Early Successions in the Floodplain of the Kamp River (Austria)

Abstract

In 2002, large riparian parts of the river Kamp in Lower Austria were affected by a flood which eradicated almost all vegetation at the riverside. From 2003 to 2012 the authors documented early stages of succession at five specific sites with characteristic vertical and horizontal distances to the river. Phytosociological releves were performed. Ecological indicator values, life traits, diversity indices (species number, evenness) and Sorensen index were used to describe the development within this period. The results demonstrate that, after five years, succession had usually reached a stage where highly competitive species like Phalaris arundinacea or Alnus glutinosa dominate. The first year after the flood annuals, lots of them common ruderals, dominated. The second year a change to biennial species took place. This transition was paralleled by a numeral maximum of species in the second year. Differences were only evident at a site where vegetation had not been completely eradicated by the flood. At this site a rudimentary stage of annuals was directly followed by an increase of Phalaris arundinacea that had been formerly present as well. Succession dynamics were stronger where conditions did not favor competitive species, which led to higher evenness values. Evenness values decreased, whenever Phalaris or Alnus achieved the dominance. As a matter of fact, these vegetation types showed a minimum in biodiversity. Maxima of evenness were found in vegetation with a high percentage of ruderals and short- living species.