Light Response of Native and Introduced Miscanthus sinensis Seedlings

The Asian grass Miscanthus sinensis (Poaceae) is being considered for use as a bioenergy crop in the U.S. Corn Belt. Originally introduced to the United States for ornamental plantings, it escaped, forming invasive populations. The concern is that naturalized M. sinensis populations have evolved shade tolerance. We tested the hypothesis that seedlings from within the invasive U.S. range of M. sinensis would display traits associated with shade tolerance, namely increased area for light capture and phenotypic plasticity, compared with seedlings from the native Japanese populations. In a common garden experiment, seedlings of 80 half-sib maternal lines were grown from the native range (Japan) and 60 half-sib maternal lines from the invasive range (U.S.) under four light levels. Seedling leaf area, leaf size, growth, and biomass allocation were measured on the resulting seedlings after 12 wk. Seedlings from both regions responded strongly to the light gradient. High light conditions resulted in seedlings with greater leaf area, larger leaves, and a shift to greater belowground biomass investment, compared with shaded seedlings. Japanese seedlings produced more biomass and total leaf area than U.S. seedlings across all light levels. Generally, U.S. and Japanese seedlings allocated a similar amount of biomass to foliage and equal leaf area per leaf mass. Subtle differences in light response by region were observed for total leaf area, mass, growth, and leaf size. U.S. seedlings had slightly higher plasticity for total mass and leaf area but lower plasticity for measures of biomass allocation and leaf traits compared with Japanese seedlings. Our results do not provide general support for the hypothesis of increased M. sinensis shade tolerance within its introduced U.S. range compared with native Japanese populations.Nomenclature: Eulaliagrass; Miscanthus sinensis Anderss.Management Implications: Eulaliagrass (Miscanthus sinensis), an Asian species under consideration for biomass production in the Midwest, has escaped ornamental plantings in the United States to form naturalized populations. Evidence suggests that U.S. populations are able to tolerate relatively shady conditions, but it is unclear whether U.S. populations have greater shade tolerance than the relatively shade-intolerant populations within the species' native range in Asia. Increased shade tolerance could result in a broader range of invaded light environments within the introduced range of M. sinensis. However, results from our common garden experiment do not support the hypothesis of increased shade tolerance in introduced U.S. populations compared with seedlings from native Asian populations. Our results do demonstrate that for both U.S. and Japanese populations under low light conditions, M. sinensis seeds germinate and seedlings gain mass and leaf area; therefore, land managers should carefully monitor or eradicate M. sinensis within these habitats.