Within the chosen timeframe of this project ranging from the onset of Neolithic (in Sweden some 6000 years ago), it is fairly well known that major changes in land-use have occurred. Deliberate removal of forests, achieved by cutting or fire, has been one of the most significant ways in which humans have modified the environment. Less well known are the environmental effects of historical changes in land-use, especially when it comes to the ecosystem response in coastal and open parts of the Baltic Sea.

Aim and research question

The overarching aim of this proposed project is to disentangle the long-term role of human impact (through the periods of expansion, colonization, deforestation versus the periods of recession, retreat, reforestation) and natural driven processes (e.g. earlier climate change and isostatic uplift) to determine the mutual significance of the multiple stressors resulting in events of hypoxia in the Baltic Sea. The outlined aim will be addressed by focusing on the following overarching research questions:

What changes in the landscape are recorded since Neolithic in the selected studyarea and how have these affected the humans living along the seaside?
What influence have humans had on the environment in the area through time and how hasthis impact been registered?
To what extent have human onshore activities contributed to alteration of the BalticSea environmental status, locally as well as regionally?

Case study

Our study is transdisciplinary and has a unique combination of expertise in both Earth Scienceand
Archaeological Landscape analyze working together with bottom survey experts from a private company. Methodologically we will focus on a couple of specific small-scale sites chosen carefully from a combination of these perspectives. The practical fieldwork and the sampling strategy will be a combination of our joint experience from paleoecology and maritime archaeology.

The geographical focus is put on the Baltic Sea coastal zone to investigate how the ecosystem has responded to changes in land-use, as well as the other way around; how humans adapted to changes in the configuration of the landscape (e.g. shifting shorelines). Our intention is to apply an in-depth case study on carefully selected Baltic coastal sites, as well as isolated lake sites at different altitudes. Selected area for the case study is Gamlebyviken area, situated in the province of Småland, a rural coastal area exceptionally rich regarding prehistoric remains from different periods.

Methods

Archaeological:

MARIS at Södertörn University has since 2008 had a long-term successful
cooperation with the survey company MMT regarding underwater
investigations and surveys. A special challenge in this case is how to
find old archeological finds and cultural layers deep down in soft
sediments under water. In this project, we therefor aim to combine
geological and archeological knowledge regarding topographic and
sediment analyzes. Based on that, we will use traditional piston and
gravity coresampling as reference for new investigations with low frequency sonars and maritime archeological test excavations.

Land-use changes:

In this study, we will use a combination of paleoecological methods in combination with historical documents and archaeological finds to obtain a complete picture of the intermittently changing landscape and distinguish periods with human expansion and contraction. The paleoecological approach include pollen, charcoal and grain-size stratigraphies on sediment cores from carefully selected lake-sites. To be able to infer land-use changes we will apply the model REVEALS.

Changes in the coastal zone:

To infer anthropogenic impact in the Baltic Sea coastal zone we intend to use both paleoecological (diatom stratigraphies and diatom-based transfer functions) and geochemical methods (TOC, C/N-ratio, stable N and C isotopes) on sediment cores.

Shore displacement:

A shore displacement curve will be constructed by studying when lake basins situated at various altitudes were isolated from the Baltic Sea basin. The isolation is visible both as a lithological transition (increased TOC-content) and as shifts in diatom stratigraphy (from brackish to freshwater taxa).

All sediment cores will be dated by 14C (AMS) and age-depth models constructed in order to establish reliable chronologies.