Restoration

Assessment: understanding the site before intervening

A key first step in peatland restoration is a comprehensive assessment of the site conditions.^[1],[2] By monitoring and analyzing the site conditions, restoration practitioners can identify the prominent stressors, quantify their impacts, and develop goals to restore the site. The assessment should describe the current conditions and, if possible, the pre-degraded functioning of the site.^[1]

Pre-degradation conditions

Determining pre-degradation conditions of a peatland provides an idea of the undisturbed functioning of the site. Knowing the site’s undegraded condition allows restorationists to set targets and determine how restoration can be evaluated. In general, pre-degradation information can be derived from two sources:

Palaeoecology - micro and macro-fossils found in the peat can be used to reconstruct historic ecological interactions between biota and the respective environments.^[3]

Historical records - maps, satellite images, photos, taxonomic collections, and written and oral accounts can provide insight into the historical functioning of the site.^[4],[1],[2]

There are several limitations with acquiring and interpreting this information. First, there is often minimal information on the historical conditions of peatlands. This is especially true in areas with long histories of anthropogenic land-use change (e.g., Central Europe), making it difficult to acquire an accurate idea of the original peatland functioning.^[5] If information is available, the pre-degraded state may no longer be achievable. For example, soil conditions in extracted peatlands often differ significantly from the original conditions, making rewetting an unviable restoration option.^[6] Restoration should therefore focus not on restoring historical conditions, but rather on using knowledge of these conditions to restore the achievable function of the peatland.^[7]

Current conditions

Determining the current conditions of a degraded peatland requires an assessment of three key components: hydrology, peat, and vegetation. These variables are interdependent, meaning a change in one causes a change in the other two.^[8],[9] The hydrology influences which plants will grow; the plants, in turn, determine the type of peat that forms; and the structure and type of peat regulates the flow and storage of water in the peatland.^[2] By assessing each of these components, restoration practitioners can determine the extent to which the peatland is degraded and develop clear and achievable restoration goals.

Hydrology

Altered hydrology is the primary problem to address in peatland restoration, and thus the most important step in assessing a degraded peatland.^[8] Key parameters to measure are the water table level and water table fluctuations throughout the site,^[8],[2] as these characteristics determine the status of the peat layer and the vegetation on-site.^[10] The hydrology assessment should also record the amount and type of precipitation, the presence of drainage structures (e.g., ditches, pipes), topography (e.g., slope, microtopography), and the direction of water flow.

The hydrologic regime of peatlands is rarely isolated from the surrounding area. External factors, like upslope agricultural areas with drainage tiles or irrigation lines, can disrupt the groundwater influx to the peatland. Any hydrological restoration to the degraded peatland will be ineffective unless the off-site issues are addressed. Hydrological assessments should therefore incorporate the greater catchment area, including land-use and associated drainage networks.^[8],[5],[11]

Water quality and chemistry parameters (e.g., pH, electrical conductivity) should also be measured, as these conditions influence which plants occur and the peat that accumulates.^[12] For example, if the groundwater is acidic with a pH < 5, restoring the site towards bog conditions is more realistic and feasible than towards fen conditions.^[1] These parameters should be measured both at the degraded site and, for groundwater-fed peatlands (i.e., fens, swamps), at the groundwater source.

Peat

An assessment of the peatlayer is important, as it provides insight into the peatland functioning and what restoration options can improve this function. Thin decomposed peat layers, associated with drained peatlands, have a lower water storage capacity, making the establishment of water-reliant species such as Sphagnum mosses less likely.^[1] Further, decomposition can reduce the distance between the sub-peat soil and the surface layer, favouring the establishment of non-peatland plant species. By measuring peat parameters, restoration practitioners can determine the level of degradation and the feasibility of different restoration options (e.g., re-establishing the Sphagnum community). Important peat parameters to measure include the degree of decomposition (using the Von Post scale; see Box X), water content, surface level changes, and peat erosion.^[13]

In addition to physical properties of peat, chemical analysis of nutrient concentrations can provide further insight into peatland functioning. Degraded peatlands near agricultural areas are often extremely nutrient-rich, due to peat mineralisation, use of chemical fertilisers, and manure from livestock.^[8] Rewetting of a nutrient-rich peatland can cause internal eutrophication, a process in which anoxic conditions associated with the high water table lead to the mobilisation of nutrients bound to the peat layer,^[7] favouring the establishment of fast-growing, non-peatland plant species.^[8] Nutrient analysis should incorporate the greater catchment area to determine if external nutrient enrichment will continue.

