Restoration and ecology of Arundinaria gigantea: Field and laboratory studies

The once dominant Arundinaria gigantea (Walt.) Muhl. canebrake ecosystem has been reduced to fragmented populations, trapped between increasing anthropogenic development and closed canopy forests. This decline in the A. gigantea population has resulted in a critically endangered ecosystem, impacting many species and making reestablishment of canebrakes necessary for maintaining and enhancing biodiversity in the southeastern United States. To facilitate restoration of canebrakes, we compared historical and present distributions, sampled remnant brake environments, and tested effects of environmental factors (e.g., nutrients and light) on A. gigantea growth. For the latter, thinning sites were established in existing cane populations and forest canopy reduced 60%, a field experiment was set up to test effects of competition and nutrients (P, N, P+N) on rhizome transplants, and a laboratory experiment was conducted to test light (partial shading and full light) and nitrogen (0, 0.5, 1.0, 25, and 100 g/L) effects on seedling growth. Additionally, a light response curve was conducted to examine plant light usage (A. gigantea remained photosynthetically active throughout the winter). Results indicated A. gigantea growth was enhanced with increased light levels and nutrients, both N and P. Of particular interest was increased root and rhizome biomass, which could be critical for improving establishment and survival of plants to a restoration site. Historically, canebrakes were more widespread, less fragmented, and occurred in a wider variety of floodplain environments than their present distribution suggests. Reduction of overstory canopy and transplants into old fields were experimentally-supported management strategies for increasing existing populations.