3000 Years of past regional and local land-use and land-cover change in the southeastern Swedish coastal area: Early human-induced increases in landscape openness as a potential nutrient source to the Baltic Sea coastal waters

Reconstructions of past land use and related land-cover changes at local and regional scales are needed to evaluate the potential long-term impacts of land use on the coastal waters of the Baltic Sea. In this purpose, we selected the Gamleby area at the Swedish Baltic Sea coast for a case study. We use a new, high resolution pollen record from a small lake (Lillsjon) located 3.6 km NNW of the bay Gamlebyviken and detailed analysis of the available archeological data to reconstruct local land-use changes over the last 3000 years. To estimate land-cover change at local (2-3 km radius area) and regional (50 km radius area) scales we use four additional, published pollen records from two small and two large lakes (25-70 km S of Lillsjon) and the Landscape Reconstruction Algorithm, a pollen-vegetation modeling scheme. Results show that regional and local (small lakes Lillsjon and Hyttegol) land-cover changes are comparable over the last 1500 years (Late Iron Age to present), and that landscape openness was much larger locally than regionally (difference of 20-40% cover over the last 500 years). The periods of largest potential impacts on the Gamlebyviken Bay from regional and local land use are 200-950 CE (Late Iron Age) and 1450 CE to present, and of lowest potential impacts 950-1450 CE. The question on whether the large landscape openness 1150-50 BCE and significant afforestation 50 BCE-200 CE reconstructed for Lillsjon's area are characteristic of the Gamlebyviken region will require additional pollen records in the catchment area.