Vegetation

A vegetation assessment provides further insight into the peatland condition and function. As it is generally not feasible to conduct an inventory of all plants on site, indicator species are often monitored to obtain a representative assessment of the peatland vegetation with less sampling intensity.^[8] If indicator species associated with peatlands (e.g., Sphagnum spp. for bogs or Carex spp. for fens) are present, restoration to conditions that support these species is more likely to be achievable. Species associated with drier conditions (e.g., ericaceous shrubs) indicate a disruption of the water table.^[14] If invasive species are present (e.g., Spiraea tomentosa, an invasive species that threatens bog communities in Europe)^[15], restoration decisions should incorporate management of these species.

In addition to on-site vegetation, the viability and composition of the seed bank should be monitored to understand the potential of natural vegetation following restoration (i.e., rewetting).^[8] If the seed bank on site is not viable, supplementary vegetation management will likely be required as a part of the restoration plan. The assessment of live vegetation and the seedbank should incorporate the degraded peatland and the larger area. For example, if invasive species are identified off-site, their potential impact on restoration should be considered. Additionally, desirable vegetation and seed banks in the surrounding area can serve as donor material for restoration that requires planting or sowing of seeds.^[1]

Assessment integration: identifying stressors and degradation level

The data collected during the assessment of site conditions can be compiled and analysed to determine the primary stressors, their negative effects on peatland functioning, and ultimately the level of degradation on-site. Degraded peatlands are often impacted by multiple, interacting stressors. For example, agricultural land use can lead to drainage of peatlands and nutrient enrichment, each requiring different considerations during restoration.

When evaluating the impact of stressors, it is important to consider that peat, hydrology, and vegetation react to degradation at different rates.^[8] In a drained peatland, hydrology and vegetation experience immediate impacts, with aquatic plant species being unable to survive in the dry conditions, while peat decomposes slowly with less immediate impacts. Considering the differing responses of peat, hydrology, and vegetation to different stressors during the site assessment provides practitioners with the necessary information to begin the restoration planning process.

Planning and design

Upon identification of the stressors affecting a peatland and their extent, restoration planning can begin. This is a critical phase, as it defines the project vision, while identifying potential problems and conflicts that might be encountered along the way.^[4],[19],[1] Developing a restoration plan is a complex process, requiring engagement with stakeholders, definition of clear goals and objectives, prioritization of restoration options, and effective baseline data. Incorporating these components into the planning phase sets the stage for effective peatland restoration.

Stakeholder engagement

Peatland restoration requires balancing, in addition to ecological objectives, socioeconomic, cultural, and legal considerations. Therefore, effective planning of restoration projects is dependent on engagement with stakeholders who have an investment in the project outcome.^[8] For a list of common stakeholder groups that should be engaged during restoration projects, along with reasons for engagement, see Table X.

Further, effective restoration requires continuous engagement throughout the entire process, not just during the planning phase. Communication channels with stakeholders established early on must be well-maintained and prepared for an adaptive approach. This ensures that unforeseen conditions can be quickly addressed, minimizing project delays.

