Botanikai-Természetvédelmi Folyóirat

Journal of Pannonian Botany

Kitaibelia vol. 3 – no. 2. (1998) p.331-334.

Löszgyepek és félszáraz gyepek: kompozíció, struktúra, rovar-közösségek
V. Sipos Julianna – Varga Zoltán
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Loess grasslands of the Pannonian lowland and the semi-dry grasslands of the hilly areas are compared. Loess grasslands may be regarded, at least partly, as zonal communities; they display a high species diversity and a high number of constant species. As a consequence of the high diversity, the loess grasslands are richly structured by tall-forbs and display a patchy structure of clonal forbs. The floristically richest stands are to be found in the "Mezőség" of Transdanubia, where also several species of the semi-dry grasslands occur due to the sub-mediterranean influences. Loess grasslands of the SE part of the lowland (county Békés) show the closest connection to the zonal meadow steppes and to the swards of the Transsylvanian basin. The geographically slightly differentiated association (Salvio-Festucetum) is widely distributed on the Pannonian lowland and adjacent hilly areas from the "Porta Hungarica" of the Carpathian basin to the Transsylvanian basin in the East and to the loess ridges of the Banat in the South. The successional connections of this associations are nearly linear. The meadow-steppe like semi-dry grasslands (Cirsio pannonicae - Brachypodion pinnati, Danthonio - Stipion tirsae) are widely distributed in the hilly areas surrounding the Pannonian basin. They display a very high diversity of floristic composition and they also can be phytocenologically subdivided into numerous cenotaxa. They were originally mostly semi-natural, extensively used grasslands (traditionally mowed once a year), but they have been also recently developed, as more advanced stages of old field succession, especially of old vineyards, but also of former arable lands. They are phytocenologically extremely complicated, due to their manifold origin and many transitional types, and they also display an exceptional high floristic diversity, as a consequence of the mixture of the steppe grassland, forest-steppe and forest-skirt species. Since their traditional use was discontinued, structural change occurred, resulting in an extension of polycormon and tall-forb plant species ("Versaumung" in German). Floristical and life-form composition, physiognomical structure are considered in connection to two dominant phytophagous insect groups. The microclimatically sensible, but trophically not specialized Orthoptera-assemblages reflect mostly the physiognomical structure of vegetation. They proved as good indicators of structural changes of vegetation based on quantitative relations of their well-defined life-form types. Because they are relatively unsensible on smaller-scale heterogenities of their environment, their assemblages can be easily parallelized with the plant associations. Lepidoptera are often food-plant specialized, thus their resources regularly display a patchy pattern. Hence, their meta-populations often cover a larger area which can be characterized by smaller spots of larval food-plants, stands of nectar-sources and also by a landscape-scale structure of sigma-associations. It means that they do not have a well-defined indicative value as a community, but "individually" several species can be regarded as "keystone species" of large-scale spatial patterns of vegetation. Conservation value of these swards is discussed.