Productivity and profitability of harvesting overgrown roadside verges – a Swedish case study

Despite the large biomass potential, current management practices for roadside verges (ditch backslopes,foreslopes and bottoms, possible parking lots and other lateral land) consist of regularly cutting the vegetation manually with motorized brush saws or flail mowers and leaving it to rot in situ. Regular vegetation clearing is crucial for safety reasons and to maintain road functionality. This study considered the cost-efficiency of a mechanized harvesting system, using a harvester and a forwarder (as an alternative to current clearing practices), to maintain the verges of a forest road in northern Sweden. Cutting a 2.5-m wide swath on each verge removed between 32 and 112 dry t ha−1 (16–56 dry t km−1 of road) of biomass. Analyses showed that the use of forest machinery to cut and extract biomass from roadside verges can be cost-competitive compared with motor-manual clearing when the average tree height is above 7 m (~26-year-old trees), and profitable for average heights above 8 m (~29-year-old trees). As the overgrown biomass has to be cleared anyway, a mechanized harvest could partially or fully offset maintenance costs. When setting cutting intervals, a trade-off needs to be made between larger biomass production and maintaining a clear and safe road. Future research needs to investigate how size, density of vegetation and width of the cleared swath affects the long-term quality and safety of roads.