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Application of surface motion remote sensing to quantify the condition and trajectory of change of c.680,000 ha of peatland

Large, David J.; Bradley, Andrew V.; Mitchell, Emily; Fallaize, Chris; Dryden, Ian; Andersen, Roxane; Marshall, Chris

Authors

Emily Mitchell

IAN DRYDEN IAN.DRYDEN@NOTTINGHAM.AC.UK
Professor of Statistics

Roxane Andersen

Chris Marshall



Abstract

The purpose of this report is to demonstrate and evaluate the use of peatland surface motion, as measured by interferometric synthetic aperture radar (InSAR) over eight consecutive years, and to quantify and report peatland condition and trajectory of change over large areas.

Peatland surface motion is a sensitive indicator of peatland condition and resilience (Howie and Hebda, 2018; Waddington, 2010; Loisel and Gallego-Sala, 2022). It is a mechanical response to changes in water storage that is determined by a range of peatland properties including elasticity (softness/stiffness), water table depth, plant functional type, land use history and topography. It provides a measure of the ability of a peatland surface to rise and fall with the water table (sometimes called ‘bog breathing’) and hence minimise the risk posed by drought and fire. It also gives an indication of the relative ease with which an area of peat will store water and hence the ease with which it may be restored.

This method provides measures of condition based on ground motion that results from the combined effects of ecology, hydrology and mechanics. This view of condition is a different use of the term ‘condition’ to that provided solely by ecological or hydrological measures. It is a view that provides new information about the behaviour of the peatland that enhances our understanding of peatland function and is complementary to ecological and hydrological measures of condition. Importantly it does not replace detailed assessment of peatland ecology or hydrology condition should specific measures of these parameters be required.

A significant advantage of the InSAR technique is the capability to monitor peatland surfaces irrespective of cloud cover, which can be a severe limitation for optical remote sensing methods in Scotland. This advantage permits frequent monitoring of surface location in order to create a time series of surface movement and offers the potential to monitor peatlands objectively at the national scale and over long time periods.

Previous work both in peer-reviewed publications (Alshammari et al., 2018; Alshammari et al., 2020; Bradley et al., 2022; Islam et al., 2022; Marshall et al., 2022) and NatureScot Research Reports (Bradley et al., 2025.; Large et al., 2025; Marshall et al., 2021), demonstrated that measures of peatland condition can be derived from surface motion over areas of 10s to 100s of km2 at 20 m resolution. The most recent method for achieving this uses satellite radar data processed using an interferometric synthetic aperture radar (InSAR) technique in conjunction with time series analysis and statistical machine learning (Mitchell et al., 2024). These methods were developed over a wide range of peatland conditions and geographic settings by sampling the blanket bogs and lowland raised bogs in the Flow Country, Aberdeenshire, Midland Valley of Scotland, and Dumfries and Galloway.

The technique has also been developed to quantify short- and long-term trajectories of change in peatland condition (Mitchell et al., 2025) that are sensitive to the impact of restoration, infrastructure development and drought.

The methods have been developed via funding from NERC (NE/P014100/1; NE/T010118/1; NE/T006528/1), Leverhulme Research Leadership Award (RL-2019-002), NatureScot Peatland ACTION and Forestry and Land Scotland. Much of this research has been supported by RSPB, Plantlife, as well as individual landowners, Highland Rewilding (Bunloit Estate) and Welbeck Estate.

The methods have now reached a point of maturity where they can be automated for large-area deployment, integrated with other datasets (e.g. high-resolution optical imagery, topography) and subjected to large-scale testing against a broad spectrum of known conditions. However, large-area deployment has its own challenges including maintaining the consistency of classified outputs over large areas involving multiple packages of InSAR data, each with its own frame of reference. There is also the question as to whether the current classification reliably extends beyond the settings currently investigated (e.g. to wetter areas or those with greater topographic relief).

Evaluation of the extent to which this method represents a practical solution to peatland monitoring therefore requires results to be generated over a large area. This report presents and evaluates the results of condition mapping and change detection at a large scale. Interpretation of the results is illustrated using twelve case studies.

Citation

Large, D. J., Bradley, A. V., Mitchell, E., Fallaize, C., Dryden, I., Andersen, R., & Marshall, C. (2025). Application of surface motion remote sensing to quantify the condition and trajectory of change of c.680,000 ha of peatland. NatureScot

Report Type Research Report
Online Publication Date Jun 13, 2025
Publication Date Jun 13, 2025
Deposit Date Jul 17, 2025
Series Title NatureScot Research Report
Series Number 1356
Keywords bog breathing; surface motion; InSAR; peatland condition; monitoring; change detection; probability
Public URL https://nottingham-repository.worktribe.com/output/51620188
Publisher URL https://www.nature.scot/doc/naturescot-research-report-1356-application-surface-motion-remote-sensing-quantify-condition-and