Ireland has comparatively little dense forestry left after millennia of settlement, agricultural expansion and the deforestation that came with it [1].
In their place, hedgerows have become one of the country’s defining landscape features, and one of its largest carbon sinks. An estimated 689,000 km of hedgerow criss–cross the country [2].
The following blog and maps have been created by Mallon colleague Dara McGovern.
Why Hedgerows Matter
Hedgerows are a lifeline for Irish wildlife, providing habitat for mammals such as hedgehogs, foxes, stoats, and pine martens, as well as for nesting birds, bees, butterflies, and moths [3].
They do practical work for farmers too. Hedges mark field boundaries and act as a natural barrier that helps slow the spread of livestock and crop diseases, including bovine tuberculosis and airborne crop pathogens [4].
Figure 1: Biodiversity of hedges (The Secret Life of Hedges – Teagasc | Agriculture and Food Development Authority)
Monitoring Hedgerows from Space
Hedgerows can be mapped and tracked using satellite and aerial imagery. Vegetation indices such as NDVI (Normalised Difference Vegetation Index) and EVI (Enhanced Vegetation Index) allow hedge lines to be delineated from imagery, and once a baseline is established, later acquisitions can be compared against it to flag change. This makes it possible to detect biomass–removing activity, such as hedge clearance or heavy coppicing, from orbit.
Satellite data is usually the more practical option, largely for cost and revisit frequency. Sentinel–2, part of ESA’s Copernicus programme, is a multispectral satellite constellation that can image the same location in Ireland as often as every five days, cloud cover permitting [5]. Aerial imagery offers finer spatial detail but is captured far less often and at greater cost.
Case Study: Detecting Hedge Removal with Sentinel–2
This example focuses on an area north of Drogheda, County Louth. Creating baseline of the area of interest using Sentinel–2 could be done with Machine Learning or Deep learning algorithms, for the sake of this small example, the hedge lines were digitised against Sentinel–2 data manually.
Figure 2: 2024 Sentinel–2 image with manually digitised hedge lines.
To detect where hedges had been removed, EVI values from 2024 were subtracted from EVI values in 2025, producing a difference map that highlights areas of biomass loss.
Figure 3: EVI difference map, 2024–2025.
The areas showing the largest change were then extracted and used to clip a buffer around the known hedge lines.
Figure 4: EVI change polygons with hedge buffers.
Filtering out smaller, likely spurious features isolated the largest patches of biomass loss — areas that correspond to the footprint of hedges that had actually been removed.
Figure 5: Areas of possible hedge removal against a 2025 Sentinel–2 image (hedge buffers clipped by areas of change).
This analysis was carried out using QGIS and Google Earth Engine.
Key Takeaways
Freely available satellite data, like Sentinel–2, can effectively monitor the presence and removal of hedgerows, helping protect a habitat that plays an outsized role in Ireland’s biodiversity and carbon storage.
Further Information
For further information about the methods used to produce the study and images above, or to discuss your Earth Observation requirements, contact us below.
References
[1] https://teagasc.ie/crops/forestry/advice/general-topics/history-of-forestry-in-ireland/
[2] https://teagasc.ie/news--events/daily-archive/mapping-irish-hedgerows/
[3] https://teagasc.ie/news--events/daily/the-secret-life-of-hedges/
[4] https://teagasc.ie/environment/biodiversity-countryside/farmland-habitats/value-of-hedgerows/
[5] https://sentinels.copernicus.eu/web/success-stories/-/sentinel-2-images-the-globe-every-5-days
