Saltmarsh archives of vegetation and land use change from Big River Marsh, SW Newfoundland, Canada

Abstract

Pollen and plant macrofossils are often well-preserved in coastal sediments, providing a palaeoenvironmental record of sea-level and landscape change. In this study, we examine the pollen and plant macrofossil assemblages of a well-dated saltmarsh sediment core from southwest Newfoundland, Canada, to establish recent coastal vegetation and land use change, to increase the knowledge of anthropogenic activities in the area and develop pollen chronozones for reconstructing marsh accumulation rates and to examine the representation of plant macrofossil remains in the wetland pollen profile. Grouping the pollen record into upland and wetland assemblages allows local events related to hydrological change to be separated from landscape-scale changes. The wetland pollen and plant macrofossil records indicate a general acceleration in sea-level rise ca. ad 1700. The sedge pollen and plant macrofossil records attest to multiple phases of rhizome encroachment during inferred periods of marine regression. Two chronozones are identified from the upland pollen profile; the first associated with the settlement of St. George’s Bay ca. ad 1800, signalled by increases in Plantago lanceolata and Ambrosia pollen; the second with the permanent settlement of the Port au Port peninsula ca. ad 1850, indicated by increased P. lanceolata and Rumex pollen. Comparison of the plant macrofossil and wetland pollen profiles highlights the underrepresentation of grass pollen preserved in the saltmarsh sediments and a need for further analysis of the zonation, pollen dispersal and macrofossil representation of sedge species in saltmarshes.