Diversity of aestival plant communities of irrigated garden croplands in Cretan villages

A numerical classification of 36 relevés of the spontaneous plants occurring in irrigated garden croplands in Crete revealed three plant communities with different species combinations described here as new: Solano nitidibaccati-Amaranthetum powellii, Amaranthetum blitoidis-viridis und Digitario sanguinalis-Cyperetum rotundi.The associations show distinct local distribution patterns and differ in their ecological preferences.Similarities with and differences to other aestival plant communities of Mediterranean and Balkanic croplands are outlined.The proportion of alien species established in Cretan gardens totals up to about one third -more than in all other known plant communities in Crete.A comparison with a list of ruderal plants in the Aegean from the first half of the 20 th century suggests that the ruderal vegetation has changed a lot since, and that species of the genera Chenopodium and Amaranthus have become much more common.Such changes probably result from the expanse of irrigated croplands.