Erdős et al. (2014) Ecological Complexity

L. Erdős, Cs. Tölgyesi, M. Horzse, D. Tolnay, Á. Hurton, N. Schulcz, L. Körmöczi, A. Lengyel, Z. Bátori: Habitat complexity of the Pannonian forest-steppe zone and its nature conservation implications. Ecological Complexity, in press, DOI: http://dx.doi.org/10.1016/j.ecocom.2013.11.004

Abstract

Eurasian forest-steppes are among the most complex ecosystems in the northern temperate zone. Alternating forest and grassland patches form a mosaic-like landscape, stretching in a stripe from eastern Europe almost to the Pacific coast. Although the edges (contact zones between woody and herbaceous vegetation) may play an important ecological role, their study has been neglected in the forest-steppes. In this study, we aimed to perform a comprehensive analysis on the components of a sandy forest-steppe in the Pannonian ecoregion (Hungary), with special regard to the edges. 2 m × 1 m coenological relevés were made in forest interiors, in edges and in grassland interiors. We carried out microclimate measurements in each habitat type. Compositional and structural characteristics of the forests, edges and grasslands were compared, including species number, Shannon diversity, summarized cover, life-form and geoelement spectra. Diagnostic species for each habitat type were identified, and the role of the habitats in harbouring protected and endemic species was also assessed. Based on the frequencies and cover values of tree seedlings and saplings in the three habitat types, we formulated tentative assumptions on vegetation dynamics. We found that edges possessed their own distinct species composition, having a considerably higher species number, Shannon diversity and vegetation cover than habitat interiors. Edges hosted relatively large numbers of edge-related species, and proved to be highly different from habitat interiors with regard to life-form and geoelement spectra. It seemed that the spatial interaction of two neighbouring communities resulted in the emergence of a third, unique community, the edge. The microclimate of the forests and the grasslands differed strikingly, whereas that of the edges fell between them. Except Populus alba, trees had very few seedlings and no saplings, which may have serious consequences if the current warming and drying trend continues. We conclude that in the study area, intermediate microclimate of the edges supports a community that is not intermediate compositionally and structurally: the edge should be recognized as a distinct community, although strongly connected to the neighbouring communities. As a consequence, forest-steppes have three integral components: forest, grassland and edge. Our results emphasize the conservation importance of all components. The conservation value of the sandy grasslands has long been recognized, but the contribution of edges and forest patches to species and habitat diversity should not be neglected either. Conservation activities should focus on maintaining the complexity of the forest-steppe ecosystem, with all of its integral components.

Keywords

Diversity, Edge, Endemic plants, Microclimate