title: The importance of catchment vegetation for alkalinity, phosphorus burial and macrophytes as revealed by a recent paleolimnological study in a soft water lake.
abstract: The land use within a catchment may markedly affect the environmental conditions in a lake and the storage capability of its sediments. This study investigated how changes in the dominant catchment vegetation (from local stands of deciduous trees over extensive heathland with some agriculture to mainly coniferous forest) occurring during the last ca. 200years were reflected in the sediments of a soft water lake and how these changes influenced the lake ecosystem. Pollen, macrofossils, metals, different phosphorus (P) forms, organic matter, carbon and nitrogen contents were determined in short sediment cores. This novel combination of proxies revealed that 1) the reduction of deciduous trees in the watershed seemingly reduced the calcium (Ca) supply to the lake and thereby its buffering capacity. This development was accompanied by decreased abundances of Ca-dependent species and subsequent increases in acidophilic species. 2) The sedimentary contents of organic matter, non-reactive P and humic-bound P were evidently higher in sediments deposited during the time when deciduous trees were abundant, which is probably linked to a stabilising effect by Ca. 3) An erosion event clearly reduced the amounts of macrofossils of isoetid species and characeans, indicating a reduction in their maximum distribution depth because of lower water transparency. Overall, the results of our paleolimnological study are of importance within lake management by convincingly showing how land use changes may (irreversibly) affect environmental conditions and species composition in soft water lakes and the storage of organic matter and P in their sediments.
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. Electronic address: amklamt@biology.sdu.dk.
authors.forename: Anna-Marie
authors.initials: AM
authors.lastname: Klamt
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. Electronic address: hsj@biology.sdu.dk.
authors.forename: Henning S
authors.initials: HS
authors.lastname: Jensen
authors.affiliation: Environmental Archaeology and Materials Science, The National Museum of Denmark, I. C. Modewegs Vej, 2800 Kongens Lyngby, Denmark. Electronic address: morten.fischer.mortensen@natmus.dk.
authors.forename: Morten F
authors.initials: MF
authors.lastname: Mortensen
authors.affiliation: Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark. Electronic address: nos@ign.ku.dk.
authors.forename: Norman
authors.initials: N
authors.lastname: Schreiber
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. Electronic address: reitzel@biology.sdu.dk.
authors.forename: Kasper
authors.initials: K
authors.lastname: Reitzel
keywords: (31)P NMR spectroscopy; Inositol phosphate; Land use changes; Lobelia lake; Sequential phosphorus extraction; Total lead profile