Assessing the Invasive Potential of Miscanthus Biofeedstocks in Illinois

Authors: Matlaga, David; Davis, Adam

Submitted to: Weeds without Borders Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2010
Publication Date: 6/10/2010
Citation: Matlaga, D.P., Davis, A.S. 2010. Assessing the Invasive Potential of Miscanthus Biofeedstocks in Illinois. Weeds Without Borders Proceedings. p. 70-77.

Interpretive Summary: The global push to cultivate biofuel crops has increased incentives to move exotic plants over large spatial scales, creating concern that exotics will escape cultivation and become noxious weeds. Candidate biofuel crops share key characteristics with weeds (i.e. rapid growth, vegetative spread) and many are known to escape plantings and even become invasive. We are using several complementary approaches to experimentally estimate components of the invasion process for two candidate biofuel feedstocks, Miscanthus x. giganteus and Miscanthus sinensis, in Illinois. To understand both the spatial scale at which escape may occur from production fields, and the speed at which established populations may spread, we estimated dispersal distances in the field for wind-borne Miscanthus propagules. Seeds were captured on sticky cards at varying distances, up to 400m, from a source of 600 experimentally placed Miscanthus seedheads. Compared to M. sinensis, the distribution of dispersal distances for M. giganteus caryopses was much farther, reaching up to 400m. Dispersal distributions were in agreement with seed weights, with M. sinensis seeds weighing over twice as much as those of M. x. giganteus. Future work includes using estimates of dispersal distances and survival to be used in computer models of Miscanthus spread rates for established populations.

Technical Abstract: Rapid expansion of the plant bioeconomy has increased incentives to distribute exotic plants over large spatial scales, creating concern that exotics will escape cultivation and become noxious weeds. This concern is particularly relevant in the global push to cultivate biofuel crops. Candidate biofeedstocks share key traits with weeds (i.e. rapid growth, clonal spread) and many are known to become naturalized and even invasive. We are using several complementary approaches to experimentally estimate components of the invasion process for two candidate feedstocks, Miscanthus x. giganteus and Miscanthus sinensis, in Illinois. To understand both the spatial scale at which escape may occur from production fields, and the speed at which established populations may spread, we empirically estimated dispersal kernels for wind-borne Miscanthus propagules. Caryopses were captured on sticky cards at varying distances, up to 400m, from a source of 600 experimentally placed Miscanthus spikelets. Compared to M. sinensis, the negative-exponential distribution of dispersal distances for M. giganteus caryopses was much longer-tailed, reaching up to 400m. Dispersal distributions were in agreement with caryopsis weights, with M. sinensis caryopses weighing over twice as much as those of M. x. giganteus. Future work includes using empirical estimates of dispersal and demography to parameterize integrodifference equation models of Miscanthus spread rates for established populations.