Site trials conducted by Historic Environment Scotland into the impact of marram harvesting on the Western Isles are taking place in Berneray this month.

Marram grass is a coastal grass which is used as a roofing material for thatched structures in Scotland and parts of Ireland.

Historic Environment Scotland (HES), alongside NatureScot, will be carrying out the site trials as part of ongoing research into this material.

Marram grass has been harvested for thatch in the Western Isles for centuries. However, it also plays a key role in the ecosystem as vegetation and is important for the dune systems along the coastline. These dune systems protect the coastline, habitats, agriculture, human settlements and infrastructure across the isles.

There is currently no scientific evidence which shows the impact of cutting marram grass on these dune systems and their role in coastal protection.

This site trial, which will take place over roughly five days, is the first of several which will be happening over the next four years. The trials will help answer the question of how sustainable marram harvesting is and how cutting marram affects plant growth, dune stability and rate of coastal erosion.

The knowledge gaps around marram grass were identified in the Western Isles Thatch Audit which is due to be published next month.

HES and NatureScot hope that the results of this research will give a better understanding of best practice in harvesting marram grass and support updated recommendations for managing areas of this coastal grass.

Ali Davey, Project Manager for Traditional Materials at HES, said: “Conducting these site trials will give us important information about marram grass and whether using it for thatching is sustainable for the wider ecosystem. Keeping traditional skills and materials in use, such as thatching, is very important to us, but it is vital that we do this in a sustainable, responsible way.

“We would like to thank the community at Berneray for their patience while we conduct this work, and we are excited to share our findings in due course.”

Johanne Ferguson, NatureScot’s Operations Manager for the Outer Hebrides, said: “Our dune systems are among Scotland’s most valuable habitats and provide natural coastal defence. They are at threat from a variety of pressures including sea level rise, coastal erosion and development. This research will help to fill a knowledge gap in our understanding of the impact of marram grass harvesting on dune systems.

"The trials are carefully planned in a location where the dunes are unusually robust and growing well, so what we learn here can be applied to other locations where changes to dunes are more likely to create risks to coastal assets, such as homes, crofts, and roads.”