Silke Oldorff - Academia.edu (original) (raw)
Address: LfU
Landesamt für Umwelt Brandenburg
Naturpark Stechlin-Ruppiner Land
Friedensplatz 9
16775 Stechlin OT Menz
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Papers by Silke Oldorff
For the first time, evidence of a submerged pine forest from the early Holocene can be documented... more For the first time, evidence of a submerged pine forest from the early Holocene can be documented in a central European lake. Subaquatic tree stumps were discovered in Lake Giesenschlagsee at a depth of between 2 and 5 m using scuba divers, side‐scan sonar and a remotely operated vehicle. Several erect stumps, anchored to the ground by roots, represent an in situ record of this former forest. Botanical determination revealed the stumps to be Scots pine (Pinus sylvestris) with an individual tree age of about 80 years. The trees could not be dated by means of dendrochronology, as they are older than the regional reference chronology for pine. Radiocarbon ages from the wood range from 10 880±210 to 10 370±130 cal. a BP, which is equivalent to the mid‐Preboreal to early Boreal biozones. The trees are rooted in sedge peat, which can be dated to this period as well, using pollen stratigraphical analysis. Tilting of the peat bed by 4 m indicates subsidence of the ground due to local dead ice melting, causing the trees to become submerged and preserved for millennia. Together with recently detected Lateglacial in situ tree occurrences in nearby lakes, the submerged pine forest at Giesenschlagsee represents a new and highly promising type of geo‐bio‐archive for the wider region. Comparable in situ pine remnants occur at some terrestrial (buried setting) and marine (submerged setting) sites in northern central Europe and beyond, but they partly differ in age. In general, the in situ pine finds document shifts of the zonal boreal forest ecosystem during the late Quaternary.
This study tested the setup of an exclosure experiment to exclude or at least diminish direct imp... more This study tested the setup of an exclosure experiment to exclude or at least diminish direct impacts of medium-to large size benthivorous fishes on submerged macrophytes in three EU habitat type 3140 lakes in NE-Germany. In lakes Großer Glietzen and Peetsch no effect on stimulation of regrowth of macrophytes could be observed, the exclosures remained free of macrophyte vegetation like the reference plots. This is likely caused by water level fluctuations resulting in lake bottom conditions unsuitable for macrophyte development. Only in Lake Stechlin significant differences of macrophyte development between inside and outside the exclosure have been observed in 2014 and 2015. The ratio of covered vs. uncovered sediment was significantly influenced by presence or absence of benthivorous fishes. Also the ratio of charophytes vs. angiosperms and other groups was significantly influenced. In 2014 and 2015 Charophytes dominated the macrophyte vegetation inside the exclosure, while at the reference plot in 2014 angiosperms dominated and in 2015 significantly increased. The experiment results support the hypothesis, that benthivorous fishes are key species and strongly influencing macrophyte communities. Additionally species-specific direct impacts of certain benthivorous fishes on macrophytes are documented from direct observations.
26.-29.09.2015 we investigated several secondary (former exctraction sites) standing waters in No... more 26.-29.09.2015 we investigated several secondary (former exctraction sites) standing waters in Northrhine-Westphalia using the scuba diving method and assessing favourable conservation status according to the Habitats Directive. Beside that, data on neobiota have been noted.
Naturschutz und Sporttauchen im Naturpark-Stechlin-Ruppiner Land
Zusammenfassung: Der Beitrag umfasst eine Beschreibung und Analyse historischer anthropogener Bel... more Zusammenfassung: Der Beitrag umfasst eine Beschreibung und Analyse historischer anthropogener Belastungsquellen des Großen Stechlinsees (Nord-Brandenburg), dessen Einzugsgebiet überwiegend bewaldet ist. Daten zu ausgewählten stofflichen Belastungen seit Mitte der 1940er bis zum Anfang des 21. Jahrhunderts werden vorgestellt und in Ihrer Wirkung auf den Nährstoffhaushalt des Sees bewertet. Der tatsächliche Umfang einiger dieser Belastungen wird nach dieser Analyse als deutlich schwerwiegender als bislang angenommen eingeschätzt. Mit einem einfachen Modell wird die Wirkung des externen Phosphoreintrags auf die seeinterne Phosphorkonzentration ermittelt. Danach sind die externen Belastungen ein durchaus wesentlicher Bestandteil der aktuellen ökologischen Defizite. Vor dem Hintergrund der Entwicklung von Mitigationsstrategien gegenüber dem Klimawandel sind daher bei negativen Wasserbilanzen anthropogene Faktoren kritischer zu bewerten.
