The Holocene paleolimnology of Lake Sämbosjön,southwestern Sweden

The Holocence paleolimnology of Lake Sämbosjön is described using geochemical and diatom analyses. The objective of this study is the reconstruction of major changes in trophic state and productivity, and to interpret the major causative processes. The accumulation of organic matter indicates a relatively high productivity in early Holocene, and the diatom analysis indicates a relatively high trophic state and pH. A succeeding decrease in productivity and trophic state and lowering in pH is recorded from about 8000 BP. If lake development had been primarily edaphically conditioned, viz. determined by nutrient supply from catchment soils, such a progressive oligotrophication would represent the common development of temperate lakes. Between about 6000 BP and 4000 BP Lake Sämbosjön was characterized by relatively stable productivity and pH. From about 4000 BP the analyses reveal an increase again in trophic state, productivity, and in pH. This eutrophication, which continued throughout the late Holocene, was caused by an exceptionally strong human influence on the catchment of Lake Sämbosjön. The increased supply of nutrients from cleared and deforested catchment soils changed the trophic state and provided the basis for increased lake productivity.