European Impacts on Coastal Eastern Tasmania: Insight from a High-Resolution Palynological Analysis of a Salt-Marsh Core

Patrick T Moss,W Roland Gehrels,S Louise Callard

doi:10.3389/fevo.2016.00105

Abstract

A high-resolution pollen and micro-charcoal (>5 μm) record has been produced from a short sediment (50 cm) core recovered from a salt marsh in the Little Swanport Estuary, eastern Tasmania. This record suggests that there are four phases associated with the European settlement of the region. An initial phase from around 1830 to 1858 AD, which is similar to the previous Aboriginal period; a relatively low impact transitional phase from 1859 to 1898 AD; a rapid and marked deforestation period from 1899 to 1932 AD; and establishment of the contemporary landscape, with reforestation occurring, but with marked differences in species composition (i.e. greater representation of exotic taxa and altered understorey composition) from 1933 to 2006 AD. Key similarities are seen across Australia with the European settlement phase (i.e. addition of exotic taxa, deforestation and/or changes in vegetation composition, alterations in fire regimes and increased sedimentation rates), but high-resolution analysis suggests that these impacts may manifest in different ways depending on the local environmental setting and/or historical context of the settlement location. Furthermore, Amaranthaceae pollen representation appears to be impacted by changes in sea level. However, other factors such as human modifications, particularly grazing, and climate variability may play additional roles and further research is required to disentangle the relative effects of these factors.

Highlights

European settlement of Australia, as well as other New World landscapes, has profoundly altered human-environment relationships (Roberts et al, 2001)
Those records that do exist suggest that there is a great deal of regional variation in the timing and nature of ecosystem response to European settlement, with some alterations linked to obvious European impacts, such as land clearance (e.g., Moss et al, 2007), while other ecological alterations are linked to much more subtle changes in land management, the imposition of new fire regimes (e.g., Fletcher et al, 2014)
The high-resolution pollen and micro-charcoal record derived from the Little Swanport salt marsh in eastern Tasmania provides detailed evidence of the profound impact that European settlement had on the coastal landscape

Summary

Introduction

European settlement of Australia, as well as other New World landscapes, has profoundly altered human-environment relationships (Roberts et al, 2001). European Impacts focus on Aboriginal human-environment relationships (e.g., Colhoun and Shimeld, 2012; Ulm, 2013; Fletcher et al, 2014, 2015; Rees et al, 2015; Mackenzie and Moss, in press for recent publications from Tasmania) Those records that do exist suggest that there is a great deal of regional variation in the timing and nature of ecosystem response to European settlement, with some alterations linked to obvious European impacts, such as land clearance (e.g., Moss et al, 2007), while other ecological alterations are linked to much more subtle changes in land management, the imposition of new fire regimes (e.g., Fletcher et al, 2014). This study will provide insight into the scale of European impacts for coastal eastern Tasmania through the high-resolution analysis of a 180-year record from a salt marsh located in the estuary of the Little Swanport River

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