Fossil remains of the mycorrhizal fungal Glomus fasciculatum complex in postglacial lake sediments from Maine

Abstract

Specimens of the vesicular–arbuscular mycorrhizal fungal Glomus fasciculatum complex have been identified from lake sediment cores from Gould Pond (central Maine) and Upper South Branch Pond (north central Maine). The fungus became established with tundra vegetation on newly developing soils soon after the melting of Wisconsin ice. This is the first record of such an occurrence for North America. The earliest specimens from Gould Pond were deposited in sediment dated at about 13 000 years old and those at Upper South Branch Pond between about 12 500 and 11 000 years old. This is at least 1000 years prior to the arrival of trees in those areas. Sedimentologic and biologic evidence indicates soil instability and relatively high soil erosion rates from the watersheds during the late-glacial period. Thus erosion probably accounts for the abundance of Glomus in late-glacial sediments. The reduced abundance of the fungus in Holocene sediments is attributed to a decrease in the rate of soil erosion after the establishment of trees.