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https://doi.org/10.48548/pubdata-1388
| Resource type | Dissertation |
| Title(s) | Assessing the effects of peatland restoration |
| DOI | 10.48548/pubdata-1388 |
| Handle | 20.500.14123/1453 |
| Creator | Hammerich, Jenny  0009-0002-4727-1417 (Fakultät Nachhaltigkeit, Leuphana Universität Lüneburg  02w2y2t16) |
| Referee | Luthardt, Vera  1059793881von Wehrden, Henrik 0000-0003-2087-5552Schrautzer, Joachim 1023627949 |
| Advisor | Luthardt, Vera 1059793881 von Wehrden, Henrik 0000-0003-2087-5552 |
| Abstract | Naturally functioning peatlands, referred to as ‘mires’, are of high biodiversity value and fulfil a wide range of ecosystem functions, such as landscape-scale water regulation or the long-term storage of carbon and nutrients. Due to drainage, mainly for agriculture and forestry, more than 95% of German peatlands are degraded, resulting in the loss of biodiversity and the vital ecosystem functions of mires. Therefore, in a time of anthropogenic climate change and biodiversity loss, restoration efforts have increased in the past few decades, and international programmes and policies have progressively recognised the importance of peatland restoration. A central part of restoration is monitoring to evaluate success, inform on restoration outcomes and adapt restoration practices. However, the monitoring of peatland restoration is not standardised, and a methodology to assess mire-specific biodiversity is missing. Raising the water table, re-establishing peat accumulation and peatlands as carbon sinks, enhancing mire-specific biodiversity and saving GHG emissions are central goals of peatland restoration, but collectively analysed monitoring data is scarce. Although peatland restoration was found to enhance peatland ecosystem functioning and biodiversity, the outcome is not comparable to pristine mires, and factors influencing restoration success remain unclear. Therefore, this thesis presents the results of three studies: In Study I, a user-friendly, robust indicator system to assess mire-specific biodiversity is developed for north-east Germany, encompassing the different levels of mire-specific biodiversity and enabling an overall assessment. Value scales to rate mire-specific biodiversity in six categories are derived based on data from 30 study sites. To ensure robustness, the indicator system assessment is compared with assessments made by experts and practitioners. The comparison shows high correspondence. Furthermore, a practical example is given, demonstrating the indicator system's use for restoration projects. In Study II, the results for total organic carbon content (TOC), total nitrogen content (TN), the C/N ratio, pH value and dry bulk density (BD) sampling, as well as a description of the structure of near-surface peats in six restored fens in north-east Germany before (2002–2004) and after (2019–2021) restoration, are presented. Following successful rewetting with a water table at the surface, TOC increased comparable to values of undisturbed peats. In addition, the C/N ratio increased, meaning a decrease in nutrient availability. BD decreased, and values of sedge-dominated sites were similar to undisturbed peats. The PH value remained stable over time. A new, slightly decomposed peat moss layer on top of the degraded peat in peat moss-dominated sites was determined, as well as a structural change in the degraded near-surface peat in sedge-dominated peatlands to a more homogenous sludge mass with larger re-aggregates. In Study III, the effects of peatland restoration on the water table, peat accumulation, mire-specific biodiversity and GHG emissions of 33 forest peatlands in north-east Germany are described. In peatlands drained by ditches, hydraulic restoration led to a rise in the water table and the peat-accumulating area, increased mire-specific biodiversity, and decreased estimated GHG emissions. Still, the highest positive values in all analysed parameters were rarely determined. In contrast, peatlands, not drained by ditches but showing early signs of degradation, were restored by management measures – in this context the removal of tall vegetation or upcoming trees, as well as forest restructuring in the peatland catchment area. These peatlands were in a better initial state and management measures did not significantly enhance but instead preserved pre-measure conditions. In general, groundwater-abstracting facilities in the peatland catchment area hindered restoration success. Principal component analysis showed that the acid-base-ratio and tropic conditions of the peatland before restoration, hydrogenetic mire type and peatland size were not correlated with restoration success. In contrast, years since restoration had a positive relation. By using an easily applicable monitoring methodology, including the newly developed indicator system, to assess mire-specific biodiversity, the effects of peatland restoration on central restoration aims were robustly evaluated. The results of this thesis highlight the importance of preserving all remaining mires, as restoring peatlands to near-natural conditions is rarely achieved in the short term. However, as peatland rewetting especially quickly raises the water table, leading to peat accumulating conditions, TOC values in near-surface peats comparable to values of undisturbed peats, estimated savings in GHG emissions and greater habitat heterogeneity, it is necessary to rewet all degraded peatland as one key factor in mitigating climate change and fighting biodiversity loss. Mire-specific species increase slightly and not significantly after restoration, but the determined lower nutrient availability is assumed to favour re-colonisation by mire-specific species in the long term. Management measures preserve pre-measure conditions within the study’s time frame. As the positive effects of forest restructuring in peatland catchment areas are estimated to be long-term, this approach should be implemented immediately and considered for still functioning mires in the context of reduced water availability due to climate change. The decrease in BD and the newly accumulated peat layers in peat moss-dominated peatlands indicate the development of a new acrotelm, an essential factor in restoring peatlands to self-regulating mires. In conclusion, peatland restoration enhances ecosystem functionality and biodiversity, thus enhancing peatlands' resilience against the negative influences of global warming, mitigating climate change, and fighting biodiversity loss. |
| Language | English |
| Keywords | Peatland; Restoration; Mire; Peat; Soil; Biodiversity; Vegetation; Carbon Storage |
| Date of defense | 2024-09-09 |
| Year of publication in PubData | 2024 |
| Publishing type | First publication |
| Date issued | 2024-10-08 |
| Creation context | Research |
| Granting Institution | Leuphana Universität Lüneburg |
| Published by | Medien- und Informationszentrum, Leuphana Universität Lüneburg |
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