Soil properties limiting vegetation establishment along roadsides

Roadside vegetation provides a multitude of ecosystem services including pollutant remediation, runoff reduction, wildlife habitat, and aesthetic scenery. Establishment of permanent vegetation along paved roads after construction can be challenging, particularly within 1 m of the pavement. Adverse soil conditions could be one of the leading factors limiting roadside vegetation growth. In this study, we assessed soil physical and chemical properties along a transect perpendicular to the road at six micro-topographic positions (road edge, shoulder, side slope, ditch, backslope, and field edge) along two highway segments near Beaver Crossing and Sargent, NE, USA. At the Beaver Crossing site, Na concentration was 81 times, exchangeable Na 66 times, and cone index (compaction parameter) 6 times higher at the road edge position (closest to the paved road and with sparse vegetation) compared to positions with abundant vegetation (ditch or field edge). At the Sargent site, Na concentration was 111 times, exchangeable Na 213 times, and cone index up to 2 times higher at the road edge compared to ditch or field edge positions. Likewise, electrical conductivity (EC) was higher while macroaggregation and water infiltration were lower at the road edge than ditch or field edge positions. Soil properties improved with increasing distance from the road. Exchangeable Na percentage and cone index at the road edge exceeded threshold levels for growth of sensitive plants. Thus, high Na concentration and increased compaction at the road edge appear to be the leading soil properties limiting vegetation establishment along Nebraska highways. This article is protected by copyright. All rights reserved.