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Spatiotemporal variation of net methane emissions and its causes across an ombrotrophic peatland : a site study from Southern Sweden

Lindgren, Amelie LU (2013) In Student thesis series Ines NGEM01 20131
Dept of Physical Geography and Ecosystem Science
Abstract
Methane emissions from natural wetlands are an important contributor to methane levels in the atmosphere. These emissions are highly variable in time and space, even within sites. Further understanding of this variation is vital to successfully model the overall methane emissions from wetlands. This study investigates spatial variation through measurements of 22 plots across Fäjemyr bog. Manual measurements were taken in 16 plots across four sites at the bog during five days throughout November 2012. In addition 6 automatic chambers were used that measures emissions once every hour throughout the year. The emissions from these 6 automatic chambers were also used for assessing the temporal variation during the year 2012. The spatial... (More)
Methane emissions from natural wetlands are an important contributor to methane levels in the atmosphere. These emissions are highly variable in time and space, even within sites. Further understanding of this variation is vital to successfully model the overall methane emissions from wetlands. This study investigates spatial variation through measurements of 22 plots across Fäjemyr bog. Manual measurements were taken in 16 plots across four sites at the bog during five days throughout November 2012. In addition 6 automatic chambers were used that measures emissions once every hour throughout the year. The emissions from these 6 automatic chambers were also used for assessing the temporal variation during the year 2012. The spatial variation was found to depend upon microtopography more than site location. Plot-specific variation was also found, which suggests that other variables also affect spatial variation. The temporal variation was generally best explained by temperature at soil depths of 20 and 50 cm, especially if daily averages were used. The importance of temporal scale became evident when correlations between net methane emissions and environmental variables changed depending on the time investigated. Yearly, seasonal and shorter timescales revealed different responses which were thought to depend on the seasonality of light and plant phenology at Fäjemyr in addition to the measured variables. Shorter timescales could be used to increase the process understanding of Fäjemyr. In addition, the study also reveals that the automatic chamber system poorly represents the methane emissions from hollows across the bog as emissions were lower than those measured in the manual plots. Emissions from lawns and hummocks seem to be better represented. (Less)
Abstract (Swedish)
Naturliga metanutsläpp sker från våra våtmarker världen över. Metan produceras naturligt genom nedbrytning i de syrefria förhållanden som en våtmark erbjuder. För att bättre kunna modellera och skala upp hur mycker metan som faktiskt släpps ut från dessa våtmarker måste ytterligare förståelse skapas över varför metanutsläppen varierar så kraftigt både i tid och rum. Denna studie försöker öka förståelsen för dessa variationer genom att följa både utsläpp och olika variabler så som temperatur, vattennivå, markfuktighet, lufttryck, och ljus för fotosyntes för at se hur de samvarierar på Fäjemyr, Skåne. Samt hur skillnader i rum, så som växtligthet och mikrotopografi påverkar utsläppens storlek i varje undersökt plot. För att mäta metan har 22... (More)
Naturliga metanutsläpp sker från våra våtmarker världen över. Metan produceras naturligt genom nedbrytning i de syrefria förhållanden som en våtmark erbjuder. För att bättre kunna modellera och skala upp hur mycker metan som faktiskt släpps ut från dessa våtmarker måste ytterligare förståelse skapas över varför metanutsläppen varierar så kraftigt både i tid och rum. Denna studie försöker öka förståelsen för dessa variationer genom att följa både utsläpp och olika variabler så som temperatur, vattennivå, markfuktighet, lufttryck, och ljus för fotosyntes för at se hur de samvarierar på Fäjemyr, Skåne. Samt hur skillnader i rum, så som växtligthet och mikrotopografi påverkar utsläppens storlek i varje undersökt plot. För att mäta metan har 22 kammare använts. 16 av dessa har placerats runt om Fäjemyr under November månad 2012, medan 6 kammare ingår i ett automatiskt system som mäter utsläpp en gång i timmen under året. Dessa 6 kammare användes för att titta på den temporala variationen, medan alla kammare användes i den spatiala analysen. Främst var det skillnader i mikrotopografi som bidrog till skillnader i storleken på utsläpp. Vegetationen gav inget klart resultat i denna studie, men det är troligt att både vegetation och andra variabler påverkar. Skillnader över tid förklarades generellt bäst när utsläppen korrelerades med marktemperaturer på 20 och 50 cm djup, sambandet blev generellt starkare vid användning av dygnsmedelvärden av utsläpp. Betydelsen av temporal skala blev tydlig i denna studie då flera olika tidsperspektiv studerades. Olika variabler blev mer eller mindre viktiga för utsläppen beroende på temporal skala. Det är troligt att den bästa processförståelsen ges om kortare tidsskalor används. Vid längre tidsskalor påverkar nämligen både ljus och fenologi förutom temperatur och hydrologi. Utöver studien av spatiotemporal variation kan även slutsatsen dras att utsläppen uppmätta i fem av sex kammrar i det automatiska systemet överenstämmer väl med de som uppmättes på andra delar av myren, detta gäller dock inte kammare tre, vars resultat visar betydligt lägre siffror än korrensponderande mätningar från övriga delar av myren. (Less)
Please use this url to cite or link to this publication:
author
Lindgren, Amelie LU
supervisor
organization
course
NGEM01 20131
year
type
H2 - Master's Degree (Two Years)
subject
keywords
temporal variation, spatial variation, Methane, geography, physical geography, ombrotrophic peatland
publication/series
Student thesis series Ines
report number
283
language
English
id
4001550
date added to LUP
2013-08-26 11:42:24
date last changed
2013-08-26 11:42:24
@misc{4001550,
  abstract     = {Methane emissions from natural wetlands are an important contributor to methane levels in the atmosphere. These emissions are highly variable in time and space, even within sites. Further understanding of this variation is vital to successfully model the overall methane emissions from wetlands. This study investigates spatial variation through measurements of 22 plots across Fäjemyr bog. Manual measurements were taken in 16 plots across four sites at the bog during five days throughout November 2012. In addition 6 automatic chambers were used that measures emissions once every hour throughout the year. The emissions from these 6 automatic chambers were also used for assessing the temporal variation during the year 2012. The spatial variation was found to depend upon microtopography more than site location. Plot-specific variation was also found, which suggests that other variables also affect spatial variation. The temporal variation was generally best explained by temperature at soil depths of 20 and 50 cm, especially if daily averages were used. The importance of temporal scale became evident when correlations between net methane emissions and environmental variables changed depending on the time investigated. Yearly, seasonal and shorter timescales revealed different responses which were thought to depend on the seasonality of light and plant phenology at Fäjemyr in addition to the measured variables. Shorter timescales could be used to increase the process understanding of Fäjemyr. In addition, the study also reveals that the automatic chamber system poorly represents the methane emissions from hollows across the bog as emissions were lower than those measured in the manual plots. Emissions from lawns and hummocks seem to be better represented.},
  author       = {Lindgren, Amelie},
  keyword      = {temporal variation,spatial variation,Methane,geography,physical geography,ombrotrophic peatland},
  language     = {eng},
  note         = {Student Paper},
  series       = {Student thesis series Ines},
  title        = {Spatiotemporal variation of net methane emissions and its causes across an ombrotrophic peatland : a site study from Southern Sweden},
  year         = {2013},
}