2013. május 29., szerda
2013. május 27., hétfő
Szivák et al. (2013) Fundamental and Applied Limnology
Abstract
The spatial variability of Chironomidae larvae assemblages was investigated at 6 near-pristine, temperate headwaters in Hungary. Sites were located within a relatively small mountain range but belong to two different catchment areas characterized by highly variable abiotic conditions. We hypothesised there would be differences in taxonomic composition but not in functional composition between different catchment areas and aimed to assess the primary influencing spatial factors structuring the taxonomic and functional compositions of chironomid assemblages. The spatial distribution of chironomid assemblages was examined 4 times during a 1 year period at microhabitat to catchment scales. At each site, streambed morphology, physicochemical attribute, riparian vegetation, microclimate and hydrology data were collected. Three main traits (saprobic preference, stream zonation preference, functional feeding groups) were used to characterize the functional composition of chironomid assemblages. Sharp differences were detected in taxonomic composition between the two sides of the mountain range within a relatively small spatial distance and moderate, but statistically significant differences in functional composition between catchments. The observed spatial changes in taxonomic and functional composition of midges accompanied changes in physicochemical characteristics, riparian vegetation, microclimate and altitude. Internal microhabitat heterogeneity also played a major role in structuring the taxonomic and the functional patterns of chironomid assemblages.
Keywords
headwater Chironomidae, small mountain range, habitat heterogeneity, spatial variation, taxonomic and functional composition, multivariate approaches
2013. május 4., szombat
Takács A. et al. (2013) Preslia
Takács A., Schmotzer A., Jakab G., Deli T., Mesterházy A., Király G., Lukács B. A., Balázs B., Perić R., Eliáš P. jun., Sramkó G., Tökölyi J. & Molnár V. A. (2013): Key environmental variables affecting the distribution of Elatine hungarica in the Pannonian Basin. – Preslia 85: 193–207.
Abstract
Elatine hungarica Moesz is a small wetland ephemerophyte that occurs and is classified as extinct, data deficient or a very rare and endangered taxon in most countries in eastern and central Europe. Based on literature and herbarium data, supplemented by 160 field records collected between 1998 and 2011, we present the currently known distribution of this species in the Pannonian Basin, which mostly but not exclusively includes Hungary. Within the Pannonian Basin this species is distributed throughout Hungary, with sporadic occurrences in Romania, Serbia and Slovakia. The temporal distribution of floristic records is very uneven. This species was recorded only in 27 years during the last 213 years (1798–2011). When examining presence/absence data for most of the 20th century, we found a significant correlation between the number of records of this species in a given year and two key, but not independent, environmental variables: rainfall and the extent of the area inundated in the same year. In the more intensively documented period between 1998 and 2010, there is only a significant correlation between the numbers of records of this species and the extent of flooding, which is because there is a delay in the effect of an increase in rainfall. The peak occurrence of records in the 1940s and 1950s is associated with extensive rice production in Hungary. Today, most records are for agricultural fields that are subject to flooding and becoming temporary wetlands. The comparison of recent and past distributions of E. hungarica reveals a consistent and marked regional difference; whereas this species is not rare along the Tisza river and its tributaries, it is markedly scattered in similar habitats near the Danube.
Keywords
ephemerophyte, flooding, Hungary, inland water, Isoëto-Nanojuncetea, Elatinaceae, mapping, rainfall, rice weeds, Romania, Serbia, Slovakia, temporary ponds
Abstract
Elatine hungarica Moesz is a small wetland ephemerophyte that occurs and is classified as extinct, data deficient or a very rare and endangered taxon in most countries in eastern and central Europe. Based on literature and herbarium data, supplemented by 160 field records collected between 1998 and 2011, we present the currently known distribution of this species in the Pannonian Basin, which mostly but not exclusively includes Hungary. Within the Pannonian Basin this species is distributed throughout Hungary, with sporadic occurrences in Romania, Serbia and Slovakia. The temporal distribution of floristic records is very uneven. This species was recorded only in 27 years during the last 213 years (1798–2011). When examining presence/absence data for most of the 20th century, we found a significant correlation between the number of records of this species in a given year and two key, but not independent, environmental variables: rainfall and the extent of the area inundated in the same year. In the more intensively documented period between 1998 and 2010, there is only a significant correlation between the numbers of records of this species and the extent of flooding, which is because there is a delay in the effect of an increase in rainfall. The peak occurrence of records in the 1940s and 1950s is associated with extensive rice production in Hungary. Today, most records are for agricultural fields that are subject to flooding and becoming temporary wetlands. The comparison of recent and past distributions of E. hungarica reveals a consistent and marked regional difference; whereas this species is not rare along the Tisza river and its tributaries, it is markedly scattered in similar habitats near the Danube.
Keywords
ephemerophyte, flooding, Hungary, inland water, Isoëto-Nanojuncetea, Elatinaceae, mapping, rainfall, rice weeds, Romania, Serbia, Slovakia, temporary ponds
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