Forest herb colonization of postagricultural forests in central New York State, USA

1 The recovery of forest vegetation following abandonment of agriculture wa s followed by surveying forest herbs in central New York State at 25 sites where postagricultural forest occurred directly adjacent to old-woods (fore st that has never been ploughed). 2 The abundance, richness and diversity of 50 forest herbs were on average lower in postagricultural forests than in old-woods. 3 Thirty of 39 forest herbs that were found in at least four stands were le ss frequent (number of plots present out of 60) in postagricultural forests than in old-woods. Three species (Aster divaricatus, Dryopteris intermedia and Polystichum acrostichoides) had significantly higher frequency in old- woods, while none was significantly more common in postagricultural forests . 4 Although differences among species in their frequency in the two forest t ypes were not strongly related to dispersal mode, species with rapid clonal expansion were significantly more frequent in postagricultural stands. 5 Several species that were less frequent in postagricultural forests than in old-woods showed decreases in density in postagricultural forests with i ncreasing distance from the adjacent old-woods.