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Holocene pattern of organic carbon accumulation in a small lake in Estonia

100%

Punning J. M., Koff T., Sakson M., Kangur M.

Polish Journal of Ecology

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2007

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tom 55

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nr 1

A comprehensive study of the sediment profile of L. Viitna Linajärv, a small closed drainage lake located in northern Estonia (59°27´N, 25°01´E), was conducted to assess the impact of water-level changes on the carbon accumulation dynamics in the lake during the Holocene. The variations of the P content, C/N ratio, fossil pigments and diatom communities indicate essential changes in the lake ecosystem history during the Holocene. The results show that on millennial time-scale (103 years) fluctuations of the lake level, concurrent shore erosion and coprecipitation of dissolved organic matter with allochthonous mineral particles were the driving factors in the lake history. Net organic carbon accumulation was ~30 g m–2 yr–1 at the beginning of the Holocene (ca 9000 BP), then decreased to 10 g m–2 yr–1 (5000–2000 BP) and increased in the upper layers (since 1000 BP) up to 60 g m–2 yr–1.

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Ecosystem response to early and late Holocene lake-level changes in Lake Juusa, Southern Estonia

100%

Koff T., Punning J. M., SDarmaja-Korjonen K., Martma T.

Polish Journal of Ecology

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2005

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tom 53

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nr 4

The main aim of the study is to analyse the response of the catchment and lake ecosystem to the lake-level change on the basis of pollen, macrofossil, cladoceran and stable isotope records obtained by a comprehensive study of sediments from a shore core from Lake Juusa (Southern Estonia). The obtained multi-proxy data indicate that there is good correspondence between lithological, macrofossil and cladoceran changes during most time in the studied period. The palaeorecords show that the development of the Lake Juusa ecosystem was triggered mainly by the fluctuations of the lake level. Discrepancies of the data for some periods are caused by the concurrent processes having specific impact on the obtained records.

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Human impact on the ecosystem of Lake Ruusmae [Southern Estonia] traced in the sediments

100%

Punning J. M., Koff T., Sakson M., Terasmaa J.

Polish Journal of Ecology

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2004

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tom 52

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nr 3

Long-term limnological monitoring data (from 1971 to 2001) and the documented human load history were compared with sediment core record in a small lake Ruusmäe in southern Estonia. It was established that pollen data reflect the main land-use changes on the catchment rather adequately. The response of other palaeoecological indicators (fossil pigments, carbon and nitrogen, phosphorous) and diatom composition to the changes in the nutrient input from the nearby large cattle-breeding centre took some time. When the load had exceeded certain limit, the transition of the lake from eutrophic to hypertrophic state took place very quickly. Simultaneously with the reorganisation of matter cycling rapid changes occurred in the diatom community, in which species characteristic of hypertrophic lakes became dominant. Irrespective of the drastic drop in the external load at the beginning of the 1990s the changes in the biogeochemical matter cycling and diatom community are modest.

Ograniczanie wyników

3 Polish Journal of Ecology

3 Koff T.

3 Punning J. M.

2 Sakson M.

1 Kangur M.

1 Martma T.

1 SDarmaja-Korjonen K.

1 Terasmaa J.

1 2007

1 2005

1 2004

Holocene pattern of organic carbon accumulation in a small lake in Estonia

Ecosystem response to early and late Holocene lake-level changes in Lake Juusa, Southern Estonia

Human impact on the ecosystem of Lake Ruusmae [Southern Estonia] traced in the sediments