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Debrecen, Hungary

Popiela A.,University Of Szczecin | Lysko A.,Pomeranian University | Molnar A.V.,Debrecen University | Kacki Z.,Wroclaw University | Lukacs B.A.,Center for Ecological Research
Acta Botanica Gallica | Year: 2015

Elatine triandra Schkuhr is the most variable and widespread species within the genus Elatine L.; it has been recorded in all continents, except Antarctica, but it is mainly located in Europe. The study is based on an extensive data set of European literature, herbaria and web data that covers the period 1828-2012. The range of the species in Europe is disjunctive, covering the southern and western parts of the Central European Plain and the southern part of the Fennoscandian Shield. At a smaller scale, the species can also be found along some river valleys. In Central Europe many localities, particularly isolated ones in the northern part of the range, are now only historical. From the data set we determined that E. Triandra may be best observed between May and October. We found that species records show a near-significant shift since 1828. Depending on the environmental conditions, individuals of the taxon develop as one of two morphs: terrestrial or aquatic. The aquatic morph is characterized by stems, internodes, lamina and petiole that are twice as long as those of the terrestrial form. Elatine triandra seeds show consistent characteristics, both in terms of morphs and populations. Our studies show that the best diagnostic features, in addition to the construction of flowers, are the size, shape and surface structure of seeds. In Central Europe, E. Triandra occurs exclusively in communities classified as Isoëto-Nano-Juncetea. © 2015 Société botanique de France. Source


Engloner A.I.,Center for Ecological Research
Community Ecology | Year: 2015

In aquatic macrophyte ecology, species abundance is usually estimated by cover values expressed on the ordinal scale. Recently, there has been increasing demand for three-dimensional estimates of plant abundance. To extend ordinal cover data into three dimensions, a new formula is proposed which considers the vertical developmental types of plants. In this, a constant k is used with three different values reflecting three groups of macrophytes, namely the "free floating leaved"; "rooted, floating leaved" and "submersed leaved" species. By using the new formula, inappropriate conversion and evaluation of ordinal abundance data occurring frequently in the literature may also be avoided. Source


Nery T.,University of Western Australia | Nery T.,University of Basel | Schmera D.,University of Basel | Schmera D.,Center for Ecological Research
Hydrobiologia | Year: 2016

Headwater stream macroinvertebrates play an important role in processing allochthonous leaf litter, which suggests that bottom-up forces control macroinvertebrates. However, because larvae of stream-breeding salamanders are predators of macroinvertebrates and are abundant consumers in these ecosystems, macroinvertebrates in fishless headwater streams might also be controlled by top-down forces through predation by salamander larvae. The aim of this study was to test if and to what degree taxa richness, abundance, and biomass of macroinvertebrates are affected by bottom-up and top-down forces. We selected headwater streams with high abundances of fire salamander larvae (1.2–2.6 individuals per 1 m of shore length) and manipulated bottom-up and top-down forces on macroinvertebrates by leaf litter addition and by the exclusion of salamander larvae. The amphipod Gammarus fossarum Koch, 1836 was the dominant taxon and responded positively to litter addition. Linear models showed that neither predator exclusion nor leaf litter addition affected richness. However, variation in biomass and density were both explained by the individual and joint effects of bottom-up and top-down forces. These findings suggest that macroinvertebrates in these streams are strongly dependent on the organic matter input and salamander larvae, and headwater streams interact strongly with their adjacent terrestrial areas. © 2015, Springer International Publishing Switzerland. Source


Valko O.,Mta Of Biodiversity And Ecosystem Services Research Group | Tothmeresz B.,Debrecen University | Kelemen A.,Debrecen University | Simon E.,Debrecen University | And 3 more authors.
Agriculture, Ecosystems and Environment | Year: 2014

For an effective conservation and management in grasslands it is essential to understand mechanisms sustaining biodiversity. To gain knowledge is especially crucial in stressed grasslands harbouring a unique flora and fauna, like alkali grasslands. Aboveground vegetation, seed bank and environmental factors were studied in three stands of the following alkali grassland types: (i) Artemisia dry alkali grasslands at highest elevations; (ii) Puccinellia high and (iii) Puccinellia low grasslands at medium to low elevations, and (iv) Juncus wet alkali grasslands at the lowest elevations. We tested the following hypotheses: (i) Seed bank species diversity and density are the highest in the most stressed grassland types, where regeneration by seeds could have a major importance in sustaining vegetation diversity. (ii) Seed bank density of hygrophytes increases with decreasing elevation, because the cover of hygrophytes in the vegetation increases with decreasing elevation. The mean seed bank density ranged from 30,104 up to 51,410seeds/m2, which is higher than in most dry grasslands. Both the lowest seed bank density and diversity were detected in the most stressed Puccinellia high grasslands; Spergularia salina was the only abundant seed bank species (possessing at least 1000seeds/m2). These results not supported our first hypothesis. We detected the highest seed densities of almost all hygrophyte species in the lowest-elevated Juncus grasslands. But, we did not find a significant monotonous correlation between elevation and the overall hygrophyte seed bank density; because most of the hygrophyte species were missing from the seed bank at the medium-elevated, but most saline Puccinellia grasslands. Thus, our results only partly supported the second hypothesis. In total we detected more species in the seed bank than in the aboveground vegetation which emphasises that seed bank plays an important role in sustaining the diversity of alkali grasslands. However, characteristic graminoids possessed no considerable seed bank, except for Juncus compressus (up to 38,619seeds/m2). We can conclude that persistence and establishment of most alkali grassland species are not supported by the local persistent seed bank. © 2013 Elsevier B.V. Source


Boda P.,Center for Ecological Research | Borza P.,Danube Research Institute
Crustaceana | Year: 2013

In the River Tisza, the longest tributary of the Danube, Limnomysis benedeni Czerniavsky, 1882 had been the only mysid recorded until recently. In 2011, we found a few juvenile specimens of Hemimysis anomala G. O. Sars, 1907 in two daytime samples taken from the Hungarian river section. During the overnight survey in 2012 aimed at revealing the actual distribution of this nocturnally active species, its most upstream occurrence was detected at Szolnok (river km 334). Paramysis lacustris (Czerniavsky, 1882) was also found at every sampling site of the river downstream of Tiszabercel (rkm 568), representing the first record of the species for the fauna of Hungary, and its most upstream self-sustaining population in the basin of the River Danube (1759 rkm from the Danube mouth). P. lacustris is the fourth Ponto-Caspian mysid that has begun to expand its range spontaneously in the Danube catchment after L. benedeni, H. anomala, and Katamysis warpachowskyi G. O. Sars, 1893. Due to its zooplanktivory it can be anticipated to have a considerable effect on the composition and abundance of the zooplankton assemblages and it may also become an important food source for certain fish species, especially in the impounded reaches and in stagnant or slow-flowing backwaters. P. lacustris-similarly to H. anomala-shows a diel vertical migration, moving to shallow waters only by night, which calls for increased attention in order to reveal its possible future range expansions. Although the River Tisza itself is not connected directly to other river basins via canals, it may potentially contribute to the further spread of the species (e.g., via fish stocking). © 2013 Koninklijke Brill NV, Leiden. Source

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