Cool-season turfgrass colony and seed survival in a restored prairie
Nonnative cool-season turfgrasses are sometimes considered to be invasive species in restored prairies. The method of their invasiveness is poorly understood, as in many cases prairie restoration projects occur where the grasses were formerly planted. Colonies of 10 turfgrass species were placed into two anthropogenic prairies and monitored over a 2-yr period. Colonies of most species, including Kentucky bluegrass (Poa pratensis L.), creeping bentgrass (Agrostis stolonifera L.), and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort = Lolium arundinaceum (Schreb.) Darbysh.., formerly Festuca arundinacea Schreb. var. arundinacea], decreased in size or died due to herbivory and environmental stresses. At one location, fine fescues (Festuca spp.) and colonial bentgrass (A. capillaris L.) colonies remained relatively constant or slightly increased in size, while native velvet bentgrass (A. canina L.) nearly tripled in diameter. A second study compared the seed survival of six turfgrass and three native grass species at the same sites. Germination and dormancy tests were conducted following exhumation at 6, 12, and 22 mo. All the turfgrass seeds, with the exception of tall fescue, retained better viability (12–34%) than native grasses (0–1%) after 22 mo in the soil. Our results indicate that nonnative turfgrasses may be poor competitors in restored Upper Midwest prairies and their presence in prairie renovations may be due to previous, intentional introductions.