Shifts of arable plant communities after agricultural intensification: a floristic and ecological diachronic analysis in maize fields of Latium (central Italy)

Changes in agricultural practices represent one of the main causes of shift in species composition of arable plant communities. In particular, the intensification of agriculture going on worldwide since several decades led to heavy transformations of arable plant diversity. Basing on a study conducted in 1964 in Latium (central Italy), we re-surveyed the arable plant communities of 21 maize fields in order to assess the shifts that occurred over 50 years. The results showed a relevant decrease in the number of species (both in the total number and in the mean number per releve), accompanied by a major species turnover. An increase in neophyte, wide-distribution, geophyte, C4 photosynthetic pathway, and monocot species was observed, while the incidence of insect-pollinated taxa decreased. The calculation of the mean Ellenberg indicator values per releve showed an increase, in particular, of nutrients and moisture levels.