World Wetlands Day: An introduction to peatland
“If your feet are wet but you can’t swim, then its peatland”
For this year’s World Wetlands Day, we decided to dedicate our blog to a very particular kind of wetland, peatland. We invited the President, one of the two Vice-Presidents, and Acting Secretary General of the International Peatland Society (IPS); Marko Pomerants, Jack Rieley and Susann Warnecke respectfully, to give us an introduction to peatland.
What is the difference between wetlands and peatlands?
Peatlands are wetlands but not all wetlands are peatlands. A wetland is an ecosystem which is either permanently or temporarily flooded or full of water. This includes everything from bogs, swamps, coastal shallows and more, but there is a distinction between freshwater wetlands and saltwater wetlands.
How do you define peatland?
Peatland is a type of freshwater wetland with an accumulation of partly decomposed plant matter. Specifically, the water, acidity levels, lack of oxygen and the incomplete decomposition of organic materials leads to accumulation of organic matter over time which is later referred to as peat once it reaches an approximate 10-20cm level of thickness. It is important to note that this is a broad description as there is no fixed definition as peatlands and peat can develop in every continent in the world and from different plants in different locations. Colloquially though, you can say if your feet are wet, but you can’t swim then you’re in a peatland.
Where does peatland form?
In short, on every continent, 50% of wetlands are peatlands. 12% of global peatlands are tropical peat swamp forests, commonly known as rainforests in the tropics. The remaining 88% of peatlands are non-tropical with the majority situated in the Northern hemisphere as we do not have as much land mass in the Southern hemisphere. Where they form, even regionally, can vary. In Scotland you have blanket bogs which are formed way up on mountain ridges, whereas in Finland you see them forming in shallow areas, in former lakes as well as land that is still being lifted after the last ice age, while in Siberia they are often affected by permafrost. Due to the wide range of causes, the ages of peatlands throughout the world can vary from a few hundred to tens of thousands of years.
What are the variations of peatlands and what does this mean for the peat?
In Northern Europe, the bog moss Sphagnum is the main peat forming plant, but depending where you are on earth peat can be formed by completely different plants, for example in the tropics in Southeast Asia the main peat formers are rainforest trees that can be more than 30 meters tall. All over the world, peatlands are natural ecosystems populated by a myriad of different plants ranging from primitive low-growing mosses to massive trees. This leads to peat with varying biological, chemical and physical characteristics of incredible complexity. In the tropics peat has a very high wood content, including branches and trunks making its qualities different from Sphagnum peat and difficult to extract to use for energy or growing media.
Talking of growing media, which peat has the best characteristics for growing?
When it comes to growing media used by gardeners or commercial growers of food and ornamental plants there is a difference between fen peat which comes from lowland peatland, that received nutrient-rich ground water in addition to rain, and raised bog peat, which forms in waterlogged, acidic, nutrient-poor conditions at the end of mire succession from open water wetland when the area is fed only by rainwater. Only special mire plants can survive in acid peat bogs. Fen peats contain an abundance of sedges, grasses, and other emergent plants such as bulrushes collectively referred to as reeds together with a large variety of other flowering plants. Fen peat can provide a nutrient-rich ingredient that can be used for some types of growing media. Most of the peat used in horticulture growing media is harvested in the northern hemisphere (especially Europe and North America) from raised bogs, they are fed by rainwater only and that have an abundance of Sphagnum mosses. Peat is an important ingredient for growing media on account of its availability, quality, reliability, and lack of disease or pest vectors that provides a more neutral or “clean” substrate which is high in demand as it can be used to support the growth of almost all plants.
Why are peatlands important?
The importance of peatland can be divided into three sections: Environmental, social, and economical.
Environmentally, peatland is obviously the home to a large variety of flora and fauna throughout the world. Peatlands although they cover only 3% of the global land surface are one of the largest stores of carbon extracted as carbon dioxide from the atmosphere by the peat-forming plants. It is said that peatlands store more carbon in their peat than all the world forest above ground biomass. However, because peat is around 90 per cent water peatland plays a key role in the water cycle by detaining, storing, and releasing rainwater it makes it also important for human communities.
Socially, peatlands have a long history with humans. There are folktales that they are home to fairies and trolls, they are sites for artefacts as people hid their possessions, and they were used as shelter during difficult times such as war and famine. They were sources of food and material for shelter. These days they offer people a place to walk, to be outside, to collect berries and mushrooms, and enjoy the fresh air.
Economically speaking, peat has been harvested for not just hundreds but thousands of years. The peat was used for insulation of houses, until recently it was burnt for heating, and of course animal bedding. The peak of harvesting came in the late 18th and early 19th century due to the reliance on animals and the need for bedding. During the World War I, there were so many horses they had to dig peat bogs almost out of existence, for instance in the Netherlands. In the modern-day world very little is extracted. There are 4 million km2 of peatlands in the world and we harvest just 4000km2, of which only half of that is used for horticultural purposes. Burning peat for energy has almost completely ceased due to high emission right costs.
Today the activity happening to peatlands is restoration and rewetting. This is happening across the globe on near pristine as well as former industrial sites, afforested sites, in tropical peat swamps and even urban areas.
What are the biggest challenge peatlands face today?
In developed countries peatland drainage and degradation has taken place over centuries mainly for agriculture – arable crops and livestock bedding and grazing, but also for domestic purposes, burning and water supply. The priority is to rehabilitate degraded peatlands back to their original peat forming, carbon storing condition. This is a major challenge that has already started in many countries, but it involves dam construction, rewetting, re-vegetating (with Sphagnum) and is costly.
In undeveloped and developing countries where the importance of peatlands as carbon stores is just being realised and, hitherto, unknown peatlands are being discovered the challenge is to persuade governments not to embark on wholesale development for agriculture or plantations of traded commodity. This will only create similar problems found in the developed world of peat oxidation (decomposition), subsidence, flooding and eventual loss of economy and livelihoods.
If peatlands and peat must be used this must be done in a responsible manner with after use plans in place and parallel restoration of previously degraded peatland as offset.
Endnote
There is an odd myth that extraction of peat is the biggest threat to peatlands but that isn’t true. It is mainly agriculture, forestry and climate change which are destroying the ecosystems of many peatlands. Globally, greenhouse gas emissions from drained peatlands accounts for around 5% of global emissions. Statements usually say this comes from agriculture, forestry and peat extraction, implying that these contribute equally. In fact, agriculture on peatland soils contributes 75% (of the 5%), Forestry about 25% (of the 5%) while peat extraction contributes less than 0.1% (of the 5%). This puts the matter in perspective.
About IPS
The International Peatland Society is the only international organisation that is dedicated to every aspect of peatlands, including peat industry. Its more than 1600 members are mostly scientists and other experts, but it also has around 300 corporate company members. IPS aims to be the leading international organisation promoting the responsible management and wise use of peatlands and peat with the mission to serve all those involved in peatlands and peat through the promotion, gathering, exchange and communication of knowledge and experience, by means of events and projects which address key issues, including climate change, biodiversity, the need for responsible use and restoration. Learn more here.
About Marko Pomerants
Marko Pomerants is a qualified Geological Engineer who has worked in multiple positions within the Estonian government including Minister for Environment a role in which he signed the Paris climate agreement on behalf of Estonia. He is the President of IPS.
About Jack Rieley
Professor Jack Rieley is a semi-retired academic who specialises in botany, peatland ecology and nature management. He has been a member of IPS since early in its formation and is one of two Vice-Presidents of the organisation.
About Susann Warnecke
With a background in Business Administration Susann Warnecke has been with IPS for over two decades and is currently their Acting General Secretary.