Successional Establishment, Mowing Response, and Erosion Control Characteristics of Roadside Vegetation in Texas

The purpose of this project was to investigate whether the Texas Department of Transportation's (TxDOT’s) standard seed mix needs modifications to better address the issue of invasive species while the primary goal of erosion control can still be well achieved. The research objectives were to investigate: (1) the successional process of roadside grasses using TxDOT’s seed mix and seeding procedure on field laboratory test plots and actual roadsides, (2) erosion control properties of vegetation on 12 new plots seeded with TxDOT’s standard seed mix and 10 existing plots originally seeded with a non-TxDOT seed mix, and (3) the impacts of mowing on establishing and established grass communities. To achieve these objectives, the researchers conducted field laboratory experiments and actual highway roadside surveys. The results indicate that roadsides as maintained and mowed environments cannot be easily adapted by tall grass species (native or introduced). Short, sod-forming grasses, however, could grow better on roadsides. It was found that grass species in TxDOT's standard seed mixes did not show invasiveness on investigated laboratory plots and actual roadsides. The researchers also found little connection between original seeded grass species and observed grass species several years after seeding. This implies that volunteer species either from adjacent lands or from seed banks in the soil tend to dominate roadsides in the long term. All field laboratory plots controlled erosion very well. Yielded sediments were much below the TxDOT’s minimum performance standards. Little literature was found on cost and benefit analysis about roadside management as a result of a lack of consistent cost database data held by state DOTs, which suggests future research on creating a database for comparing cost-benefit between the uses of natives and introduced grasses.