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24 Jul 2020

Peat bogs: windows to the past – preserving the future

Written by Rob Dewar, Nature Conservation Advisor at the National Trust for Scotland
A peat bog landscape, with a large pool of water and mossy hummocks and reeds sticking out. Mountains can be seen in the distance.
International Bog Day is celebrated each year on the last weekend of July and promotes the vital role of peat bogs as an ecosystem – capturing and storing carbon, filtering and regulating water flows, and providing homes for rare wildlife.

International Bog Day was conceived in Scotland in the early 1990s as a way of engaging the public in the wonders of peatlands, which had up to that point been very undervalued. Scotland holds the majority of the UK’s peatlands and about 12% of the globally rare blanket bogs, found in our uplands. The National Trust for Scotland supports peatland conservation work through policy initiatives such as the IUCN UK Peatland Programme, awareness-raising events, provided by our ranger service, and also by land management restoration work on our upland properties.

This year, the coronavirus pandemic has curtailed our public engagement, so there has been little opportunity to show people the magical world of our peat bogs. Hopefully this description of our superb patterned bogs at Inverewe gives you a flavour of why our peat bogs are so special ...

A close-up of a dragonfly resting on a twig. Its four wings are held out to the side, and it has a fairly short black and yellow body, with a forked tail.
A four-spotted chaser dragonfly in the peatland

What do the Inverewe peat bogs look like?

The wilderness of Wester Ross and the Flow Country contains some wonderful pristine peat bogs, unaltered by man and steadily becoming ever deeper as time moves on. At some sites in this landscape the peat has been forming since soon after the ice retreated, which means peat depths of 8–10 metres.

We took a stroll over the moorland at Inverewe to the closest of the patterned bogs. The glistening pools appeared before us as we approached over a rocky outcrop. The bog habitat supports a specialised and wonderful array of wildlife – to demonstrate this, a pair of keeled skimmer dragonflies swept over the sphagnum-rich bog pools in a frantic flight. Bogs are not in a hurry, but these creatures were making the most of the sunshine.

Sphagnum moss forms the building blocks of peat formation. These splendid mosses range in colour, from yellow, green, orange, red and crimson. A mossy sphagnum hump can be a radiant patchwork of colour. It’s in a very wet bog that the plant really comes into its own as it can absorb twenty times its weight in water. And these bogs are still growing! As the sphagnum plant material decays, it forms peat at an average of 1mm every year.

A red-green plant has tentacles, reaching up into the air. It is growing on a bed of moss, covered by water.
Sundew growing on sphagnum moss

How do we know how old the peat is?

Five drain rods were improvised and fastened together to probe the depths. As we drove the rods down through the peat, we reflected on the world events as this peat bog was forming: the Highland Clearances, the building of Hadrian’s Wall, Stonehenge – you get the picture. The fifth rod eventually started to reach more solid ground, so we estimated the bog had begun forming around 5,000 years ago. We had reached the Neolithic period! This would fit with the scientific evidence that the climate became much wetter in Britain from around 4000BC.

There are a number of other clues to the age of peat bogs. I’ve gazed through the murky depths of water to fix my eyes on mysterious tree stumps embedded in the bottom of lochans. These are the remains of fossilised trees, traditionally called ‘bog fir’, and give an indication of a very different historical landscape. Pollen grains may be identified through a microscope to provide yet another window to the past, giving us a picture of the vegetation in the landscape thousands of years ago.

Our amazing peat bogs also harbour incredible human artefacts, such as ancient treasure troves of jewellery or swords cast into the bog thousands of years ago, perhaps as offerings to the gods? Another curiosity that has often been found by peat cutters is that of ‘bog butter’ in earthen pots. It may have been left in the bog to keep cool when supplies were not so plentiful. Peat bogs are anaerobic so they have a wonderful ability to preserve. The most incredible example of the bogs’ ability to preserve is the numerous ‘bog bodies’ that have been discovered all around the globe. Some of these souls have met a grisly end, with some bodies having rope still intact around the neck. We can only surmise at the reason for their demise.

What role do peat bogs play today?

The stories that the bogs reveal about the past are reason enough to celebrate, but bogs play an even more vital role today – one that is becoming ever more crucial as our climate begins to rapidly warm. The peat in the bog is locked-in carbon, in a similar way to forests, but over longer timescales. It will not be released unless the bogs are disturbed, and a healthy sphagnum-rich bog is still actively capturing carbon. Bogs are part of our planet’s skin. It is a very spongy skin, storing vast amounts of water that is filtered and released slowly into our river systems. At the same time, the carbon-storing peat helps to maintain the Earth’s temperature. The bad news is that 80% of the peatlands in the UK have been degraded by drainage, afforestation, burning and peat extraction. Given the implications and projected cost of climate change, continued damage to peatland must cease.

A peat bog landscape, with a large pool of water and mossy hummocks and reeds sticking out. Mountains can be seen in the distance.
The patterned peat bog landscape at Inverewe

What is the National Trust for Scotland doing to help?

We have made a conservative estimate of there being 160 million cubic metres of peat on our upland properties, which is a carbon store of 27.5 million tonnes. This equates to about a third of the annual greenhouse gas emissions in Scotland.

We are determined to protect the ecological function of the peat bog. We have evaluated the health of our peatland and have already undertaken restoration work on upland properties at Ben Lomond, Ben Lawers, Goatfell and Mar Lodge Estate. Working with other bodies such as Scottish Natural Heritage, we have restored the hydrology through blocking drains with peat dams, repaired the eroded peat with reprofiling and mulched bare areas of peat with heather brash. All of this work ultimately helps stop further erosion, locks in carbon, and restores the hydrology so the peat bog can function in its natural role in regulating the ecosystem – benefitting people and the unique wildlife that thrives in fully functioning bogland.

We value your support in helping us to protect one of the most important global habitats, one that plays such a vital role in the Scotland we cherish.

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