Gatekeepers of transformation: private landowners evaluate invasives based on impacts to ecosystem services.
Biological invasions are not new, yet the anthropogenic drivers of global change have produced unprecedented ecological novelty through the expansion of invasive species. Private landowners play an important role in determining the trajectory of ecological transformations driven by invasives. Using the northern Great Plains of the USA as a case study, we examined private landowners' role as gatekeepers for an invasive species. We employed a factorial vignette survey experiment to understand how the impacts of an unnamed invasive grass modeled on Kentucky bluegrass (Poa pratensis L.) were related to landowners' acceptance of the species. We also explored the relationship between landowners' acceptance of the invasive grass and their management intention to reduce/control the species. Each landowner evaluated multiple vignettes that randomly varied based on how a novel grass species expanding in rangelands would affect provisioning services (season of forage availability, forage quality, forage quantity), regulating services (floral resources for pollinators, water infiltration and availability), and supporting services (grassland bird diversity, grass diversity). Acceptability was strongly associated with landowners' management intentions, and the status of all seven services was related to acceptability. Reductions to any ecosystem service reduced the acceptability of the invasive grass species; however, only increases in forage quality, forage quantity, and water regulation were related to increased acceptability of the invasive. Scenario modeling shows that landowners displayed greater sensitivity to losses in a suite of ecosystem services than to equivalent gains. Scenarios specific to ecosystem service trade-offs and Kentucky bluegrass invasion indicate that ecological losses may need to be severe before individual landowners change their management practices to reduce/control the species. Given the high thresholds for individual behavioral change, engaging private landowners in collaborative management efforts, whether to control an invasive grass or guide management toward co-existence, may be helpful to conserve desired biodiversity and the flow of ecosystem services from northern Great Plains grasslands.