LB 40-338 - Ecological Performance of Native Grasses Versus Traditional Sod Along Canal Banks in Southwest Florida

Thursday, August 10, 2023

5:00 PM – 6:30 PM PDT

Location: ESA Exhibit Hall

Presenting Author(s)

EH

Emily Hosea

Graduate Student
Florida Gulf Coast University, Florida, United States

Coauthor(s)

CW

Chad Washburn

Vice President of Conservation
Naples Botanical Garden, Florida, United States
BB

Brian Bovard

Professor
Florida Gulf Coast University, Florida, United States

Bahiagrass (Paspalum notatum) is regularly used in Southwest Florida (SWFL) landscaping due to its affordability and ability to withstand low water content. This species is commonly planted along canal banks and managed by frequent mowing. The regional water management district spends ~$1M annually on mowing maintenance. Grass clippings from mowing can enter adjacent and downstream aquatic systems, contributing to eutrophication. This study examines the use of 3 native grasses as low maintenance alternatives and aims to determine a viable species mixture to reduce mowing impacts and maintain soil stabilization and aesthetics. Our research site is located on a canal bank at Freedom Park in Naples, Florida. We used a randomized split-block design with four blocks measuring 1200 ft2. Each of the 24-meter-wide blocks was divided evenly into eight plots containing either a single species of Distichlis spicata, Paspalum vaginatum, or Sporobolus virginicus, or combinations of two or three species in equal proportions. Measurements of percent cover, height, and belowground biomass were collected every three months following planting. Optimal performance was characterized by 100% cover, with a mean height of ≤30 cm, and a well-developed root system. During the wet season, there was a significant interactive effect of species composition and elevation along the canal bank on mean maximum plant height (p=0.0007). Mean maximum height of P. vaginatum grown as a single species was tallest at low elevations (51.1 cm) and high elevations (47.6 cm) along the canal. The mean maximum height for the mixture of all three species was significantly higher at low elevations (43.3 cm) compared to high elevations (30.3 cm). Regardless of elevation, single species and combinations of D. spicata and S. virginicus demonstrated mean heights below the city ordinance of 30 cm maximum height (12.7 cm. – 26.2 cm). During the dry season, plants were significantly taller at lower elevations compared to high elevations along the canal (p < 0.05), and only P. vaginatum grown as a single species was significantly taller (38.4 cm) than the 30 cm maximum height requirement. All other species compositions were less than or equal to the 30 cm limit. Only control plots at high elevation had significantly higher belowground biomass 2 months after planting compared to all the other plant compositions (p=0.0004). This study suggests these native grasses produce viable root systems while maintaining average maximum heights lower than city ordinance requirements, and would reduce mowing maintenance costs and eutrophication impacts.