A late Holocene record of land-use history, soil erosion, lake trophy and lake-level fluctuations at Bj�resj�sj�n (south Sweden)

Abstract

Land-use history, soil ersosion, lake trophy and lake-level fluctuations during the last 3000 years were reconstructed through a multidisciplinary palaeolimnological study (pollen, plant macrofossils, diatoms, physical and chemical analysis, magnetic measurements and radiometric methods) of a small eutrophic lake in southern Sweden (Bj~resjOsjOn, Scania). There are striking responses in diatom, chemical, sediment yield and magnetic records to land-use changes documented by pollen analysis or historical sources, and to lake-level changes identified from sedimentary changes. Our multidisciplinary approach assists interpretation of the processes controlling long-term changes and separation of the effects of different factors (land-use changes, lake-level fluctuations) on individual biostratigraphical records. Climate has controlled processes in the lake indirectly, through lake-level fluctuations, from the Late Bronze Age to the Viking Age (700 BC-AD 800). Since the Viking Age, land-use controlled most of the changes observed in the lake's development and soil erosion processes. Major changes in lake development occurred during the last 200 years, due to a drastic increase in soil erosion and water eutrophication during a period of agricultural modernization.

Comparing mineral magnetic properties of sediments in two reservoirs in “strongly” and “mildly” eroded regions on the Guizhou Plateau, southwest China: A tool for inferring differences in sediment sources and soil erosion

“…Dearing et al, 1986;Foster et al, 1986;Dai et al, 2009). As already demonstrated in previous studies elsewhere, when erosion is relatively weak and/or only limited in surface soils or sheeting erosion is prevailing, the magnetic components abundant in topsoil (particularly the fine SP and relatively fine SSD grains) may dominate the magnetic materials moved into water bodies (Gaillard et al, 1991). Although the relative proportions of the SSD grains are not high in the surface horizons and instead increase with depth in the soil profiles sampled from Shibanqiao and Xiaohe Catchments, the SSD grains are still likely to be enriched in the sediments deposited when erosion is weak and limited in topsoil or only splash and sheet erosion happen as rainfall and/or overland flow may preferentially move these relatively fine grains rather than the relatively coarse magnetic grains into the reservoirs.…”

Effects of historical land use on sediment yield from a lacustrine watershed in central Chile

“…Additional findings show that our estimates of sediment yield contain little uncertainty from the third assumption-that all the sediment deposited in the lake, organic as well as inorganic, comes from the watershed, not from the lake (Dearing, 1991;Gaillard et al, 1991b). First, as shown above (see Sediment yield in Results section), organic matter in Chica San Pedro Lake, though of largely unknown source, has little effect on estimated trends in sediment yield because the organic content is nearly constant (Figures 2H and 3B).…”

Fifty years of Quaternary pollen analysis in Fennoscandia 1954–2004

“…Seppä & Weckströ m 1999, Rosén et al 2001, Bigler et al 2002, Seppä et al 2002a), integrated studies on human impact, land-use, and prehistoric and recent agriculture on lake trophic status and sedimentation (e.g. Gaillard et al 1991, Bradshaw 2001, and investigations on the effects of Picea immigration, landuse, and forest fires on lake-water pH and dissolved organic carbon (e.g. Renberg et al 1993, Korsman et al 1994, Korsman & Segerströ m 1998.…”