Zmiany roślinności segetalnej Równiny Piotrkowskiej w ostatnich 22 latach. Część I. Zbiorowiska chwastów upraw zbóż ozimych [Changes of segetal vegetation of the Piotrków Plain during the last 22 years. Part 1. Communities of weeds of winter cereal cultures]

This paper presents the results of research in segetal communities of winter cereal cultures of the Piotrków Plain (Figure 1) which took place during the period between 1971 and 1972 and between 1992 and 1993. On the basis of 205 phytosociological records, taken in 103 localities in the years of 1971 and 1972 (Figure 2), 6 associations were distinguished (Tables I–IX): Spergulo-Veronicetum dillenii, Arnoserido-Scleranthetum, Papaveretum argemones, Vicietum tetraspemae, Aphano-Matricarietum, Caucalido-Scandicetum. According to the repeated listing carried out in the years 1992 and 1993 the changes of the communities of the mentioned items were disclosed. The comparison of the present state of the weed communities of the winter cereal cultures on the researched area with the state of 22 years ago allowed to note that the changes in the analyzed agrophytocoenoses are caused by progressive anthropopressure