Vegetative dispersal of perennial bioenergy crops as a potential invasion route

Authors: West, Natalie; MATLAGA, DAVID - Susquehanna University; Davis, Adam

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2014
Publication Date: 10/2/2015
Citation: West, N.M., Matlaga, D., Davis, A.S. 2015. Vegetative dispersal of perennial bioenergy crops as a potential invasion route. Invasive Plant Science and Management. 7:517-525.

Interpretive Summary: Many plant invasions in the U.S. have had their origins in crop introductions gone awry. The current push to generate more energy from crop plant biomass offers a novel opportunity to reduce invasion potential of introduced crops by combining predictions from invasion ecology with insights from agronomy to create guidelines for safe management of bioenergy crops. The invasion potential of Miscanthus x giganteus, a widely planted biofeedstock, has been downplayed or ignored in most discussions of bioenergy crop development. As a seed infertile species, it lacks an obvious mechanism of long distance dispersal, a key contributor to invasion rate, and thus has been considered a low risk for cultivation escape. Assessments of this species assume proper management through time, as well as the rarity of events such as scouring and flooding that would facilitate dispersal of vegetative rhizome fragments. Combining data from small scale rhizome fragmentation and movement experiments, and estimates from the literature, we parameterized an individual based model to examine the rate of M. x giganteus spread given two dispersal scenarios. We further evaluated model behavior in response to different buffer widths and monitoring intensities, two key strategies advised for containing biofuel crops. We found that estimates of the vegetative expansion rate alone were sufficient to allow the crop to outgrow setbacks of 3 m or less within 11 to 15 years with low monitoring intensities. Further, models that included the possibility of rhizome dispersal from fields and scouring at field edges support the possibility of long distance dispersal and establishment if management intensities are too low. Our study highlights the importance of considering minimum enforced management guidelines for growers to maintain the ecological integrity of the agricultural landscape.

Technical Abstract: Miscanthus x giganteus, a widely planted biofeedstock, has been largely ignored in discussions of potential invasiveness of biofuel crops. As a seed infertile species, it lacks an obvious mechanism of long distance dispersal, a key contributor to invasion rate, and thus has been considered a low risk for cultivation escape. However, cultivation shelters plants from demographic stochasticity, increasing propagule pressure, and potentially reducing limitations that prevent low risk species from taking advantage of rare dispersal events. Assessments of this species assume proper management through time, as well as the rarity of events such as scouring and flooding that would facilitate dispersal of vegetative rhizome fragments. Combining data from small scale rhizome fragmentation and movement experiments, and estimates from the literature, we parameterized an individual based model to examine the rate of M. x giganteus spread given two dispersal scenarios. We further evaluated the sensitivity of our estimates in response to different buffer widths and monitoring intensities, two key strategies advised for containing biofuel crops. We found that estimates of the clonal expansion rate alone were sufficient to allow the crop to outgrow setbacks of 3 m or less within 11 to 15 years with low monitoring intensities. Further, models that included the possibility of rhizome dispersal from fields and scouring at field edges support the possibility of long distance dispersal and establishment if management intensities are too low. Our study highlights the importance of considering minimum enforced management guidelines for growers to maintain the ecological integrity of the agricultural landscape.