with 50:m2 was sufficiently large to gain interpretable associatum curves. The area of maximum spatial organization was 15:cm:´:15:cm, which significantly differs from null model. When we divided the whole sampling area to 10:m2 stripes, the associatum difference curves of every parcels had significant interval, and average of them was similar to the curve from the whole area. Therefore, a 10:m2 area could represent the unit of entire community. When the area was decreased to 2.5:m2, the variability of spatial dependence increased, and the appearance of significant associatum values became more unpredictable. At this size of area the unity of patterns organization seems to be collapsed, and the samples can not represent effectively the entire community. Six types of associatum measures were compared regarding to their variability in the spatial series steps.
Keywords:
information theory models, syncretic functions, spatial
dependence, spatial scaling, primary succession, randomization
tests, validation of null models
(full text)
Molnár, N., Kovács, É. and Gallé, L. (2000): Habitat selection of ant-tended aphids on willow trees. - Tiscia 32, 31-34.
Abstract. We studied the spatial distribution of aphid populations as a function of host plant's properties and the ant species associated with them on dispersed willow trees (Salix alba) in the flood area of river Tisza. Our data based on the examination of 63 trees, 10 shoots on each. The presence of tending ants on willows promotes the maintenance of the aphid species diversity. The density of aphid populations were also positively influenced by the mutualists (mainly by Lasius fuliginosus). The relationships between the different aphid species and ants were various: Chaitophorus vitellinae showed stronger mutualistic interaction, than Pterocomma species. We have not experienced competitive interactions between aphid populations for services of ants. The different tree attributes had no significant influence on the habitat selection of aphids. Spatial distribution of aphids was affected by both the presence of ants and their number.
Keywords:
aphids, ant-aphid mutualism, spatial distribution,
ant-attendance, competition
(full text)
Alvarado, M. (2000): Habitat correlates of ant assemblages in different forests of the South Pannonian Plain. - Tiscia 32, 35-42
Abstract. Ant assemblages and their potential habitat correlates were studied in 20 forests of different tree composition (oak, poplar, juniper, black locust, pine, Russian olive and hybrid poplar), age, state of isolation and anthropogenic disturbance. The forests were characterized with 148 habitat scores, grouped in five: vegetation architecture, vegetation composition, microclimate, soil properties and the number, the condition and the size of the twigs on the ground surface. A non-parametric correlation analysis was carried out between the configuration of the observed habitats in principal coordinate factor spaces obtained on the basis of their ant assemblage composition and the different groups of habitat scores. Significant correlation was revealed between ant assemblages and vegetation architecture, vegetation composition and the twigs on the ground surface. Another computation of correlation between single habitat scores and the axes of PCoA factor space of ant assemblages showed that ants correlated with vegetation cover at 5 cm height, with the average tree diameter, with all the measured parameters of twigs and with the soil pH.
Key words: ant
communities, native and planted forests, habitat conditions
(full text)
Tartally, A. (2000): Notes on the coexistence of the supercolonial Lasius neglectus van Loon, Boomsma et Andrásfalvy 1990 (Hymenoptera: Formicidae) with other ant species. - Tiscia 32, 43-46.
Abstract. Lasius neglectus is an invasive species known for about ten years. This species excludes other ant species from the areas of its supercolonies and causes much trouble for people by intruding to their houses. Apart from these, there is not much we know about the ecology of L. neglectus. The aim of my paper is to compare ant communities living in the border and in the centre of the L. neglectus colonies. As my experiences show L. neglectus reaches a quite high abundance in the centres of the supercolonies at the expense of the abundance of other ant species. It was proved using the c2 test, that the distribution of the L. neglectus in the centre area and the border was significantly different (p<0.95). We have also demonstrated that the Shannon diversity of the centre assemblage is significantly smaller than the diversity of the border (p<0.95). This can be explained by the polygynous strategy, which is characteristic for Lasius neglectus.
Keywords:
Lasius neglectus,
supercolony, colony formation, ant communities, coexistence,
aggression
(full text)
Horváth, Gy. (2000): Comparative analysis of the small mammal fauna of the River Drava plain region. I. Species richness, diversity and biomass based on the analysis of Barn owl Tyto alba (Scop., 1769) pellets. - Tiscia 32, 47-54.
Abstract. A total of 2176 pellets and pellet fragments were analysed, all of which have been collected in 15 human settlements along the river Dráva, during 1996. From these 4335 small mammal specimens were identified. Among the Insectivora, six shrew species belonging to the family Soricidae and four insectivorous genera were identified, whereas among the rodents (Rodentia) 12 species were differentiated plus one genus-level (Apodemus spp.) identification was made. With the help of abundance data of the small mammal taxa identified from the pellets, a significant saturation curve was found to exist between sample size and number of species. With the increase of pellet number, the number of species did not change considerably. Shannon-diversity and evenness were not sensitive to sample size, but Margaleff's species richness values significantly decreased as the number of pellets increased. As a result of differences in sample sizes, the small mammal communities in only 9 of the settlements were compared using cluster analysis and variance analysis. I concluded from the results that several years of data collection is necessary to clearly describe the small mammal species composition of the studied region.
Keywords: small
mammal diversity, species richness, biomass, pellet analysis,
Tyto alba
(full text)
Teodorovic, I., Djukic, N., Maletin, S., Miljanovic, B. and Jugovac, N. (2000): Metal pollution index: proposal for freshwater monitoring based on trace metal accumulation in fish - Tiscia 32,55-60.
Abstract. Different fish species (benthivore and piscivore) from the Channel System Danube - Tisza - Danube in Yugoslavia have been analysed for body trace metal burden with an aim to establish freshwater metal pollution biomonitoring. New Metal Pollution Index (MPI) which distinguishes polluted from unpolluted ecosystems is proposed, based on acquired knowledge on metal bioavailability, bioconcentration and bioaccumulation patterns. This simple mathematical model is calculated upon logarithmically transformed values of metal concentrations in fish tissue, in order to achieve normal distribution of the element values and to diminish the more than thousand-fold differences between the least and the most abundant elements. MPI is the simplest way which enables presentation of all results from the metal concentrations as one value, by using a normalizer (reference values for lower part of the Danube Basin) to account for biological variation in non-polluted areas. Since no biomagnification within fish trophic chain has been observed, benthic fish seem to be, due to the highest metal burden, more suitable for evaluation. Furthermore, Carassius auratus gibelio, being presently one of the most abundant species inhabiting the Yugoslav part of the Danube watershed is being proposed as sentinel organism.
Key words: trace
metals, Metal Pollution Index, freshwater monitoring, fish,
Danube Basin
(full text)