Goals and objectives

Before restoration treatments, practitioners must determine what the project is trying to achieve. Two levels of target are defined in peatland restoration:

• Goals are general statements indicating the desired medium to long-term ecological or socioeconomic restoration outcomes of the project (e.g., “restore a functioning, peat-forming mire community”; “Reduce GHG emissions on site by X%”).^[4]
• Objectives are well-defined, precise statements focused on measurable parameters which outline how the goal(s) will be achieved (e.g., “raise the mean annual water table to within 20 cm of the surface across 80% of the restoration site within five years of intervention”).^[17]

Setting goals and objectives requires developing a reference model: a conceptual framework that provides a quantitative representation of the conditions a site could exhibit if it were not degraded. Reference models compile information from multiple sources, including physical reference sites, historical conditions, current conditions, and stakeholder engagement.^[4] As reference models do not aim to describe the past conditions of a site, but rather the potential conditions that would exist if restoration were achieved, factors that could impact the site’s future functioning (e.g., climate change) can be incorporated. With a well-developed reference model, desired post-restoration conditions can be established and realistic goals and objectives can be formulated to ensure effective restoration.^[1],[7]

Setting realistic and effective goals and objectives requires consultation with stakeholders to navigate and avoid conflicts.^[8] To facilitate consultation, goals and objectives are often kept simple to ensure stakeholders understand and can effectively contribute to the goal-setting process.^[17] Common goal themes in European peatland restoration include climate change mitigation, biodiversity conservation, productivity (i.e., paludiculture), and water quality improvement, and flood control.^[8] Goals can focus on specific, measurable ecological conditions or more broadly on ecosystem services (Figure x from Section 1.2).

Prioritisation

When the restoration potential of a site exceeds the available budget or feasible intervention area, goals must be ranked by priority.^[8] For a large, highly degraded peatland, it may not be feasible to restore the entire area, requiring prioritisation of restoration treatments and goals. Restoring highly degraded sites is more costly than restoring moderately degraded sites; thus, a project with a large budget is likely to have greater restoration effectiveness targeting more degraded areas. Conversely, smaller budget projects can still achieve restoration by targeting moderately degraded areas where the required effort is lower and restoration is more cost-effective.^[11] The complexity of prioritising restoration goals necessitates a dynamic approach. A case-by-case evaluation should be done for each project to determine the best course of restorative action using knowledge of the site, well-developed reference models, and engagement with stakeholders.

Restoration plan

After clear goals and objectives have been established and prioritised, they are formalised in a restoration plan. A well-developed plan is critical for achieving project outcomes^[19],[1] while supporting cost-effective restoration by helping to avoid inefficient field work. A restoration plan should include the following:

• Site description — location, boundary, topography, hydrology, soil, fauna, flora, current land use, stakeholders, stressors, and level of degradation;
• Goals and objectives — desired outcomes with clearly defined, measurable benchmarks;
• Restoration measures — specific treatments, maps, schedules, materials, contractors, and budgets;
• Monitoring plan — protocols, indicators, measurement thresholds, and responsibilities;
• Maintenance plan — ongoing work required to prevent site regression post-treatment.

The restoration plan should be considered a living document that will change and evolve throughout the project.^[19] Incorporation of adaptive management, the systematic process of using feedback from the environment to continuously adjust and improve management strategies,^[4] ensures that the plan is constantly evolving.

Baseline monitoring

The final step before restoration measures can begin is to conduct baseline monitoring. This provides a point of comparison, both for assessing pre-restoration conditions against the reference model and for comparing pre-restoration and post-restoration conditions. Having these comparisons is necessary for measuring the effectiveness of restoration and communicating project development to stakeholders. As pre-restoration conditions will be compared to post-restoration conditions, baseline monitoring should focus on measurable indicators which will determine if desired restoration outcomes have been achieved.^[4],[1] For guidance on monitoring design and parameter selection, see Section 2.5.

Implementation

Monitoring and evaluation

Monitoring plays a crucial role in the post-implementation phase of restoration projects, as it serves to determine whether restoration targets have been met.^[8],[13] Without a comprehensive monitoring plan, it is not possible to conclude the effectiveness of restoration, as there is no point of comparison between the restored peatland and the desired conditions. By developing a robust monitoring plan, restoration practitioners can determine the efficacy of treatments and adapt or modify approaches to better achieve the desired outcomes.^{[16],[8],[20]} This could include, for example, adjusting management practices or modifying the project goals and objectives. Monitoring also helps determine whether funds were spent effectively,^[8] allowing for improved restoration planning and funding allocation in future projects.

