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

Katherine A Selby,Alexander J Wright,Orson Van De Plassche,Helen M Roe,Sally R Derrett

doi:10.1007/s00334-021-00845-y

Katherine A Selby, Alexander J Wright + Show 3 more

Open Access

https://doi.org/10.1007/s00334-021-00845-y

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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.

Highlights

Saltmarshes as archives of land‐use changeSaltmarshes are highly dynamic environments that possess an intrinsic vertical and horizontal relationship with sea level, producing near-continuous records of sediment accumulation over time (Barlow et al 2013; Brain et al 2015; Wright et al 2017)
The second chronozone is represented by a second peak in P. lanceolata and a small increase in Rumex pollen levels following increased seasonal and permanent settlement of the Port au Port peninsula in the mid 1800s
Saltmarsh sediments are often a successful source of well-preserved pollen and plant macrofossil remains from the late Holocene

Summary

Introduction

Saltmarshes are highly dynamic environments that possess an intrinsic vertical and horizontal relationship with sea level, producing near-continuous records of sediment accumulation over time (Barlow et al 2013; Brain et al 2015; Wright et al 2017). As such, they are commonly used for Communicated by K. Saltmarshes accumulate sediment and plant remains to maintain their position in the tidal frame in response to relative sea-level (RSL) rise (Kemp et al 2018). Relative sea-level reconstructions based on foraminiferal analyses from saltmarsh sediment cores undertaken by Wright et al (2011) and Kemp et al (2017) demonstrate the potential decimetre-scale

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