J. Házi

Seminatural grassland management by mowing of Calamagrostis epigejos in Hungary.

Abstract Regeneration of seminatural grasslands are often threatened by the invasion of Calamagrostis epigejos, which can slow down or arrest secondary succession. Here we report the results of a 9-year mowing experiment designed to suppress the spread of C. epigejos in mid-successional grasslands in Hungary. The experimental design consisted of 16 permanent plots of 3 × 3 m. Half of the plots were mowed twice a year (in June and September), the other half was left as control. Vegetation was sampled in 2 × 2 m quadrates before mowing in each year between 2001 and 2009. The effects of mowing were tested using repeated–measure analyses of variance (ANOVA) and Tukey HSD for post hoc tests. Significant decrease of C. epigejos appeared after 2 years of mowing. Species richness increased after 4 years, while diversity after 8 years. By this time the target native species Brachypodium pinnatum become dominant. Similar trends appeared in the control plots during spontaneous succession but at much slower rates. Our results suggest that C. epigejos disappears spontaneously in secondary grassland succession after ca. 40–50 years. However, mowing twice a year can speed up this process by opening a “colonization window” to the valuable target species. For successful control, mowing should be maintained for approximately 8 years.

Grazed Pannonian grassland beta-diversity changes due to C 4 yellow bluestem

This study investigates how yellow bluestem affects biodiversity in a typical Pannonian grassland. Beta diversity (i.e. the finescale spatial variability of species compositions), was estimated by the realized number of species combinations sampled at various scales. Sampling was performed by a standard protocol. Presences of plant species were recorded along 52.2 m long belt transect of 1044 units of 0.05x0.05 m contiguous microquadrats. According to the results the massive presence of tested C4 grass significantly reduced species richness of the grassland. Beta diversity assessment revealed that 90% of species combinations were lost due to yellow bluestem invasion. Fine-scale spatial pattern analyses showed complete local extinctions of other species from microsites dominated by yellow bluestem. This local extinction is enhanced by the specific clonal architecture of this species and by the accumulation of litter. Other dominant grasses had no effect on fine scale diversity, i.e. they could coexist well with other elements of the local flora. This study presents currently developed microhabitat types, forecasts and also draws attention to the danger that climate warming will probably enhance the spread of this detrimental C4 species.

Evaluating alternative mowing regimes for conservation management of Central European mesic hay meadows: A field experiment

Abstract Conservation status of hay meadows highly depends on their management. The main goal of this study was to assess the efficiency of different mowing regimes in maintenance of plant species richness and diversity of mesic hay meadows. The field experiment was carried out on a species rich, mesic hay meadow in Western Hungary. We evaluated the effects of four alternative types of management on the plant community after 7 years of continuous treatment: (1) mowing twice a year, typical traditional management, (2) mowing once a year in May, most practised currently by local farmers, (3) mowing once a year in September, often proposed for conservation management and (4) abandonment of mowing. Traditional mowing resulted in significantly higher number and higher diversity of vascular plant species than other mowing regimes. Mowing twice a year was the only efficient way to control the spread of the invasive Solidago gigantea, and mowing in September was more successful in it than mowing in May. We conclude that the traditional mowing regime is the most suitable to maintain botanical diversity of mesic hay meadows; however, other regimes should also be considered if certain priority species are targeted by conservation.

Filtering effect of temporal niche fluctuation and amplitude of environmental variations on the trait-related flowering patterns: lesson from sub-Mediterranean grasslands

Timing of flowering is a critical component of community assembly, but how plant traits respond to heterogeneity of resources has been identified mostly through observations of spatial variations. Thus, we performed a trait-based phenological study in sub-Mediterranean grasslands to assess the importance of temporal variation of resources in the species assemblage processes. We found that early flowering species have traits allowing for slow resource acquisition and storage but rapid growth rate. Instead, mid- and late-flowering species exhibited sets of strategies devoted to minimizing water loss by evapotranspiration or aimed at maximizing the species’ competitive ability, thanks to slow growth rate and more efficient resource acquisition, conservation and use. Our findings were consistent with the fluctuation niche theory. We observed that the amplitude of the environmental fluctuations influences the type and number of strategies positively filtered by the system. In fact, in the most productive grasslands, we observed the highest number of indicator trait states reflecting strategies devoted to the storage of resources and competition for light. Results seem also indicate that temporal variation of resources plays a role in trait differentiation and richness within a plant community, filtering traits composition of grasslands in the same direction, as formerly proved for spatial heterogeneity of resources.

Wet habitats along River Ipoly (Hungary) in 2000 (extremely dry) and 2010 (extremely wet)

This study presents habitat maps from two years in which precipitation was extreme – 2000 was one of the driest years while 2010 was one of the wettest years in the Carpathian Basin. The study area is in northern Hungary, beside the River Ipoly, in the municipality of Drégelypalánk, with a smaller proportion in Hont and Ipolyvece. Its extent is 621.5 hectares. During the field survey habitat polygons were recorded using a hand-held GPS device, with aerial photographs helping to identify the exact location. Processing of the data, establishment of a database of the mapped area, and editing of maps were performed using ESRI ArcView GIS 3.2 and ESRI ArcGIS 10.0. The maps, at a scale of 1:15,000, show vegetation and habitats of the study area. They display changes occurring within habitats, in habitat types determined by their nature, composition and changes that occurred along their polygon borders. Large vegetation changes caused by the changes in precipitation over the time period can be tracked with the maps which display habitat changes. The area of wetlands increased significantly, whilst areas of meadow and marsh decreased and in their place new complex aquatic habitat forms appeared. The number of habitat complexes also increased because of the presence of water linked to habitat types and fragments. In the humid period, a sustained floodplain groundwater-level increase was observed that resulted in a mosaic appearance in habitats, but led to species degradation.