Spontaneous vegetation succession in human-disturbed habitats: A pattern across seres

Vegetation samples from 15 successional seres in various disturbed habitats in the western part of the Czech Republic were analysed to detect possible trends. For particular seres, data on species cover were available from the onset to 10- 76 yr of succession. All seres started on bare ground. Species which attained at least 1% cover in any sere in any year were used as input data for Canonical Correspondence Analysis, assessing the effect of time as the environmental variable, for Detrended Correspondence Analysis and TWINSPAN classifi- cation. Two distinct groups of seres were distinguished: 'ruderal', occurring in agricultural, industrial or urban landscapes altered by men, usually on fertile sites; and 'non-ruderal', occurring in less altered, mostly forested landscapes, usually on acid, nutri- ent-poor and wetter soils. The former type of succession starts with ruderal annuals, being followed by ruderal perennials. In the latter case non-ruderal clonal perennials prevail from the onset of succession. The landscape frame is emphasized, beside site environmental conditions, as influencing the type of succes- sion. The character of species attaining dominance in succes- sion, participation of dominant woody plants and the character of late successional stages, i.e. features important from the point of view of potential restoration of human-disturbed habitats, are discussed.