Changes in tree species composition in unmanaged floodplain forests (period 1: 1997 to 1999 – period 2: 2013 to 2014) using the angle count sampling method (Bitterlich, 1984). Average stem number per hectare in floodplain forests alongside the river March on 64 sample plots in 6 NFR in period 1 (light green) and period 2 (dark green); error bars denote standard errors. The large error bars indicate a low number of plots with a high increase in stem number for A. negundo. Ulmus spp. includes U. glabra, U. minor und U. laevis; Tilia spp. includes T. cordata, T. platyphyllos and T. × vulgaris; Quercus spp. includes Q. petraea, and Q. robur; Populus spp. includes P. alba, P. canescens, P. tremula, P. nigra, and P. × canadensis; Salix spp. includes S. alba, S. fragilis and S. × rubens.