Agricultural activity and its impact on terrestrial and marine ecosystems in the Baltic Sea region during the past 6000 years

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The proposed project aims at the assessment of agricultural activity during the past 6000 years and of coeval changes in climate and in terrestrial and marine ecosystems in the Baltic Sea region. This shall be achieved by the examination of multi-decadal palynological records from four IODP-Expedition-347 sites. The main hypotheses of the projects are that a) agricultural activity started earlier in coastal areas of the Baltic region and spread from the South to the North, b) agricultural activity resulted in related environmental changes such as deforestation, c) climate parameters such as precipitation influenced the intensity of cereal farming, and d) agricultural activity had an impact on marine ecosystems which can be identified in assemblages of aquatic palynomorphs and other microfossils. The four selected sites are situated in the south-western (Site M0059), the central (Site M0063), and the north-western Baltic Sea (Sites M0061/M0062). Agricultural activity shall be recognized via occurrences of pollen grains of cultivated plants, particularly cereals such as rye (Secale) or wheat (Triticum). The past ~1600 years shall be analysed in particularly high temporal resolution (~25 to ~50 years). The project will allow to analyse the timing of agricultural activity, e.g., how long it took until cereal farming was introduced to the different Baltic Sea areas reflected by the selected sites, or when phases of particularly intensive agricultural activity occurred. Differences in the timing of the introduction of cereal farming in coastal areas and in the hinterland shall be assessed by comparison with already published terrestrial records. The project will also contribute to a better understanding of synchronous changes in terrestrial ecosystems, such as deforestation or migration of plant taxa over the past 6000 years. By applying different methods of climate reconstruction, the climatic frame conditions of agricultural activity can be assessed. Moreover, since marine sediments shall be analysed, coeval changes in aquatic ecosystems can be identified by the examination of aquatic palynomorphs. Thus, it can be found out if agricultural activity influenced the marine realm, e.g. via increased nutrient input. Data generated by collaborators (e.g. diatom- and foraminifer-based datasets) shall be included in the analyses.High sedimentation rates in the basins where the sites have been drilled guarantee that an appropriate temporal resolution can be achieved. Pilot studies during IODP-Expedition-347 onshore party and in the framework of ongoing projects have shown that palynomorphs are very well-preserved at the different sites, and that sediments from one of the northern sites contain chironomid remains in excellent preservation. The results of the proposed study will significantly contribute to a more detailed view on the development and impact of agricultural activity and of environment and climate dynamics in the Baltic Sea region.