Photosynthetic Characteristics of the C₄Invasive Exotic Grass Miscanthus sinensis Andersson Growing Along Gradients of Light Intensity in the Southeastern United States

Abstract

Miscanthus sinensis, a C4 grass, is an emerging invasive species in open and edge habitats throughout the eastern United States. To assess its ability to invade forest understories, we examined photosynthetic responses of Miscanthus sinensis grown under natural light gradients (5% to 100% full sunlight). Although there was a slight reduction in reproductive output under lower light, Miscanthus sinensis was able to maintain high rates of photosynthesis and positive carbon gain along the entire light gradient. Positive carbon gain at low light was likely due to an increased quantum yield. Photosynthetic induction for all plants was rapid, while stomatal opening during induction was slower. Rates of induction loss were slower than induction gain, and were slower than another major C4 invasive exotic grass, Microstegium vimineum that is shade tolerant. During transient high light events, the combination of rapid induction, maintenance of induction state between sunflecks, and high photosynthetic rates, may allow for greater carbon gain than native understory plants. Miscanthus sinensis possesses some characteristics that allow it to persist in forest understories and to rapidly utilize increases in light availability, rendering it a potentially important invader of southeastern United States forest understories.