For the first time, evidence of a submerged pine forest from the early Holocene can be documented... more For the first time, evidence of a submerged pine forest from the early Holocene can be documented in a central European lake. Subaquatic tree stumps were discovered in Lake Giesenschlagsee at a depth of between 2 and 5 m using scuba divers, side‐scan sonar and a remotely operated vehicle. Several erect stumps, anchored to the ground by roots, represent an in situ record of this former forest. Botanical determination revealed the stumps to be Scots pine (Pinus sylvestris) with an individual tree age of about 80 years. The trees could not be dated by means of dendrochronology, as they are older than the regional reference chronology for pine. Radiocarbon ages from the wood range from 10 880±210 to 10 370±130 cal. a BP, which is equivalent to the mid‐Preboreal to early Boreal biozones. The trees are rooted in sedge peat, which can be dated to this period as well, using pollen stratigraphical analysis. Tilting of the peat bed by 4 m indicates subsidence of the ground due to local dead ice melting, causing the trees to become submerged and preserved for millennia. Together with recently detected Lateglacial in situ tree occurrences in nearby lakes, the submerged pine forest at Giesenschlagsee represents a new and highly promising type of geo‐bio‐archive for the wider region. Comparable in situ pine remnants occur at some terrestrial (buried setting) and marine (submerged setting) sites in northern central Europe and beyond, but they partly differ in age. In general, the in situ pine finds document shifts of the zonal boreal forest ecosystem during the late Quaternary.
This study tested the setup of an exclosure experiment to exclude or at least diminish direct imp... more This study tested the setup of an exclosure experiment to exclude or at least diminish direct impacts of medium-to large size benthivorous fishes on submerged macrophytes in three EU habitat type 3140 lakes in NE-Germany. In lakes Großer Glietzen and Peetsch no effect on stimulation of regrowth of macrophytes could be observed, the exclosures remained free of macrophyte vegetation like the reference plots. This is likely caused by water level fluctuations resulting in lake bottom conditions unsuitable for macrophyte development. Only in Lake Stechlin significant differences of macrophyte development between inside and outside the exclosure have been observed in 2014 and 2015. The ratio of covered vs. uncovered sediment was significantly influenced by presence or absence of benthivorous fishes. Also the ratio of charophytes vs. angiosperms and other groups was significantly influenced. In 2014 and 2015 Charophytes dominated the macrophyte vegetation inside the exclosure, while at the reference plot in 2014 angiosperms dominated and in 2015 significantly increased. The experiment results support the hypothesis, that benthivorous fishes are key species and strongly influencing macrophyte communities. Additionally species-specific direct impacts of certain benthivorous fishes on macrophytes are documented from direct observations.
26.-29.09.2015 we investigated several secondary (former exctraction sites) standing waters in No... more 26.-29.09.2015 we investigated several secondary (former exctraction sites) standing waters in Northrhine-Westphalia using the scuba diving method and assessing favourable conservation status according to the Habitats Directive. Beside that, data on neobiota have been noted.
Naturschutz und Sporttauchen im Naturpark-Stechlin-Ruppiner Land
Zusammenfassung: Der Beitrag umfasst eine Beschreibung und Analyse historischer anthropogener Bel... more Zusammenfassung: Der Beitrag umfasst eine Beschreibung und Analyse historischer anthropogener Belastungsquellen des Großen Stechlinsees (Nord-Brandenburg), dessen Einzugsgebiet überwiegend bewaldet ist. Daten zu ausgewählten stofflichen Belastungen seit Mitte der 1940er bis zum Anfang des 21. Jahrhunderts werden vorgestellt und in Ihrer Wirkung auf den Nährstoffhaushalt des Sees bewertet. Der tatsächliche Umfang einiger dieser Belastungen wird nach dieser Analyse als deutlich schwerwiegender als bislang angenommen eingeschätzt. Mit einem einfachen Modell wird die Wirkung des externen Phosphoreintrags auf die seeinterne Phosphorkonzentration ermittelt. Danach sind die externen Belastungen ein durchaus wesentlicher Bestandteil der aktuellen ökologischen Defizite. Vor dem Hintergrund der Entwicklung von Mitigationsstrategien gegenüber dem Klimawandel sind daher bei negativen Wasserbilanzen anthropogene Faktoren kritischer zu bewerten.
This book is a photographic field guide for submerged freshwater macrophytes. It describes 140 sp... more This book is a photographic field guide for submerged freshwater macrophytes. It describes 140 species from Germany, Austria and Switzerland in German language.