Time influence on vegetation classification results

Vegetation classification is based on that of samples represented by relevés. If these samples are collected in different years and seasons, their composition may be affected by influence of seasonal and interannual dynamics as well as invasions. Combination of such relevés in synoptical tables may lead to formation of images of chimeric communities that do not exist in nature. Time is suggested to be a complex ecological factor similar to geographical factors such as latitude, longitude and altitude. The more dynamic phytosenoses are the shorter time frame when making relevés wich are included into synoptical tables should be. It will allow to avoid distinguishing chimeric plant combinations. Moreover, thin temporal sections will give an opportunity to reveal phytosenoses with having vanished species combinations, i.e. "extinct communities", or to state the appearance of new plant combinations. If community relevés made in the same place considerably differ in flora composition and plant abundance, they should be related to different syntaxa even if they are separated by a very short time interval. Time indication of making relevés must become a compulsory rule.