The impact of water table depth and decomposer community on DOC concentrations in soil water of a Nordic peatland
(2025) In Student thesis series INES NGEM01 20251Dept of Physical Geography and Ecosystem Science
- Abstract
- Drainage of peatlands causes changes in water table (WT), vegetation and decomposer community. As a consequence, decomposition patterns and carbon dynamics change, which is visible in altered Dissolved Organic Carbon (DOC) concentrations in ground and soil water. Additional changes in precipitation patterns towards more extreme drought and rain periods, as expected with climate change, cause further changes in peatland hydrology, especially affecting peatlands that have been drained.
In this thesis, the relationship between WT and DOC dynamics was investigated in a one-year field monitoring study. The field observations were complemented with an eight-week mesocosm experiment, including two different drying and rewetting patterns and the... (More) - Drainage of peatlands causes changes in water table (WT), vegetation and decomposer community. As a consequence, decomposition patterns and carbon dynamics change, which is visible in altered Dissolved Organic Carbon (DOC) concentrations in ground and soil water. Additional changes in precipitation patterns towards more extreme drought and rain periods, as expected with climate change, cause further changes in peatland hydrology, especially affecting peatlands that have been drained.
In this thesis, the relationship between WT and DOC dynamics was investigated in a one-year field monitoring study. The field observations were complemented with an eight-week mesocosm experiment, including two different drying and rewetting patterns and the addition of wood and wood-decomposing fungi to test the effects of decomposer community change. It was hypothesised that lowered WT would increase DOC concentrations, and even more so in the presence of wood and wood-decomposing fungi, which were expected to have an enhancing effect on DOC concentrations.
Field data showed a negative relation between DOC concentrations and WT that was more pronounced in the drained than in the pristine site, which was likely driven by increasing decomposition in periods with lower WT. This relationship was also visible in the mesocosm experiment, but only for the control treatments without wood addition. Mesocosms did not show higher DOC concentrations in treatments with added wood and fungi, but a stronger increase over time than the controls, irrespective of watering strategy. The most influential component in the experiment was time, followed by the presence or absence of wood or fungi.
The reasons are unknown, but likely effects are DOC production and pH alterations by the fungus, increased DOC production due to nutrient mining or the mobilisation of phenolic compounds from wood. These contrasting explanations call for further research about the role of decomposer communities in peatland DOC dynamics. (Less) - Popular Abstract
- Peatlands are critical for climate change mitigation due to their immense carbon storage capacity. However, when drained for human use, they become sources of carbon emissions, releasing CO₂ into the atmosphere and dissolved organic carbon (DOC) into water bodies. Climate change is expected to increase these losses in northern peatlands. Drainage also causes ecological shifts from open, moss-dominated wetlands to an increasing dominance of shrubs and trees. The shifts in hydrology and plant composition alter the microbial life that breaks down the organic matter, creating a favourable environment for fungi. As they are known for breaking down matter that bacteria can not access, introducing fungi into an environment can potentially... (More)
- Peatlands are critical for climate change mitigation due to their immense carbon storage capacity. However, when drained for human use, they become sources of carbon emissions, releasing CO₂ into the atmosphere and dissolved organic carbon (DOC) into water bodies. Climate change is expected to increase these losses in northern peatlands. Drainage also causes ecological shifts from open, moss-dominated wetlands to an increasing dominance of shrubs and trees. The shifts in hydrology and plant composition alter the microbial life that breaks down the organic matter, creating a favourable environment for fungi. As they are known for breaking down matter that bacteria can not access, introducing fungi into an environment can potentially increase the organic matter breakdown and DOC production.
This study investigated how lowered water tables and microbial community changes affect DOC release in a drained northern peatland. Combining a one-year field monitoring study with controlled lab experiments, we found that drained sites released more DOC than pristine peatlands, particularly during droughts. Surprisingly, while fungi did not immediately increase DOC in lab tests, they triggered a delayed rise in DOC concentrations, suggesting complex interactions between microbes and their environment. The new microbial composition might have effects in both directions: stabilisation of carbon and quicker release.
The findings highlight a growing threat: peatland carbon stocks are increasingly vulnerable in a warming climate. To predict the future of these carbon sinks, there is a need to further investigate the exact role of microbial communities in peatland carbon cycling. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9203894
- author
- Gaber, Johanna LU
- supervisor
- organization
- alternative title
- How drought and decomposers influence carbon leaching from soils in peatlands
- course
- NGEM01 20251
- year
- 2025
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Physical Geography, Ecosystem Analysis, Biogeochemistry, Drought, Climate Change, Land-use
- publication/series
- Student thesis series INES
- report number
- 724
- language
- English
- id
- 9203894
- date added to LUP
- 2025-06-25 09:16:21
- date last changed
- 2025-06-25 09:16:21
@misc{9203894,
abstract = {{Drainage of peatlands causes changes in water table (WT), vegetation and decomposer community. As a consequence, decomposition patterns and carbon dynamics change, which is visible in altered Dissolved Organic Carbon (DOC) concentrations in ground and soil water. Additional changes in precipitation patterns towards more extreme drought and rain periods, as expected with climate change, cause further changes in peatland hydrology, especially affecting peatlands that have been drained.
In this thesis, the relationship between WT and DOC dynamics was investigated in a one-year field monitoring study. The field observations were complemented with an eight-week mesocosm experiment, including two different drying and rewetting patterns and the addition of wood and wood-decomposing fungi to test the effects of decomposer community change. It was hypothesised that lowered WT would increase DOC concentrations, and even more so in the presence of wood and wood-decomposing fungi, which were expected to have an enhancing effect on DOC concentrations.
Field data showed a negative relation between DOC concentrations and WT that was more pronounced in the drained than in the pristine site, which was likely driven by increasing decomposition in periods with lower WT. This relationship was also visible in the mesocosm experiment, but only for the control treatments without wood addition. Mesocosms did not show higher DOC concentrations in treatments with added wood and fungi, but a stronger increase over time than the controls, irrespective of watering strategy. The most influential component in the experiment was time, followed by the presence or absence of wood or fungi.
The reasons are unknown, but likely effects are DOC production and pH alterations by the fungus, increased DOC production due to nutrient mining or the mobilisation of phenolic compounds from wood. These contrasting explanations call for further research about the role of decomposer communities in peatland DOC dynamics.}},
author = {{Gaber, Johanna}},
language = {{eng}},
note = {{Student Paper}},
series = {{Student thesis series INES}},
title = {{The impact of water table depth and decomposer community on DOC concentrations in soil water of a Nordic peatland}},
year = {{2025}},
}