Emma Taylor, Mark Whiteman (Environment Agency), Ros Tratt, Phil Eades & Bryan Wheeler (Sheffield Wetland Ecologists)

Hydrology is a vital component of our peatlands which directly influences the vegetation community. The re-establishment of hydrological conditions, or in other words making them wet enough for bog plants and moss to thrive, is key for restoration. The iconic image of a digger with especially widened tracks working on a remote moorland is likely to be doing just that by creating dams to block grips and gullies.  

Our upland ombrotrophic, or rain-fed, peatlands, are among the UK’s most valuable ecosystems and a globally confined peatland type. These vast landscapes store carbon, regulate water, and support unique biodiversity, but despite their importance, a one-size-fits-all approach has often been applied to restoration and assessment.

The Eco-hydrological Guidelines for Peatlands introduces a more nuanced, science-led framework for understanding ombrotrophic peatlands. One that links vegetation, hydrology, and landscape structure. The result is a practical toolkit for identifying different, often hydrologically connected, bog types, assessing their condition, and planning effective restoration.

Why Peatlands Need Better Understanding

Peatlands are defined not just by their plants, but by the water table, peat depth and how water moves through them. Historically, conservation and restoration efforts have focused on visible features, such as vegetation or erosion, without fully understanding the hydrological processes underneath.

This project recognises that not all bogs function the same way, even if they appear similar on the surface. Differences in slope, peat depth, drainage, and water flow all shape the ecology of a site. These distinctions matter hugely when it comes to restoration, and future resilience.

Instead of broad classifications, the guidelines aim to provide clear, field-based methods to classify the range of habitats and topographical conditions associated with the vegetation types and peat surfaces found in blanket peatland landscapes in England and Wales and ultimately all UK nations. The guidelines will help in supporting decisions such as where to focus Sphagnum introduction and which species of Sphagnum, or understanding the importance and hydrological connectivity of the hill slopes on a system.

Fens, reedbeds and other lowland peat wetlands are covered in the existing 2009 predominantly England and Wales focussed Wetland Framework: A wetland framework for impact assessment at statutory sites in England and Wales - GOV.UK 

From Fieldwork to a Framework

The need for Eco-hydrological Guidelines for Peatlands was identified in 2018 by the Wetland Task Team associated with the Water Framework Directive (UKTAG). Phased funding has seen several years of work focusing on England and Wales. The publication of the Guidelines for England and Wales represents a significant step forward, but the ambition remains for this approach to cover all UK nations. 

To build this system, Sheffield Wetland Ecologists carried out extensive surveys across England and Wales covering:

• 62 field sites
• 472 habitat samples
• Measurements including peat depth, slope, pH, wetness, and vegetation composition

Field survey methods have been developed based on practicality and the need to cover large areas relatively quickly:

• LiDAR and aerial imagery used to plan surveys
• Samples recorded along transects
• No specialist equipment needed
• Rapid – each sample takes c. 30 minutes

Statistical techniques, including multivariate analysis, were used to understand patterns linking vegetation types with hydrological and physical conditions. The result is a robust, data-driven system that reflects real ecological variation. This has resulted in two complementary classification systems:

1. Bog Configuration Categories (BOGCATs) - The Shape of the Bog

These describe the physical form of peatlands, how peat sits in the landscape. There are 3 groups of BOGCATs:

• Hill Bogs – peat that follows the natural slope and contours of upland terrain
• Trough Bogs and Sump Bogs – flatter systems in valleys or basins, often with gentle drainage
• Mounded Bogs – peat that does not follow the shape of the underlying ground that builds up into domes (like raised bogs)

These categories help explain why water behaves the way it does in different locations.

2. Wetland Water Supply Mechanisms (WETMECs) – The Surface conditions of the Bog

These focus on hydrology - how water enters, moves through, and leaves a peatland. There are 7 new WETMECs: 

Hill Peat Slopes, Slackenings / Crests, Ombrotrophic Bottoms, Ombrotrophic Flows, Crowns, Aprons and Water Flow Tracks.

Examples include:

Hill Peat Slope

Sloping surfaces on Hill Bogs (the most extensive type of ‘blanket bog’).

Physical features: Slopes, gentle to steep.  Water level sub-surface, in dry conditions water cannot usually be squeezed out of the peat. Surface generally firm. Peat depth moderate to deep. Microtopography usually very subdued with only scattered patches of Sphagnum, low tussocks of cottongrass and deergrass. In some areas high hummocks of heather and Sphagnum capillifolium are distinctive. Pools are absent, except in erosion areas.

Vegetation: M19, replaced by M17 in western areas. Sphagnum (usually S. capillifolium) can be abundant beneath the sward. Feather mosses are usually abundant.

Ombrotrophic bottom

Un-mounded peatland infill of topographic trough. 

Physical features: Slopes flat to very gentle, water level: near surface, can easily be squeezed out. Surface firm with some softer hollows. Peat usually deep. Microtopography generally quite subdued but some Sphagnum hummocks and hollows amongst vascular plants. 

Vegetation: The firm peat surfaces of Bottoms support a range of vegetation types including vegetation dominated by heather and cottongrasses, often with abundant Sphagnum capillifolium and S. papillosum below the canopy (M18, M18/M19, M19). Some areas support quite tussocky vegetation with abundant Molinia.

Crowns

The wettest water shedding areas typically found at the top of mounded bogs (in the centre of ‘raised bogs’). 

Physical features: More or less flat. Very wet, water readily oozes from footprints or forms pools. Peat mounded, usually very deep. Surface soft to very soft and can be quaking, either a spongy layer of Sphagnum forming intimate hummock-hollow-pool complex or mosaic of firmer areas with softer hollows and pools, sometimes interconnected. Tussocks only scattered.

Vegetation: Sphagnum-rich forms of NVC communities M17 and M18 where the vegetation is an intimate mosaic of low hummocks and hollows with aquatic Sphagnum (S. cuspidatum / S. denticulatum). Hummock-hollow microtopography is particularly distinctive in M18 where there is a more or less continuous layer of spongy Sphagnum (usually dominated by Sphagnum papillosum). M17 tends to be less hummocky with ‘flats’ interspersed with elongated hollows. Larger pools and soakways (M1 and M2) often embedded. Drained or disturbed areas support M18/M19 and M17 typical of drier and firmer surfaces.

While BOGCATs describe structure, WETMECs describe function. Crucially, any WETMEC can occur within different BOGCATs, but patterns emerge in how they are distributed across landscapes.

Why This Matters for Restoration

The ultimate goal of this work is not just classification, it’s better outcomes for peatland restoration.

By using BOGCATs and WETMECs together, practitioners can:

• Map peatland structure and function
• Identify and describe intact areas of ombrotrophic peatland habitat
• Understand the hydrological connectivity of the surrounding landscape
• Predict how water will move after restoration
• Tailor interventions (e.g. blocking drains, rewetting) to site conditions
• Better understand what the restoration end point may be

For Natural England and Natural Resources Wales it could inform future designations too. This is especially important as all UK nations have ambitious restoration targets to meet as well as informing initiatives such as the Defra Peatland Standards for England and Wales which is currently being developed.

Looking Ahead

This work represents a significant step forward; it aligns with existing frameworks, while extending them into upland environments that have been poorly covered until now.

Future work will extend the approach across the UK, with funding secured to test the BOGCATs and WETMECs in Scotland in 2026.

With thanks to UKTAG, Natural Resources Wales and Defra for funding, the UKTAG Wetland Task Team members, land managers for access permission and everyone who assisted with fieldwork, data and feedback during the project.