The importance of deciduous forest for alkalinity, phosphorus burial and isoetid macrophytes as revealed by a recent paleo study in a soft water Lobelia Lake (Grane Langsø, Denmark)

Anna-Marie Klamt, Kasper Reitzel, Morten F. Mortensen, Norman Schreiber, Henning S. Jensen

Research output: Contribution to conference without publisher/journalConference abstract for conferenceResearch

Abstract

Lake Grane Langsø is characterized by nutrient-poor soft water with very high visibilities and hence contains rare isoetid species (such as Isoetes lacustris, Littorella uniflora and Lobelia dortmanna). Pollen data and old maps show that the dominating vegetation in the catchment area of Lake Grane Langsø changed during the last ca. 200 years from deciduous forest to open heathland with some agriculture and afterwards to coniferous forest. To determine the effects of these changes on the lake, macrofossils, metals and different phosphorus (P) forms were analyzed in dated short sediment cores from the deepest site of the lake. The proxies revealed diverse changes in the lake’s conditions and species composition: 1) The removal of deciduous trees seemingly reduced the calcium supply to Lake Grane Langsø and thereby the lake’s buffering capacity. This development is accompanied by decreased amounts in macrofossils of calcium (Ca)-sensitive species (as reflected in Daphnia ephippia and Cristatella mucedo statoblasts) and followed by increases in acidophilic species (as reflected in Juncus seeds and Sphagnum leaves). 2) The contents of organic material and organic P forms were clearly lower in sediments that were deposited during the period of least forest cover. Especially humic bound P seems to be positively related to the presence of deciduous trees which may be linked to a stabilizing effect of calcium. 3) An erosion event (as reflected in Cenococccum geophilum sclerotia) during the open-land period clearly reduced the amounts of macrofossils for Isoetes sp., Lobelia sp. and Characeans. This suggests a reduction in their maximum distribution depth because of enhanced influx of terrestrial material and subsequently reduced water transparencies. Overall this paleo-study underlines the sensitivity of nutrient-poor soft water lakes to changes in their catchments vegetation and their partial irreversible consequences and is therefore of importance for lake management.
Original languageEnglish
Publication dateAug 2016
Publication statusPublished - Aug 2016
Event33rd SIL Conference - Torino, Italy
Duration: 31. Jul 20165. Aug 2016

Conference

Conference33rd SIL Conference
CountryItaly
CityTorino
Period31/07/201605/08/2016

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deciduous forest
lake water
alkalinity
phosphorus
lake
deciduous tree
calcium
heathland
nutrient
vegetation
coniferous forest
rare species
forest cover
buffering
transparency
visibility
sediment core
vertical distribution
pollen
catchment

Cite this

@conference{a3977f5cac404b4a88f3631ce5339757,
title = "The importance of deciduous forest for alkalinity, phosphorus burial and isoetid macrophytes as revealed by a recent paleo study in a soft water Lobelia Lake (Grane Langs{\o}, Denmark)",
abstract = "Lake Grane Langs{\o} is characterized by nutrient-poor soft water with very high visibilities and hence contains rare isoetid species (such as Isoetes lacustris, Littorella uniflora and Lobelia dortmanna). Pollen data and old maps show that the dominating vegetation in the catchment area of Lake Grane Langs{\o} changed during the last ca. 200 years from deciduous forest to open heathland with some agriculture and afterwards to coniferous forest. To determine the effects of these changes on the lake, macrofossils, metals and different phosphorus (P) forms were analyzed in dated short sediment cores from the deepest site of the lake. The proxies revealed diverse changes in the lake’s conditions and species composition: 1) The removal of deciduous trees seemingly reduced the calcium supply to Lake Grane Langs{\o} and thereby the lake’s buffering capacity. This development is accompanied by decreased amounts in macrofossils of calcium (Ca)-sensitive species (as reflected in Daphnia ephippia and Cristatella mucedo statoblasts) and followed by increases in acidophilic species (as reflected in Juncus seeds and Sphagnum leaves). 2) The contents of organic material and organic P forms were clearly lower in sediments that were deposited during the period of least forest cover. Especially humic bound P seems to be positively related to the presence of deciduous trees which may be linked to a stabilizing effect of calcium. 3) An erosion event (as reflected in Cenococccum geophilum sclerotia) during the open-land period clearly reduced the amounts of macrofossils for Isoetes sp., Lobelia sp. and Characeans. This suggests a reduction in their maximum distribution depth because of enhanced influx of terrestrial material and subsequently reduced water transparencies. Overall this paleo-study underlines the sensitivity of nutrient-poor soft water lakes to changes in their catchments vegetation and their partial irreversible consequences and is therefore of importance for lake management.",
author = "Anna-Marie Klamt and Kasper Reitzel and Mortensen, {Morten F.} and Norman Schreiber and Jensen, {Henning S.}",
year = "2016",
month = "8",
language = "English",
note = "33rd SIL Conference ; Conference date: 31-07-2016 Through 05-08-2016",

}

The importance of deciduous forest for alkalinity, phosphorus burial and isoetid macrophytes as revealed by a recent paleo study in a soft water Lobelia Lake (Grane Langsø, Denmark). / Klamt, Anna-Marie; Reitzel, Kasper; Mortensen, Morten F.; Schreiber, Norman; Jensen, Henning S.

