The effects of restoration on biodiversity, water quality and greenhouse gas fluxes in a rich fen peatland

Rich fens are globally significant wetlands due to their high biodiversity and provision of multiple ecosystem services, such as water purification and climate mitigation. However, many U.K. rich fens have become botanically degraded. This is principally due to abandonment, following the cessation of management (mowing/grazing) and has led to a decline in plant species richness. Although the response to mowing on plant species richness has been well documented across Europe, there is no prior knowledge of this research being undertaken at U.K rich fens. Additionally, the effects of mowing on water quality are largely unquantified. Furthermore, the spatial heterogeneity of greenhouse gases across and within botanically rich and botanically poor sites is also unknown. Two rich fen plant communities: Cladio-Molinietum (n=9) and Scheonus nigricans - Juncus subnodulosus (n=8) were examined across three sites; chosen for their conservation value and current degraded condition. A 50 % success rate was achieved following mowing to increase species richness, which meant assumptions were not met for both plant communities. Nitrate, phosphate and dissolved organic carbon concentrations did not reduce following mowing, however there was a beneficial increase in concentration of base cations at both sites. The greenhouse gas investigation revealed that the net gaseous carbon flux between both sites was comparable, which did not meet expectations that the botanically impoverished site would have higher carbon emissions, however, expected differences between plant communities were observed at both sites. Therefore, this study shows the complexity of the botanical, hydro-chemical and greenhouse gas spatial heterogeneity at rich fens. Careful examination prior to restoration is needed to determine whether environmental/ecological barriers have been removed, so that restoration is not in any way inhibited. In addition, this study has demonstrated that objectives for biodiversity may be in conflict with objectives to manage for other ecosystem services, in these multi-functional wetlands

Final report on project SP1210: Lowland peatland systems in England and Wales – evaluating greenhouse gas fluxes and carbon balances

Lowland peatlands represent one of the most carbon-rich ecosystems in the UK. As a result of widespread habitat modification and drainage to support agriculture and peat extraction, they have been converted from natural carbon sinks into major carbon sources, and are now amongst the largest sources of greenhouse gas (GHG) emissions from the UK land-use sector. Despite this, they have previously received relatively little policy attention, and measures to reduce GHG emissions either through re-wetting and restoration or improved management of agricultural land remain at a relatively early stage. In part, this has stemmed from a lack of reliable measurements on the carbon and GHG balance of UK lowland peatlands. This project aimed to address this evidence gap via an unprecedented programme of consistent, multi year field measurements at a total of 15 lowland peatland sites in England and Wales, ranging from conservation managed ‘near-natural’ ecosystems to intensively managed agricultural and extraction sites. The use of standardised measurement and data analysis protocols allowed the magnitude of GHG emissions and removals by peatlands to be quantified across this heterogeneous data set, and for controlling factors to be identified. The network of seven flux towers established during the project is believed to be unique on peatlands globally, and has provided new insights into the processes the control GHG fluxes in lowland peatlands. The work undertaken is intended to support the future development and implementation of agricultural management and restoration measures aimed at reducing the contribution of these important ecosystems to UK GHG emissions

The effects of restoration on biodiversity, water quality and greenhouse gas fluxes in a rich fen peatland

