THE ROLE OF PANICUM-VIRGATUM (SWITCH GRASS) IN THE REVEGETATION OF IRON-MINE TAILINGS IN NORTHERN NEW-YORK

We investigated the role of artificially introduced Panicum virgatum ( switch grass) on the sequential natural revegetation of 15- and 35-yea r-old tailings in the Adirondack region of: northern New York. Switch grass covered approximately 48% of the 15-year-old Chaumont Tailings. Establishment of switch-grass stands improved the fertility of the sit e by adding organic matter, raising pH, and elevating cation exchange capacity and concentrations of major nutrients (N, P, and K). Switch-g rass stands also aided the initial recruitment of such pioneer species as Populus spp. (aspens), Salix spp. (willows), and Betula spp. (birc hes). This facilitation of recruitment of woody species is explained a s follows: (1) robust switch-grass stands physically captured the wind -disseminated seeds of these species; (2) switch grass acted as a ''nu rse crop'' for these species, thus these species were able to increase their density vigorously through root or stem sprouting; (3) a combin ation of both. Switch grass decreased its cover (14%), however, as obs erved in the 35-year-old South Tailings. As switch grass declined, suc h vigorous ''root-suckering'' species as aspens increased in dominance , followed by the invasion of Prunus pensylvanica (pin cherry).