Our recent publication, 50 for the Future, lists 50 things that we believe should happen in Scotland over the next 50 years to benefit both people and wildlife. In this week's 50 for the Future article, Dr Scott Shanks, a Conservation Officer for Buglife Scotland, provides insight into why it is so important to protect and restore Scotland's lowland raised bogs.
Number 13: Ensure every lowland raised bog in Scotland supports a rich variety of peatland wildlife
The loss of lowland raised bog habitat
Raised bogs are distinctive wetland habitats that have formed over thousands of years in rainy, acidic, nutrient-poor locations that favour the growth of Sphagnum mosses. These wonderful bryophytes are the foundation of bogs, and can absorb large volumes of rainwater. Many species can be found growing together in dense mossy carpets, or in acidic bog pools.
In these oxygen-poor, water-logged conditions, dead Sphagnum shoots and other vegetation only partially decompose and accumulate over time to form a characteristic dome of rainwater-saturated peat. An active, healthy bog can grow up to 1mm of peat per year. Some of Scotland’s deepest bogs have been accumulating peat for over 8,000 years!
Over 94% of our raised bogs have been lost in the last 200 years due to a combination of drainage for agriculture, afforestation and commercial peat extraction. The majority of remaining raised bogs have been damaged and left in poor condition.
The wildlife and plants that thrive on a healthy peatland are uniquely adapted to cope with the harsh conditions required for life on a bog. But drained and degraded bogs are often devoid of the characteristic flora and fauna and are a major source of greenhouse gas emissions.
Raised bogs support a diversity of species adapted to the unique conditions found there. Bog pools and mounds of Sphagnum create a varied micro-topography across the bog. In wetter areas, cotton grasses and sedges dominate, while in drier areas, seas of pink cross-leaved heath, heather and blaeberry shade sprawling cranberries and sundews. The insectivorous sundews thrive in the nutrient-poor conditions of bogs by producing sweet sticky ‘dew’ from their leaves to attract, capture and then digest small invertebrates.
Many invertebrates are associated with healthy raised bogs including the large heath butterfly and the bog sun-jumper spider. On sunny days hieroglyphic ladybirds hunt for heather beetle larvae to snack on, while the day-flying male emperor moths soar over the bog looking for mates. Bog pools are important habitats, packed with water beetles and the predatory larvae of black darter and common hawker dragonflies.
In spring and summer, many ground-nesting birds including hen harriers, curlew, skylark and meadow pipits breed on raised bogs. In winter, the wet ground and open views provide relatively safe roosting sites for many wildfowl. Common lizards and adders can often be found basking on mounds of Sphagnum, and frogs and palmate newts will breed in pools of Sphagnum and bog bean.
How can we ensure that every raised bog supports a rich variety of wildlife?
Many of the iconic species of raised bogs have been lost in recent decades. Remaining populations are often highly fragmented, which increases the threats of local extinction though natural disaster, disease or the loss of genetic diversity. The key to saving these species is to protect, restore and reconnect the bog habitat that they depend on.
- Protect – The cheapest solution is to protect existing intact bogs from the damage caused by drainage, afforestation and scrub encroachment, burning, trampling by livestock, nutrient addition, and above all from commercial peat extraction for horticulture – which is a very destructive process!
- Restore – The key to restoring damaged bogs is raising and stabilising ground water levels in the peat to encourage the recolonisation of Sphagnum. Key techniques are blocking drainage ditches with dams, and removing trees and invading scrub that can further dry out the bog.
- Reconnect – Expanding areas of high quality bog habitat and reconnecting networks of smaller bogs are key to the survival and recovery of threatened bog species.
It’s not only wildlife that benefit from protecting raised bogs…
Intact raised bogs act as enormous carbon sinks. However, if drained, huge amounts of CO2 and other greenhouse gases are released as thousands of years of partly-decomposed vegetation resumes the process of decay. Restoring damaged bogs prevents the release of further greenhouse gases and encourages the growth of peat-forming Sphagnum mosses which lock up even more carbon. It also contributes towards the Scottish Government's climate change targets.
Raised bogs can hold an enormous volume of rain water and can help to prevent local flooding by slowing the movement of rainwater into rivers following storms. Water leaving intact bogs tends to be of high quality, as atmospheric pollutants are filtered from rainwater. Conversely, drainage ditches and areas of bare peat left after peat extraction will speed the flow of rain water contaminated with suspended particulates and high in dissolved organic carbon (brown colour in peaty water) into rivers.
The special conditions that promote the formation of peat also preserve other organic materials. Undamaged bogs can hold thousands of years of archaeological treasure in the form of layered pollen and plant fragments, insect remains (and the odd sacrificial bog body!) which can provide a unique window into the climate, ecosystems and lives of our ancestors.
There really are plenty of reasons to protect our peatlands!
Let us know your thoughts by emailing firstname.lastname@example.org or Tweet @ScotWildlife using #50fortheFuture.
Dr Scott Shanks is a Conservation Officer for Buglife Scotland