Monitoring design

The monitoring program should be designed during the planning phase, before any restoration treatments are implemented,^[10] and should be based on established goals to ensure monitoring parameters are effective indicators of restoration efficacy.^[20] For example, a project intended to increase biodiversity or the presence of endangered peatland species will have different indicators than one aimed at GHG reduction. To further ensure that monitoring parameters are appropriately defined, protocols should be formulated through consultation with experts and utilize scientifically supported methods.^[20] While some desired outcomes of peatland restoration are immediate (e.g., changing the water table level), others (e.g., re-establishment of a functioning peat-forming ecosystem) may take years to decades.^[5] Long-term monitoring may be required to evaluate the complete outcomes of restoration treatments. Due to these long-term requirements, protocols should be systematic and standardized to allow for continuity of monitoring by different individuals and parties, as responsibilities are likely to change throughout the restoration process.^[20]

Typically, monitoring is divided into two phases: pre-restoration and post-restoration monitoring. Pre-restoration, or baseline monitoring, occurs before restoration treatments to serve as a reference point for the initial site’s functioning and is a foundational component of the monitoring plan. Post-restoration monitoring occurs after restoration treatments and is compared with baseline levels to determine the extent to which restoration targets are being reached.

Experimental design

To allow for effective evaluation of restoration impacts, monitoring plans should follow an experimental design. A standard experimental design for monitoring ecological restoration projects is the Before-After Control-Impact (BACI) protocol.^[4] In a BACI design, monitoring indicators are measured before and after restoration treatments on the restoration site, and at a control site with no treatments. This provides two points of reference: the pre-restoration baseline (how the site functioned before restoration) and the control site trajectory (separating observed restoration effects from natural variability). BACI designs should have adequate spatial replication at the restoration and control sites to allow for a more robust determination of restoration impacts by separating them from other effects.^[20]

Monitoring parameters

Peatland restoration monitoring parameters depend on various factors, including the peatland status and associated goals^[16] or the available financial and technical resources.^[21] These factors, in combination with the multitude of potential monitoring parameters, make monitoring programs highly project-specific. To address the ambiguity involved in selecting appropriate monitoring indicators, the European Commission, Directorate-General for Environment have provided recommendations for harmonized peatland monitoring protocols.^[22] Although these parameters and protocols were developed for assessing peatland condition generally, they still serve as relevant indicators for measuring the efficacy of restoration. For a list of mandatory parameters directly relevant to peatland restoration, see Table x.

In addition to these indicators, the restoration treatments should be monitored to ensure proper functioning. As treatments for restoring peatlands primarily aim to achieve rewetting, monitoring the function of restoration treatments often involves assessing the condition of water control structures (e.g., dams, bunds).^[8]

As monitoring is dependent on the project budget, restoration practitioners should consider the long-term costs of desired monitoring techniques. Low-budget restoration projects should use low-cost techniques to enable effective monitoring. Projects with larger budgets can consider higher-cost monitoring techniques, provided they are beneficial for evaluating restoration outcomes. Examples of low and high-cost monitoring techniques are shown in Table X. As incorporating replicates increases monitoring costs, the optimal number of replicates should balance maximal benefits and minimal costs.^[16]

Monitoring considerations

The timing of monitoring can, for some parameters, significantly alter the results. For example, if groundwater discharge has been identified as an indicator parameter, measurements should be taken when conditions are dry.^[8] Thus, consideration should be given to the temporal influence on the variability of monitoring data.

