Weed community in artificial irrigation channels of the São Francisco River Valley, Brazilian semiarid region

The aim of the current study is to perform a phytosociological survey along the irrigation canals of Senator Nilo Coelho Irrigation District, Petrolina County-PE, Brazil. Sampling procedures have followed the square inventory methodology, based on collected data about plant populations found on the canal banks and inside it (slope and center). Individuals selected to calculate parameters, such as frequency, density, abundance and importance value index (IVI), were counted. Thirty-one (31) species were catalogued on the canal banks, whereas 18 were catalogued inside the canal. Six (6) of these species were found in both environments. Turnera subulata Sm. and Cenchrus ciliaris L. were the most important species found on the canal banks (IVI = 20.6% and 13%, respectively). Terrestrial/aquatic species Ischaemum rugosum Salisb. (24.5%) and Eleocharis sp. (15.8%), aquatic species Egeria densa Planch. (16.7%) and soil algal species Chara sp. (20.7%) were the most significant ones found inside the canals. Identifying the main species and understanding their biological features enable making accurate decisions about canals’ monitoring, control and maintenance processes.