Rich fens are globally significant wetlands due to their high biodiversity and provision of multiple ecosystem services, such as water purification and climate mitigation. However, many U.K. rich fens have become botanically degraded. This is principally due to abandonment, following the cessation of management (mowing/grazing) and has led to a decline in plant species richness. Although the response to mowing on plant species richness has been well documented across Europe, there is no prior knowledge of this research being undertaken at U.K rich fens. Additionally, the effects of mowing on water quality are largely unquantified. Furthermore, the spatial heterogeneity of greenhouse gases across and within botanically rich and botanically poor sites is also unknown. Two rich fen plant communities: Cladio-Molinietum (n=9) and Scheonus nigricans - Juncus subnodulosus (n=8) were examined across three sites; chosen for their conservation value and current degraded condition. A 50 % success rate was achieved following mowing to increase species richness, which meant assumptions were not met for both plant communities. Nitrate, phosphate and dissolved organic carbon concentrations did not reduce following mowing, however there was a beneficial increase in concentration of base cations at both sites. The greenhouse gas investigation revealed that the net gaseous carbon flux between both sites was comparable, which did not meet expectations that the botanically impoverished site would have higher carbon emissions, however, expected differences between plant communities were observed at both sites. Therefore, this study shows the complexity of the botanical, hydro-chemical and greenhouse gas spatial heterogeneity at rich fens. Careful examination prior to restoration is needed to determine whether environmental/ecological barriers have been removed, so that restoration is not in any way inhibited. In addition, this study has demonstrated that objectives for biodiversity may be in conflict with objectives to manage for other ecosystem services, in these multi-functional wetlands

Hydro-chemical effects following restoration mowing in two rich fen plant communities

Mowing is a common management technique employed in Europe and North America to manage seral wetland plant communities to: (a) prevent development to late succession, (b) minimise internal eutrophication and (c) conserve biodiversity. However, little is known about the effect mowing has on water quality, and the duration of any effects. Therefore, mowing treatments were applied in two abandoned fen plant communities: a Schoenus nigricans-Juncus subnodulosus (SN) community (hand-cutting) and a Cladio-Molinietum (CM) community (machine mowing). Mowing took place once in each community across three sites in North Wales, U.K. Effects on water chemistry were followed for two years post mowing. Mowing led to a rise in water table towards the ground surface in the CM plant community, persisting throughout the duration of the study. Increases in electrical conductivity, pH, calcium and magnesium concentrations were observed in both plant communities following mowing for two years. This represents a positive impact on fen hydro-chemistry, promoting base rich conditions favoured by calcicolous plants, however it may be a result of peat compaction and or disturbance. Contrary to expectations, mowing did not lead to a reduction in nutrient or dissolved organic carbon (DOC) concentration in either plant community. The CM community exhibited a short-term increase in DOC and dissolved organic nitrogen, which decreased by the second year. It is suggested that these changes were attributable to increased litter inputs. Both plant communities exhibited an increased in base cations, pH and electrical conductivity. It appears that any disturbance to the carbon and nitrogen cycles may be short-lived following mowing, whereas the increased availability of base-rich cations and associated increase of pH and electrical conductivity may confer longer term ecological benefits

Lowland peatland systems in England and Wales – evaluating greenhouse gas fluxes and carbon balances

Lowland peatlands represent one of the most carbon-rich ecosystems in the UK. As a result of widespread habitat modification and drainage to support agriculture and peat extraction, they have been converted from natural carbon sinks into major carbon sources, and are now amongst the largest sources of greenhouse gas (GHG) emissions from the UK land-use sector. Despite this, they have previously received relatively little policy attention, and measures to reduce GHG emissions either through re-wetting and restoration or improved management of agricultural land remain at a relatively early stage. In part, this has stemmed from a lack of reliable measurements on the carbon and GHG balance of UK lowland peatlands. This project aimed to address this evidence gap via an unprecedented programme of consistent, multi-year field measurements at a total of 15 lowland peatland sites in England and Wales, ranging from conservation-managed ‘near-natural’ ecosystems to intensively managed agricultural and extraction sites. The use of standardised measurement and data analysis protocols allowed the magnitude of GHG emissions and removals by peatlands to be quantified across this heterogeneous dataset, and for controlling factors to be identified. The network of seven flux towers established during the project is believed to be unique on peatlands globally, and has provided new insights into the processes the control GHG fluxes in lowland peatlands. The work undertaken is intended to support the future development and implementation of agricultural management and restoration measures aimed at reducing the contribution of these important ecosystems to UK GHG emissions