Road Crossings Increase Methane Emissions From Adjacent Peatland

Abstract

Abstract We conducted a multi‐year study in two boreal peatlands to determine the impacts of resource access roads on methane (CH 4 ) emission from adjacent peatland. Data were collected from transects aligned perpendicular to, and on both sides of two roads, one cutting through a bog and one cutting through a fen and from reference areas at each peatland. During the growing seasons of 2016 and 2017, we measured CH 4 flux, water table, and peat temperature every second week. At the bog, the road associated impacts (changes to water table, peat temperature, and vegetation cover) were visible up to 20 m on both sides of the road (disturbed areas) with CH 4 emission from disturbed areas being significantly higher compared to the reference areas in both years. There were no significant differences in CH 4 emissions from disturbed areas compared to reference areas at the fen due to the limited hydrologic impact of the road crossing at this site. Bog plots located upstream of the road on transects located at >20 m from culverts and closer to the road emitted significantly more CH 4 (124.6‐mg CH 4 ·m −2 ·day −1 ) than other disturbed (10.2 mg CH 4 ·m −2 ·day ‐1 ) and reference areas (0.7‐mg CH 4 ·m −2 ·day −1 ) due to shallower water table and warmer peat temperature. The road induced CH 4 emissions (90.8 and 212.2 kg CH 4 /year for each kilometer of road, in 2016 and 2017, respectively) indicated that road construction across peatlands enhances CH 4 emissions from these ecosystems, creating an additional source of anthropogenic greenhouse gas.