Evaluation of intercropped switchgrass establishment under a range of experimental site preparation treatments in a forested setting on the Lower Coastal Plain of NorthCarolina, U.S.A

There is growing interest in using switchgrass (Panicum virgatum L.) as a biofuel crop and for its potential to sequester carbon. However, there are limited data on the establishment success of this species when grown as a forest intercrop in coastal plain settings of the U.S. Southeast. Therefore, we studied establishment success of switchgrass within experimental intercropped plots and in pure switchgrass plots in an intensively managed loblolly pine (Pinus taeda) plantation in eastern North Carolina. Pine trees were planted in the winter of 2008, and switchgrass was planted in the summer of 2009. Establishment success of switchgrass was measured over the growing season from May to October 2010, and quantified in terms of percent cover, height (cm), tiller density (number of tillers m ), leaf area index and biomass (Mg ha ). At the end of the growing season, pure switchgrass plots were taller than the intercropped treatments (114 2 cm versus 98 1 cm, respectively), but no significant treatment effects were evident in the other variables measured. Switchgrass biomass across all treatments increased from 2.65 0.81 Mg ha 1 in 2009 to 4.14 0.45 Mg ha 1 in 2010. There was no significant effect of distance from the pine row on any switchgrass growth parameters. However, we anticipate a shading effect over time that may limit switchgrass growth as the pines approach stand closure. a 2012 Elsevier Ltd. All rights reserved.