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Evaluating Management Options to Increase Roadside Carbon Sequestration II

Project #: 4W6637
Start Date: 04/06/2017
End Date: 12/31/2017
Status: Completed

As described in the final report (which summarizes results from Phase 1 and Phase 2), the research team estimated the amount of carbon sequestered along Montana Department of Transportation (MDT) roads and tested 3 different highway right-of-way (ROW) management techniques to increase carbon stocks. Using Geographic Information System techniques, the total ROW acreage owned by MDT was found to sequester 75,292 metric tons of carbon per year and to consist mostly of grasslands (70%). From 2016-2018, researchers tested 3 ROW management techniques to increase carbon stocks- increase mowing height, plant woody shrubs, or add legumes to reclamation seed mixes of disturbed soils – at 3 sites (Three Forks [3F], Bear Canyon [BC], and Bozeman Pass [BP]) along Interstate 90 in southwestern Montana. Soil samples generally averaged 0.75–1.5% soil organic carbon (SOC) at the 3F site, 2.5–4% SOC at the BC site, and 1.5–2.5% SOC at the BP site. Average SOC levels were always lower in 2018 than in 2016. Soil respiration rates were generally highest in June or July at the BC site, averaging ~4 μmol CO2 m-2 second-1. Soil respiration rates were lower at the BC site in November 2016, at the BP site in June 2018, and at the 3F site in July 2018 (all ~2–3 μmol CO2 m-2 s-1). Aboveground biomass carbon estimates generally mirrored belowground SOC estimates. Taken together, the findings suggest that of the three treatments implemented (raised mowing height, shrub planting, and disturbance), minimizing disturbance to soils likely makes the greatest contribution to the medium- and long-term carbon-storage potential of these roadside soils.


Interest has recently been increasing in the potential for roadside vegetation and soils to capture and store carbon in order to reduce the atmospheric concentration of carbon dioxide (CO2). Previous research demonstrates the great potential for easily accessible roadsides to be more focused on active carbon management. Unfortunately, no management guides have quantified methods for maximizing carbon sequestration rates in roadside soils and vegetation while simultaneously meeting safety guidelines.

The Center for Environmentally Sustainable Transportation in Cold Climates (CESTiCC) is conducting a study to quantify carbon management outcomes for more northern, colder ecosystems. Components include:

  • estimating how much roadside acreage exists and how much carbon is currently being captured and stored along Montana DOT’s roadsides.
  • calculating how much of this acreage is available for active carbon management.
  • constructing experimental plots to determine if changing three different management practices of roadside vegetation and soils can increase existing levels of carbon capture and storage.

This follow-up project will extend the field work for an additional growing season.


The objective of this project is to extend an existing research effort to determine if changing three different management practices of roadside vegetation and soils can increase existing levels of carbon capture and storage.