Authors:G. Ónodi, V. Altbäcker, R. Aszalós, Z. Botta-Dukát, I. Hahn and M. Kertész
Bartha, S., G. Campetella, E. Ruprecht, A. Kun, J. Házi, A. Horváth, K. Virágh and Zs. Molnár. 2008. Will interannual variability in sandgrassland communities increase with climate change? Comm. Ecol. 9: 13
. (2000): Changes of composition of sandgrasslands along a climatic gradient in Hungary and implications for climate change. - Phytocoenologia 30 : 385-407.
Changes of composition of sandgrasslands along a climatic gradient in
Authors:D. Vodnik, I. Maček, E. Péli, U. Videmšek and Z. Tuba
Z. Tuba. 2004. Botanical composition and some CO
exchange characteristics of temperate semi-desert sandgrassland in Hungary under present-day and elevated air CO
We studied biomass and species composition changes of open perennial sand grassland (
) as response to different levels of simulated grazing pressures. We conducted a factorial micro-plot field experiment on previously grazed grassland that has been abandoned for a long time. In a two-way factorial design of 12 treatments × 8 repeats, we performed clipping (twice a year for three years) and litter treatments (removing and adding litter once at the beginning of the experiment) to simulate components of grazing, namely the biomass removal and the reduction of the litter accumulation. We used field spectroscopy and visual canopy cover estimation to measure the effects on the amount of the above-ground green biomass and on the vegetation composition.
The influence of elevation and vegetation characteristics on the spatial pattern of an epigeic true bug assemblage was investigated along a transect in a sandy grassland of Kiskunság. A 55 m long transect through wind grooves and dune tops, perpendicular to the vegetation borders was established. Both the moving split window technique and the ordination method revealed that dune top habitat has a distinct Heteroptera assemblage. This sand dune habitat was characterized by the most abundant Heteroptera species. We did not observe a distinct true bug assemblage in the wind groove habitat. Canonical correspondence analysis and multiple linear regressions showed that the relative altitude had a greater effect on the distribution of true bugs than vegetation cover and plant species richness.
Authors:F. Samu, F. Kádár, G. Ónodi, M. Kertész, A. Szirányi, É. Szita, K. Fetykó, D. Neidert, E. Botos and V. Altbäcker
Recent environmental and land use changes have made wildfires more frequent in natural habitats of the Kiskunság Sand Ridge on the Hungarian Plain. In a study initiated 2.5 years after an extensive fire that destroyed half of the area of a sand grassland — juniper, poplar forest steppe habitat, we assessed the effects of fire on two generalist arthropod groups: spiders and carabid beetles, as well as on the vegetation. Utilizing the natural experiment situation, samples were taken by pitfalls and suction sampling during a 1.5 years period in four 1 ha blocks, two of which were on the burnt part of the habitat, and two in the unburnt control. At the time of the investigation, in the burnt area the vegetation in the grass layer showed a quick but not complete recovery, while the canopy layer of the juniper bushes burnt down with no sign of regeneration. Carabid beetles and spiders showed differences in recovery after fire. In the carabid assemblages of the burnt parts — compared to the unburnt control — there were over three times more beetles, out of which significantly more represented the macropterous life form and granivorous feeding strategy. There was a higher ratio of pioneer species and a simplified assemblage structure in the burnt area, which meant that the conservation value of the carabid assemblage became lower there. In contrast, for the spider assemblage quantitative changes in abundance and species numbers were not significant, and the differences in species composition did not lead to a decrease in conservation value. Spider species in the burnt plots could not be described as pioneer species, rather they had ecological characteristics that suited the changed vegetation structure. Comparing the two groups, to repopulate the burnt areas, dispersal abilities proved to be more limiting for carabids. However, in both groups a strong assemblage level adaptation could be observed to the postfire conditions. In spiders, species with a stratum preference for the grass layer prevailed, while in carabids individuals with granivore strategy gained dominance. Thus, despite the differences in their speed, basically both assemblages tracked vegetation changes. The effect of future fires will depend on their scale, as well as land-use practices, such as grazing, that interact with fire frequency and recovery. If extensive fires in the future permanently change the vegetation, then it would also lead to a fundamental change in the arthropod fauna.
Natural habitat edges are known to influence the vegetation structure, the microclimate and thereby the invertebrate assemblages. We studied the spiders of two forest edges in the forest-steppe zone of the Great Hungarian Plain (Site 1: a dense juniper shrub — open grassland and Site 2: a juniper and poplar forest — open grassland edge, respectively). The spider assemblages were sampled with pitfall traps arranged in 5 × 20 grid at the habitat edges. Observed and estimated species richness was higher for the grasslands than for the forests. Renyi’s diversity ordering was applied to compare species diversity. The results showed that the grasslands were more diverse in terms of spider species than the forests. The composition of spider assemblages was significantly different between the two habitat types. At Site 2, a higher number forest specialists penetrated into the grassland. Presumably this was due to the shading effect of the nearby poplar trees. Constrained ordinations also revealed a strong influence of the neighbouring poplar trees and vegetation structure on the spider assemblages. No exclusively edge associated species were found on either of the two sharp forest edges.
Authors:M. Biró, K. Szitár, F. Horváth, I. Bagi and Zs. Molnár
Bartha, S., Zs. Molnár and G. Fekete. 2008. Patch dynamics in sandgrasslands: connecting primary and secondary succession. In: E. Kovács-Láng, E. Molnár, Gy. Kröel-Dulay and S. Barabás (eds.), The KISKUN LTER, Long-term Ecological Research in the