Ecological refugia as a conservation practice in agricultural systems

Hannah Duff, Land Resources and Environmental Science, Montana State University, Bozeman, MT and Bruce Maxwell, Land Resources and Environmental Sciences, Montana State University, Bozeman, MT

Background/Question/Methods
Today we are faced with a huge struggle between food production and ecological conservation. While agriculture is already acknowledged as a major driver of global biodiversity loss, we will need to produce 60-110% more food to feed our planet by 2050. New agroecological solutions are needed that benefit natural systems and production systems. Transforming low-producing areas on farm fields into ecological refugia may provide small-scale habitat and ecosystem services in fragmented agricultural landscapes. We collaborated with three precision agriculture producers in Montana to see if on-farm ecological refugia support biodiversity, enhance beneficial ecosystem services and increase food production. Vegetation surveys were conducted on each farm in a radial web design of six transects that started in the refugia center and ran 200 meters into the crop field. On each farm, a sampling web was replicated in a neighboring field that had no refugia. The sampling webs were used to sweep net insects in 20-meter intervals. Small mammal seed predation was tested using 30 seed traps per web where each trap contained two weed and two crop species.
Results/Conclusions
Native plant species richness was concentrated at refugia centers and declined with distance into the crop field (p-value < 0.01). According to a Bayesian Kriging interpolation, just as native plant species richness decreased with distance from refugia, we would expect beneficial ecosystem services such as pollination or pest-predator habitat provision to decline with distance into the crop field. In contrast, non-native species richness was highest in the crop field and lower in refugia, indicating that ecological refugia are not sources of undesirable weedy species. Insect diversity declined significantly with distance from refugia (p-value < 0.0001). Fields with refugia had higher abundance for insects associated with beneficial ecosystem services such as nutrient cycling, insect pest predation and weed control (p-value < 0.05). Fields without refugia had significantly higher abundance of insects from pest functional groups associated with yield reduction (p-value < 0.05). Seed trap data indicated that small mammal crop seed predation was concentrated around refugia. This suggests that seed predators may provide a beneficial service of weed suppression by eating volunteer seeds or a disservice of reducing crop yield by eating newly planted seeds. Precision agriculture yield maps showed a significant decline in crop yield with distance from refugia (p-value < 0.0001). Future research will assess the feasibility of implementing ecological refugia as a conservation practice in agricultural landscapes.