Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming
The changes in lake diatom assemblages as a response to climate warming over the past three decades were examined in 26 lakes across Northwestern Finnish Lapland using multivariate statistical techniques. The lakes are distributed along a steep climatic and vegetational gradient, covering three dist...
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ftunivhelsihelda:oai:helda.helsinki.fi:10138/332007 2023-08-20T04:10:14+02:00 Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming Courroux, Maxime Helsingin yliopisto, Bio- ja ympäristötieteellinen tiedekunta University of Helsinki, Faculty of Biological and Environmental Sciences Helsingfors universitet, Bio- och miljövetenskapliga fakulteten 2021 application/pdf http://hdl.handle.net/10138/332007 eng eng Helsingin yliopisto University of Helsinki Helsingfors universitet URN:NBN:fi:hulib-202106303251 http://hdl.handle.net/10138/332007 palaeolimnology Finnish Lapland climate change diatoms Ympäristömuutoksen ja globaalin kestävyyden maisteriohjelma Master's Programme in Environmental Change and Global Sustainability Magisterprogrammet i miljöförändringar och global hållbarhet Ympäristömuutos Environmental Change Miljöförändring pro gradu -tutkielmat master's thesis pro gradu-avhandlingar 2021 ftunivhelsihelda 2023-07-28T06:24:54Z The changes in lake diatom assemblages as a response to climate warming over the past three decades were examined in 26 lakes across Northwestern Finnish Lapland using multivariate statistical techniques. The lakes are distributed along a steep climatic and vegetational gradient, covering three distinct vegetation zones spanning boreal coniferous forest, mountain birch woodland, and treeless tundra. Lakes were selected following a study realised by Weckström and Korhola in 2001, who had sampled the same lakes for surface-sediment diatom assemblages, physical, and chemical limnological variables. Climate data from the past 30 years was retrieved, showing a slow and steady yearly increase in temperature, with strong seasonal fluctuation and fall months experiencing the strongest warming. Surface sediment samples were taken from the lakes and their diatom communities analysed. A total of 185 diatom taxa representing 27 genera were recorded. Ordination techniques (DCA, CCA) at the genus and species level were performed to identify the main patterns of variation between diatom data from the original data set and the current study, and their relationship to environmental variables. Strong changes were recorded in four of the lakes with major shifts in dominant diatom species. Moderate changes were recorded in eight lakes, where dominance changes were recorded for a few species while the majority remained unchanged. The remaining 14 lakes did not show noticeable changes over the 30-year period. Changes observed in the studied lakes did not follow a widely observed pattern in northern Hemisphere lakes. The results indicate that while climate change is a driving factor behind changing lake dynamics with increasing temperatures and decreasing lake ice cover duration, it cannot be the only force responsible. Master Thesis Tundra Lapland Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto Changing Lake ENVELOPE(-45.619,-45.619,-60.708,-60.708) Korhola ENVELOPE(26.190,26.190,67.446,67.446) |
institution |
Open Polar |
collection |
Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
op_collection_id |
ftunivhelsihelda |
language |
English |
topic |
palaeolimnology Finnish Lapland climate change diatoms Ympäristömuutoksen ja globaalin kestävyyden maisteriohjelma Master's Programme in Environmental Change and Global Sustainability Magisterprogrammet i miljöförändringar och global hållbarhet Ympäristömuutos Environmental Change Miljöförändring |
spellingShingle |
palaeolimnology Finnish Lapland climate change diatoms Ympäristömuutoksen ja globaalin kestävyyden maisteriohjelma Master's Programme in Environmental Change and Global Sustainability Magisterprogrammet i miljöförändringar och global hållbarhet Ympäristömuutos Environmental Change Miljöförändring Courroux, Maxime Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming |
topic_facet |
palaeolimnology Finnish Lapland climate change diatoms Ympäristömuutoksen ja globaalin kestävyyden maisteriohjelma Master's Programme in Environmental Change and Global Sustainability Magisterprogrammet i miljöförändringar och global hållbarhet Ympäristömuutos Environmental Change Miljöförändring |
description |
The changes in lake diatom assemblages as a response to climate warming over the past three decades were examined in 26 lakes across Northwestern Finnish Lapland using multivariate statistical techniques. The lakes are distributed along a steep climatic and vegetational gradient, covering three distinct vegetation zones spanning boreal coniferous forest, mountain birch woodland, and treeless tundra. Lakes were selected following a study realised by Weckström and Korhola in 2001, who had sampled the same lakes for surface-sediment diatom assemblages, physical, and chemical limnological variables. Climate data from the past 30 years was retrieved, showing a slow and steady yearly increase in temperature, with strong seasonal fluctuation and fall months experiencing the strongest warming. Surface sediment samples were taken from the lakes and their diatom communities analysed. A total of 185 diatom taxa representing 27 genera were recorded. Ordination techniques (DCA, CCA) at the genus and species level were performed to identify the main patterns of variation between diatom data from the original data set and the current study, and their relationship to environmental variables. Strong changes were recorded in four of the lakes with major shifts in dominant diatom species. Moderate changes were recorded in eight lakes, where dominance changes were recorded for a few species while the majority remained unchanged. The remaining 14 lakes did not show noticeable changes over the 30-year period. Changes observed in the studied lakes did not follow a widely observed pattern in northern Hemisphere lakes. The results indicate that while climate change is a driving factor behind changing lake dynamics with increasing temperatures and decreasing lake ice cover duration, it cannot be the only force responsible. |
author2 |
Helsingin yliopisto, Bio- ja ympäristötieteellinen tiedekunta University of Helsinki, Faculty of Biological and Environmental Sciences Helsingfors universitet, Bio- och miljövetenskapliga fakulteten |
format |
Master Thesis |
author |
Courroux, Maxime |
author_facet |
Courroux, Maxime |
author_sort |
Courroux, Maxime |
title |
Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming |
title_short |
Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming |
title_full |
Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming |
title_fullStr |
Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming |
title_full_unstemmed |
Changes in lake diatom assemblages in Northwestern Finnish Lapland over recent decades and their relation to climate warming |
title_sort |
changes in lake diatom assemblages in northwestern finnish lapland over recent decades and their relation to climate warming |
publisher |
Helsingin yliopisto |
publishDate |
2021 |
url |
http://hdl.handle.net/10138/332007 |
long_lat |
ENVELOPE(-45.619,-45.619,-60.708,-60.708) ENVELOPE(26.190,26.190,67.446,67.446) |
geographic |
Changing Lake Korhola |
geographic_facet |
Changing Lake Korhola |
genre |
Tundra Lapland |
genre_facet |
Tundra Lapland |
op_relation |
URN:NBN:fi:hulib-202106303251 http://hdl.handle.net/10138/332007 |
_version_ |
1774724292110450688 |