Changes of segetal vegetation of the Piotrków Plain during the last 22 years. Part II. Communities of weeds of flax and root crop cultures

This paper presents the results of research on changes in segetal communities of flax and root crop cultures of the Piotrków Plain (see W a r c h o l i ń s k a, 1994 - Figure 1) which took place during the period between 1971 and 1972 and between 1992 and 1993. On the basis of 72 phytosociological records, taken in 50 localities (Figures 1, 2) in the years of 1971 and 1972, 5 associations were distinguished: one in the flax culture (Table I) - Spergulo-Lolietum remoti and four in the root crop cultures (Tables II-V) - Digitarietum ischaemi, Echinochloo-Setarietum, Galinsogo-Setarietum and Lamio-Veronicetum politae. According to the repeated listing carried out in the years of 1992 and 1993 the changes in the communities of the above - mentioned items were stated. The comparison of the present state of these communities with their state of 22 years ago allowed to note that the changes of the analyzed agrophytocoenoses of flax and root crop cultures are caused by progressive anthropopressure