Anikó Csecserits

Regeneration of sandy old-fields in the forest steppe region of Hungary

Abstract Abandoned agricultural fields are potential sites for the regeneration of natural vegetation, and land abandonment is a widespread phenomenon in the developed world. We studied the vegetation of 161 old-fields in the Kiskunság, central Hungary. Old-fields were categorized into three age groups based on historical aerial photographs: fields abandoned 1–7, 8–20, and 21–57 years ago. Old-field vegetation was compared to potential target communities (open and closed grassland and forest) based on the richness and cover of predefined species groups (all species, neophytes, characteristic species of natural habitats). In general, the medium- and old-aged old-fields only slightly differed from each other, and were more similar to open natural grasslands than to closed ones, although they occupied environments that were intermediate between open and closed grasslands. Forest species establishment was limited in the old-fields; therefore, forest regeneration seems to be unlikely on old-fields at a decadal time scale. The dominance of alien species only slightly declined with old-field age and was much higher than in natural grasslands. The finding that open grassland communities recovered on these old-field sites, but were accompanied by stable alien components, suggests that these communities could be regarded as a new combination of species, or novel communities, with a considerably high conservation value.

The potential of common ragweed for further spread: invasibility of different habitats and the role of disturbances and propagule pressure

The infilling of existing suitable habitats within a landscape after establishment is of critical importance for the final outcome of a plant invasion, yet it is an often overlooked process. Common ragweed, Ambrosia artemisiifolia, is an invasive annual species in Europe causing serious problems due to its highly allergenic pollen and as an agricultural weed. Recent studies have modelled the broad-scale distribution of the species and assessed future invasion risk, but for predicting the expected outcome of ragweed invasion we also need a mechanistic understanding of its local invasion success. We conducted a field experiment to investigate the invasibility of eight common non-arable habitat types and the role of soil disturbance in central Hungary, in the hot spot of ragweed invasion in Europe. Seed addition alone resulted in negligible amount of ragweed biomass, except for sites where disturbance was part of the present management. Soil disturbance alone resulted in ragweed at those few sites where ragweed seeds were present in the seed bank, related to farming in recent decades. When disturbance and seed addition were combined, ragweed emerged in all habitat types and reached high biomass in all habitat types except for closed forests. As our experiment showed that most habitat types have high invasibility when disturbed, we conclude that ragweed has a high potential for further spread, even in this heavily infested region. Management should focus on preventing seed dispersal and eradicating establishing populations where ragweed is still absent, while reducing soil disturbance may be needed to avoid ragweed emergence in infested sites. This latter may require a reconsideration of land-use practices in infested regions.

Regional Vegetation Database of Kiskunság

The aim of the Regional Vegetation Database of Kiskunsag (GIVD ID EU-HU-001) was to study the effect of different land-use on plant biodiversity. The Kiskunsag region is a highly heterogeneous cultural landscape in central Hungary, with unique natural values, high diversity of land-use, its own well-defined environmental problems, and ongoing socio-economic changes, thus being an ideal setting for conducting integrative socio-ecological research and setting up an LTSER platform. In the past few years, we expanded the KISKUN LTER program into a broad-scale research framework or LTSER program by (1) covering all major landuse/habitat types occurring in the region; (2) reaching regional representativity by having multiple sites. Within the 7,500 km2 study region, using a pre-defined algorithm we selected a network of 16 sites (5 x 5 km) that covers the regional variability in land-use pattern, naturalness, and soil. We sampled three replicate stands (if available) of all major habitat types (arable land and vineyards, oldfields, natural grasslands and woodlands, forest plantations) in all 16 sites between 2006 and 2008. In a total of 604 plots (20 x 20 m) we detected the plant species present and estimated their cover.