Is plant community organization level relevant to monitoring landscape heterogeneity? Two case studies of mosaic landscapes in the suburban zones of Prague, Czech Republic

This paper presents the results of a vegetation monitoring project in two seminatural areas representing both recently urbanized and agricultural suburban zones of Prague undertaken between 1986 and 1992. Land disturbances imply different rates of change in the permanent plots (quadrats) under consideration, thereby enabling the vegetational component of the landscape mosaic to be monitored. Good coincidence between species richness and successional age of formations in both areas was confirmed. The dependence of species richness on the size of vegetation patch differed in various types of ecosystems. The specific role played here is probably the relative proportions of the plant dispersal strategy types in every community present in both areas. The indices of landscape heterogeneity compared over time exhibited different tendencies. Small ‘islands’ of successionally older formations seemed to be more sustainable in the landscape with a balanced regime of disturbances and with a relatively stable network of ecotones varying in successional contrast. Thus the steppe grasslands of high value for nature conservation are better protected in an agricultural landscape than in a landscape disturbed irregularly in the suburban zone with new housing estates.