Can Mulch and Fertilizer Alone Rehabilitate Surface-disturbed Subarctic Peatlands?

Abstract

Subarctic peatlands are increasingly faced with disturbances from resource extraction industries. Their rehabilitation is being required through government regulation, and backed by financial guarantees. A three-year field experiment was conducted to test a modification of existing peatland rehabilitation protocols on winter road clearances in subarctic peatlands of the Hudson Bay Lowland. The experiment was conducted on severely disturbed sections of winter roads with extensive cut hummocks. Sphagnum fragments were not spread on bare peat surfaces, contrary to existing protocols, because of the close proximity to propagules in vast and adjacent, undisturbed peatlands. Factorial combinations of microclimate amelioration (straw mulch) and phosphorus fertilization were applied, as in existing protocols. Rock phosphate fertilization and straw mulch did not increase the recolonization of Sphagnum nor of other bryophytes, lichens or vascular plants. After three years, Sphagnum remained almost absent and bare peat was colonized mostly by lichens and bryophytes typical of disturbed peat surfaces. The spreading of fragments on top of severely disturbed surface peats appears to be required in order to rehabilitate peatlands, even when extensive undisturbed peatlands are found nearby.