‘Biocrusts’ and ‘Blanket-bogs’

Moss can bio-engineer hospitable environments for other plants and animals. In this post I write about my urban explorations of mossy carpets growing in urban space, and the ancient blanket-bogs and peatlands in the Peak District National Park.

I have developed a permanently active ‘moss radar’. My favourite mosses to spot are still the most common species found in the urban environment. Much to my family’s irritation, I often stop to inspect random brick walls or tree trunks. Moss can survive in the most extreme environments. It can grow on surfaces devoid of soil baked dry in the sunlight and scoured by rainfall and wind. The moss somehow hangs on; it is resilient, and slowly persistent. 

As an ‘early coloniser’ moss can grow on bare soil or rock, helping to lock in moisture and bind the soil together. It can also help to form the growth substrate for other plants. A single spore slowly develops into a tuft and then a small clump, which can eventually conjoin with others to make a moss-carpet or ‘biocrust’ as is the more delightful scientific term. ‘Spreading earth moss’ (Physcomitrella patens) is known for its tolerance to drought and rapidly appearing on bare soil. It is widely studied by scientists, with the potential to be used as a tool to combat desertification[3]. Leptobryum pyriforme is a moss that grows on bare soil after forests fires. Some of the most fascinating urban moss sites I have visited are obscure abandoned car parks and buildings. I love how the moss envelops and subsumes and softens concrete blocks and jagged rock, or with enough time, almost any object that remains still for long enough. 

While many mosses are resilient and seem to thrive in the urban environment, some are very sensitive to pollution and are only found in more remote areas of the countryside. This panorama makes me think about what the air quality would have been like at the time. You can see the train carts arriving piled high with coal and the smoke-blowing chimneys rising into the skyline. In the distance, you can just make out the hills of the Peak District. During the industrial revolution, the hillsides of the Peaks District were stripped bare of plant life by acid rain. Sites such as ‘Bleaklow’ and ‘Blackhill’ (possibly named after the bare peat hillsides) were “downwind from some of the worst pollution the world has ever seen” [2]. Despite improvements in air quality these sites still need urgent need of protection. Pressures on peatlands from intensive land management, industrial pollution and wildfires have left them in a degraded and eroding state.

I met up with Hydrologist Adam Johnston who took me on a walk from Edale up to the peatlands or ‘Blanket-bogs’ on the Kinder plateau. This remote site takes several hours to walk to. After a steep climb, the terrain change as we walked into the blanket bog was clearly defined by the blacked edges of exposed peat and a distinct sponginess underfoot. There is a wide diversity of plants and grasses and mosses and animals, some unique to this environment. There is something about the bleakness and quietness of this landscape that I find strangely calming. 

Photograph of Sphagnum moss

These unique blanket bogs are home to specialist plants, such as Sphagnum moss which can hold 20 times its own weight in water. This kind of moss play a vital role in maintaining the wet conditions necessary to slowly create peat. 

It is estimated that these blanket bogs have been growing for up to 8000 years. Without the active ‘biocrust’, the mosses and other plants, the peat dries out. It reacts with the air, releasing the carbon dioxide trapped in the peat over thousands of years. The exposed peat is less able to retain water and is washed away by rainwater or blown away by the wind. This also contributes to flooding in the lowlands. 

Photograph of peatlands restoration work showing small dams ['Bunds'] in the gullies.

The peatlands restoration work involves installing small dams [‘Bunds’] in the gullies. They help to retain water and create damp conditions for sphagnum moss and other wetland plants to grow back. In this image, you can clearly see how plant life is growing back behind the dam.

To find out more about the restoration work or to get involved, visit: https://www.moorsforthefuture.org.uk/our-work/restoring-blanket-bog

This is one of a series of blogs written by Anthony Hall who is exploring the secret life of moss specimens in our natural history collection. Click here to see his other blog, Moss is not the Enemy.


[1] https://www.theguardian.com/science/2021/jun/19/robin-wall-kimmerer-gathering-moss-climate-crisis-interview?CMP=Share_AndroidApp_Other

[2] Polluted legacy: Repairing Britain’s damaged landscapes https://www.bbc.co.uk/news/uk-england-derbyshire-17315323

[3] Moss biocrusts buffer the negative effects of karst rocky desertification on soil properties and soil microbial richness: https://link.springer.com/article/10.1007/s11104-020-04602

Could you use Physcomitrella patens in the combat of desertification, a moss that is highly tolerant against drought? https://desertification.wordpress.com/2016/11/30/could-you-use-physcomitrella-patens-in-the-combat-of-desertification-a-moss-that-is-highly-tolerant-against-drought/

[5] Find a detailed downloadable PDF of the Oldham Diorama here