Modification by an invasive ecosystem engineer shifts a wet prairie to a monotypic stand

At the landscape scale, ecosystem engineers are expected to increase species diversity; however, diversity could decline if the ecosystem engineer is over-abundant. Thus, invasive ecosystem engineers are expected to have strong impacts, due to their high abundances and novel disturbances. An invasive ecosystem engineer, the feral swine (Sus scrofa), is a species that creates intense soil disturbances, altering soil and plant communities. In this study, we examine the effects of this invasive ecosystem engineer on experimental plant plots that had been protected for over a decade. Feral swine avoided recently burned plots and preferred plots with N addition. Rooted plots shifted from a bunchgrass dominated wet prairie to a monotypic stand of the native, Lachnanthes caroliana. Feral swine were also attracted to plots with existing patches of L. caroliana suggesting a potential positive feedback between swine activity and L. caroliana patch expansion that could result in an alternative state.