Miscanthus sinensis and Panicum virgatum Competition Study

Many different vegetatively propagated cultivars of Miscanthus sinensis Anderss. are popular ornamental grasses sold at garden centers and nurseries. Large stands of the “wild type” or species (not ornamental cultivars) of this grass have self-seeded near Asheville, N.C.; Valley Forge, Pa.; and Washington, D.C. In order to document the competitive ability of this self-seeded naturalized species, a greenhouse competition study was conducted with Panicum virgatum L. `Forestburg' (P), switchgrass, and several non-native, naturalized biotypes of Miscanthus sinensis (M) grown from seed collected from the above locations. Seedlings were transplanted into #1 (2.88 L) containers in nine different planting arrangements: 2M; 4M; 8M; 2M2P; 4M4P; 8M8P; 2P; 4P; 8P, and grown for 15 weeks. Growth measurements were taken during the 15 weeks. At harvest, shoot and root dry weights were calculated. Panicum had significantly larger root (0.50 g vs. 6.00 g) and shoot (6.96 g vs. 2.3 g) biomass, respectively, than Miscanthus . Intraspecific competition in monocultures was significantly higher for Panicum than Miscanthus. Panicum showed higher competitive ability than all Miscanthus biotypes, with one exception: root dry weights of one Pennsylvania biotype. Panicum increased in dry weight at the expense of Miscanthus. Panicum dominated Miscanthus during the 15 weeks and, in this study, proved to be a better competitor than Miscanthus. Miscanthus and Panicum did not fully share the common limiting resources and they showed partial resource complementarity. Miscanthus biotype variation was evident; the highest dry weights were from a Pennsylvania biotype and the smallest weights were from a Washington, D.C., biotype.