2016. Abstract from 33rd SIL Conference, Torino, Italy.

Research output: Contribution to conference without publisher/journalConference abstract for conferenceResearch

TY - ABST

T1 - The importance of deciduous forest for alkalinity, phosphorus burial and isoetid macrophytes as revealed by a recent paleo study in a soft water Lobelia Lake (Grane Langsø, Denmark)

AU - Klamt, Anna-Marie

AU - Reitzel, Kasper

AU - Mortensen, Morten F.

AU - Schreiber, Norman

AU - Jensen, Henning S.

PY - 2016/8

Y1 - 2016/8

N2 - Lake Grane Langsø is characterized by nutrient-poor soft water with very high visibilities and hence contains rare isoetid species (such as Isoetes lacustris, Littorella uniflora and Lobelia dortmanna). Pollen data and old maps show that the dominating vegetation in the catchment area of Lake Grane Langsø changed during the last ca. 200 years from deciduous forest to open heathland with some agriculture and afterwards to coniferous forest. To determine the effects of these changes on the lake, macrofossils, metals and different phosphorus (P) forms were analyzed in dated short sediment cores from the deepest site of the lake. The proxies revealed diverse changes in the lake’s conditions and species composition: 1) The removal of deciduous trees seemingly reduced the calcium supply to Lake Grane Langsø and thereby the lake’s buffering capacity. This development is accompanied by decreased amounts in macrofossils of calcium (Ca)-sensitive species (as reflected in Daphnia ephippia and Cristatella mucedo statoblasts) and followed by increases in acidophilic species (as reflected in Juncus seeds and Sphagnum leaves). 2) The contents of organic material and organic P forms were clearly lower in sediments that were deposited during the period of least forest cover. Especially humic bound P seems to be positively related to the presence of deciduous trees which may be linked to a stabilizing effect of calcium. 3) An erosion event (as reflected in Cenococccum geophilum sclerotia) during the open-land period clearly reduced the amounts of macrofossils for Isoetes sp., Lobelia sp. and Characeans. This suggests a reduction in their maximum distribution depth because of enhanced influx of terrestrial material and subsequently reduced water transparencies. Overall this paleo-study underlines the sensitivity of nutrient-poor soft water lakes to changes in their catchments vegetation and their partial irreversible consequences and is therefore of importance for lake management.

AB - Lake Grane Langsø is characterized by nutrient-poor soft water with very high visibilities and hence contains rare isoetid species (such as Isoetes lacustris, Littorella uniflora and Lobelia dortmanna). Pollen data and old maps show that the dominating vegetation in the catchment area of Lake Grane Langsø changed during the last ca. 200 years from deciduous forest to open heathland with some agriculture and afterwards to coniferous forest. To determine the effects of these changes on the lake, macrofossils, metals and different phosphorus (P) forms were analyzed in dated short sediment cores from the deepest site of the lake. The proxies revealed diverse changes in the lake’s conditions and species composition: 1) The removal of deciduous trees seemingly reduced the calcium supply to Lake Grane Langsø and thereby the lake’s buffering capacity. This development is accompanied by decreased amounts in macrofossils of calcium (Ca)-sensitive species (as reflected in Daphnia ephippia and Cristatella mucedo statoblasts) and followed by increases in acidophilic species (as reflected in Juncus seeds and Sphagnum leaves). 2) The contents of organic material and organic P forms were clearly lower in sediments that were deposited during the period of least forest cover. Especially humic bound P seems to be positively related to the presence of deciduous trees which may be linked to a stabilizing effect of calcium. 3) An erosion event (as reflected in Cenococccum geophilum sclerotia) during the open-land period clearly reduced the amounts of macrofossils for Isoetes sp., Lobelia sp. and Characeans. This suggests a reduction in their maximum distribution depth because of enhanced influx of terrestrial material and subsequently reduced water transparencies. Overall this paleo-study underlines the sensitivity of nutrient-poor soft water lakes to changes in their catchments vegetation and their partial irreversible consequences and is therefore of importance for lake management.

M3 - Conference abstract for conference

ER -