Abstract
Bahiagrass (Paspalum notatum) is a commonly utilized commercial groundcover grass in Southwest Florida (SWFL) due to its ready availability, and pest and drought resistance. However, the extensive mowing required for its maintenance poses a significant cost to local natural resource managers with approximately one million dollars spent annually in SWFL. Moreover, the grass clippings from mowing can contribute to the eutrophication of adjacent aquatic systems. This study examines the alternative use of three native, potentially low-maintenance, SWFL grass species, which could also provide soil stabilization and aesthetic appeal, in lieu of P. notatum.A randomized split block design experiment was conducted on the canal banks within Freedom Park in Naples, FL. Each block was divided into eight plots, with seven plots featuring either a single species—Distichlis spicata, Paspalum vaginatum, or Sporobolus virginicus—or one of all possible combinations of the three species in equal proportions. The species mixture treatments included every combination of the three species, with an equal number of individuals per species evenly distributed within each plot. For example, in Block 1, the treatments were: D. spicata, P. vaginatum, S. virginicus, D. spicata & P. vaginatum, D. spicata & S. virginicus, P. vaginatum & S. virginicus, D. spicata, P. vaginatum & S. virginicus, and the control plot (100% bahiagrass). The eighth plot served as a control and contained only bahiagrass. Measurements of percent cover, mean maximum height, and belowground biomass were taken quarterly following planting, with optimal performance defined as target species percent over greater than or equal to the control (bahiagrass), a mean maximum height of ≤ 30 cm, and a comparable root mass to the control.
Results from the final mean maximum plant height indicated single species and combinations of D. spicata and S. virginicus demonstrated mean maximum heights below the benchmark of 30 cm. At the end of the experiment, S. virginicus and a combination of all three native species had a significantly higher coverage of target species than the control (p< 0.0032). No significant difference in underground biomass between native species and the control were observed in this experiment (p= 0.89).
This study suggests native grass species from SWFL can establish a significant target species ground cover, underground biomass comparable to the control all while staying below a 30 cm benchmark height and offering potential reductions in mowing maintenance and eutrophication impacts. Results from this research suggest alternative management that is both more nature-based and more economical. In conclusion, this study demonstrates the potential of native grass species to serve as alternatives to bahiagrass for groundcover in SWFL. Native species like Distichlis spicata and Sporobolus virginicus exhibited optimal performance in terms of ground cover and height while maintaining comparable root biomass to bahiagrass. Moreover, these native species offer the additional benefits of reduced mowing maintenance which could reduce clipping inputs into waterways and potentially decreased eutrophication impacts, making them promising choices for landscaping and soil stabilization efforts in the region.