This webpage is not intended to be an exhaustive list of all monitoring techniques for restoration, but rather to inform restoration practitioners of key concepts to consider when designing a monitoring plan. Consideration of these factors will allow for more effective evaluation of peatland restoration. For more comprehensive documents outlining specific monitoring parameters and protocols, see Šefferová Stanová (2025).^[22]

Data collection

Monitoring is the basis for determining whether restoration targets have been reached. Thus the data collected during this process is critical to ensure reliable conclusions can be made. Methods for data collection should be clearly outlined in the monitoring plan and follow standardized and systematic protocols to ensure quality assurance and standards are upheld throughout the data collection process. Having well-defined protocols can allow for easy training of monitoring responsibilities throughout the restoration project and help prevent against observation bias.^[20]

Equally important to well-defined protocols and training for data collection is developing an extensive data management plan to ensure the collected data can effectively support the evaluation process. A data management plan should cover file formats and structures, and outline file backup and data redundancy protocols.^[20] Ensuring that data is collected and managed according to pre-established protocols will contribute to effective long-term project evaluation.

Evaluation

The data collected during monitoring are analyzed to determine the extent to which restoration targets are being reached by comparing post-restoration conditions with pre-restoration conditions, control-site conditions, and/or reference-model conditions. Šefferová Stanová (2025) recommends using the distance from the reference condition as a measure of restoration success.^[22] The distance from the reference condition is defined as the difference between a variable’s measured value and its reference level (i.e., the desired value established during the planning phase). This framework provides tangible values that restoration practitioners can use to determine the efficacy of restoration efforts.

Another widely used technique for evaluating restoration outcomes is the 5-star system paired with the ecological recovery wheel, recommended by Gann et al. (2019).^[4] These tools provide a systematic framework for comparing site conditions to a reference model to assess the effectiveness of restoration. Note that the 5-star system and the Ecological Recovery Wheel should be adapted to the respective restoration project.

Determining how well targets were met allows practitioners to assess the efficacy of restoration, and whether funding was well spent.^[8] Determining which treatments were or were not effective will enable enhanced selection of restoration treatments in future projects, leading to more effective spending. In addition to evaluating the impacts of restoration, the monitoring plan and protocols should also be assessed.^[20] Restoration practitioners should consider whether monitoring is providing the information required to evaluate restoration impacts to determine whether technical adjustments to the monitoring program are required to assess restoration outcomes more effectively. The outcomes of the restoration treatment evaluation will determine whether management interventions are needed.

Ongoing Management

Restored peatlands, like most restoration sites, will often require some level of ongoing management after treatments to prevent the site from regressing into a degraded state.^[4] The level of ongoing management required will depend on various factors, including the characteristics of the restoration site, the present stressors, and the available funding. Ongoing management can include either pre-scheduled preventative maintenance or adaptive management, which is determined based on the monitoring results.

Management Activities

Preventative Maintenance

Preventative maintenance activities are pre-scheduled interventions aimed at preventing the site from slipping into a degraded state. They should be included in the monitoring and maintenance plan, which is developed through consultation with local stakeholders. Maintenance protocols and costs should also be outlined in this plan. Examples include:

• Maintenance of water control structures to ensure appropriate water levels are maintained on-site.^[8]
• Removal of undesired vegetation to encourage the establishment and succession of desired peatland species. The removal of encroaching trees and shrubs can be beneficial for short-term restoration when rewetting has not been successful due to drought.^[23] However, removal of encroaching shrubs and trees has also been linked to increased seedlings in the cleared area due to the greater light availability and the surface peat acting as an effective germination medium.^[24]
• Mowing to assist with the regrowth of peatland specialist species while suppressing the growth of other dominant, undesired species. Worth noting, mowing with large machinery can also reduce habitat heterogeneity of restored peatlands by destroying microtopography, leading to losses of rare species that require heterogeneity.^[25]

The above examples of preventative maintenance illustrate the complexity of peatland management, with no consistent management protocols applying to all restoration projects. Preventative management techniques should be carefully selected with the ultimate goal of establishing passive restoration, in which the natural conditions are restored and the site becomes self-regulating.^[8]

Adaptive Management

Adaptive management is the process of evaluating information gained during monitoring to continuously work towards desired restoration outcomes by employing new management techniques.^[4] When monitoring indicates that the restoration trajectory is deviating from targets, adaptive management serves as a framework to determine the best course of action to achieve restoration targets. This process supports restoration while simultaneously gaining insight into the efficacy of various restoration treatment and management techniques.