Responses of Arctic permafrost peatlands to climate changes over the past millennia
Northern circumpolar permafrost peatlands store ~300 Pg of organic carbon (C), and play a critical role in regulating global biogeochemical cycles. Amplified warming in high-latitude regions is threatening this large C stock, because permafrost thawing will expose previously frozen C to decompositio...
Main Author: | |
---|---|
Other Authors: | , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
Helsingin yliopisto
2018
|
Subjects: | |
Online Access: | http://hdl.handle.net/10138/241222 |
id |
ftunivhelsihelda:oai:helda.helsinki.fi:10138/241222 |
---|---|
record_format |
openpolar |
spelling |
ftunivhelsihelda:oai:helda.helsinki.fi:10138/241222 2023-08-20T04:04:53+02:00 Responses of Arctic permafrost peatlands to climate changes over the past millennia Zhang, Hui Swindles, Graeme University of Helsinki, Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme Helsingin yliopisto, bio- ja ympäristötieteellinen tiedekunta Helsingfors universitet, bio- och miljövetenskapliga fakulteten 2018-09-06T12:10:25Z application/pdf http://hdl.handle.net/10138/241222 eng eng Helsingin yliopisto 978-951-51-4457-7 http://hdl.handle.net/10138/241222 URN:ISBN:978-951-51-4457-7 Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. Opinnäyte Text Doctoral dissertation (article-based) Artikkeliväitöskirja Artikelavhandling doctoralThesis 2018 ftunivhelsihelda 2023-07-28T06:27:53Z Northern circumpolar permafrost peatlands store ~300 Pg of organic carbon (C), and play a critical role in regulating global biogeochemical cycles. Amplified warming in high-latitude regions is threatening this large C stock, because permafrost thawing will expose previously frozen C to decomposition. Permafrost thaw-induced hydrological changes together with warming will influence plant photosynthesis and decomposition processes and thus C accumulation patterns. However, it is still unresolved how C accumulation, warming and associated hydrological changes are interlinked. In this study, I used 14 peat records from four sites in northeast European Russia and Finnish Lapland to reconstruct permafrost peatland vegetation, hydrology and C dynamics. The studied records were dated by radiocarbon (14C) and lead (210Pb) methods. In order to reconstruct hydrology, i.e. water-table depth (WTD), I first developed a new modern testate amoeba-WTD training set. The training set represented different habitats and comprised 145 surface peat samples collected from the four study sites. The training set data were then applied to six peat records to reconstruct last millennium hydrological changes. Plant macrofossil analysis was also conducted for these six cores to study changes in the vegetation, habitat conditions and permafrost dynamics, and to evaluate testate amoeba-based WTD reconstructions. In order to calculate and model C accumulation patterns, bulk density and C content (occasionally loss on ignition) analyses were carried out for 14 cores. C modelling enabled the C capacity analyses of peat that was accumulated during recent centuries vs. older peat layers. Several environmental variables, such as nitrogen (N) content, C/N ratio, WTD, plant functional types and summer temperature were used to evaluate allogenic C accumulation forcing in the past. The data show that testate amoebae are powerful indicators of hydrological conditions in permafrost peatlands. Testate amoeba and plant macrofossil reconstructions suggest ... Doctoral or Postdoctoral Thesis Arctic permafrost Lapland Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto Arctic |
institution |
Open Polar |
collection |
Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
op_collection_id |
ftunivhelsihelda |
language |
English |
description |
Northern circumpolar permafrost peatlands store ~300 Pg of organic carbon (C), and play a critical role in regulating global biogeochemical cycles. Amplified warming in high-latitude regions is threatening this large C stock, because permafrost thawing will expose previously frozen C to decomposition. Permafrost thaw-induced hydrological changes together with warming will influence plant photosynthesis and decomposition processes and thus C accumulation patterns. However, it is still unresolved how C accumulation, warming and associated hydrological changes are interlinked. In this study, I used 14 peat records from four sites in northeast European Russia and Finnish Lapland to reconstruct permafrost peatland vegetation, hydrology and C dynamics. The studied records were dated by radiocarbon (14C) and lead (210Pb) methods. In order to reconstruct hydrology, i.e. water-table depth (WTD), I first developed a new modern testate amoeba-WTD training set. The training set represented different habitats and comprised 145 surface peat samples collected from the four study sites. The training set data were then applied to six peat records to reconstruct last millennium hydrological changes. Plant macrofossil analysis was also conducted for these six cores to study changes in the vegetation, habitat conditions and permafrost dynamics, and to evaluate testate amoeba-based WTD reconstructions. In order to calculate and model C accumulation patterns, bulk density and C content (occasionally loss on ignition) analyses were carried out for 14 cores. C modelling enabled the C capacity analyses of peat that was accumulated during recent centuries vs. older peat layers. Several environmental variables, such as nitrogen (N) content, C/N ratio, WTD, plant functional types and summer temperature were used to evaluate allogenic C accumulation forcing in the past. The data show that testate amoebae are powerful indicators of hydrological conditions in permafrost peatlands. Testate amoeba and plant macrofossil reconstructions suggest ... |
author2 |
Swindles, Graeme University of Helsinki, Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme Helsingin yliopisto, bio- ja ympäristötieteellinen tiedekunta Helsingfors universitet, bio- och miljövetenskapliga fakulteten |
format |
Doctoral or Postdoctoral Thesis |
author |
Zhang, Hui |
spellingShingle |
Zhang, Hui Responses of Arctic permafrost peatlands to climate changes over the past millennia |
author_facet |
Zhang, Hui |
author_sort |
Zhang, Hui |
title |
Responses of Arctic permafrost peatlands to climate changes over the past millennia |
title_short |
Responses of Arctic permafrost peatlands to climate changes over the past millennia |
title_full |
Responses of Arctic permafrost peatlands to climate changes over the past millennia |
title_fullStr |
Responses of Arctic permafrost peatlands to climate changes over the past millennia |
title_full_unstemmed |
Responses of Arctic permafrost peatlands to climate changes over the past millennia |
title_sort |
responses of arctic permafrost peatlands to climate changes over the past millennia |
publisher |
Helsingin yliopisto |
publishDate |
2018 |
url |
http://hdl.handle.net/10138/241222 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic permafrost Lapland |
genre_facet |
Arctic permafrost Lapland |
op_relation |
978-951-51-4457-7 http://hdl.handle.net/10138/241222 URN:ISBN:978-951-51-4457-7 |
op_rights |
Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden. This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited. Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty. |
_version_ |
1774715306285989888 |