I was on a round the world trip (of sorts) last week, when the idea for this blog came to me – the global distribution of peatlands.

You could be forgiven for thinking that peatlands are confined to places that look similar or at least have as much rain as our own small portion of northwestern Europe, where peat of varying types dominates considerable swathes of our landscape. The surprising reality is that peat can be found in 175 of the world’s 196* countries ^[1]. From the frigid polar regions to the humid tropics, unless you’re standing in the middle of a desert, you probably aren’t too far from a peatland of some sort!

The global distribution of peatlands [2]

Sifting through the statistics on global peatland distribution has also turned up a number of unexpected numbers. For example, would you be surprised to learn that Malaysia has nearly as much peat (c. 26,685 km²) as Norway (c. 29,685 km²)? Furthermore, Sudan has 29,910 km² worth of peatland – that’s more than the United Kingdom (c. 17,113 km²) and Ireland (c. 11,090 km²) put together ^[3]!

It is perhaps less surprising that Russia is covered in peat, but the statistics are still astounding – the country has 1,375,690 km² of peat ^[3]. To put that in context, if that area of peatland was a country in its own right, it would be the 20^th largest sovereign state on earth. Alternatively, using another international measure of land surface area – it’s over 66 times the size of Wales!

So, back to my ‘round the world trip’. Admittedly, I didn’t get to actually leave the lab, but the space of just a few days, I had worked on peat samples from 4 different continents – from Arctic Sweden to the Antarctic Peninsula and from southern Patagonia to tropical Borneo. As a Bogologist, it was pretty exciting!

A thermokarst pool in a palsa mire, Arctic Sweden [photo: Graeme Swindles)

A typical tropical swamp forest peatland in Indonesia [photo: Jenny Farmer]

Moss growing on steep, snow free cliffs on Green Island, Antarctica [photo: J Royles]

Pool, lawn and hummock landforms in Patagonia.

A clue to this broad global distribution of peat is revealed when we consider the definition of the term peatlands. The IUCN Peatland Programme’s Commission of Inquiry on Peatlands suggests that peatlands are:

The oxygen-free conditions provided by this waterlogging generally prevent plant material from decaying fully and so it accumulates over time forming peatlands. So, whilst there are many contributing factors in their initiation and development, in the majority of instances there are two key ingredients for peat formation: water and plants.

The vast majority of peatlands are located in the northern hemisphere’s boreal regions where low temperatures and high rainfall mean that evapotranspiration rates are generally low and so there’s plenty of water around to ‘fuel’ the regions peatlands. However, as our samples from Borneo demonstrate, peat isn’t confined to cold places and can accumulate in a range of humid environments, provided that ‘effective precipitation’, a trade off between rainfall and evaporation, is high enough.

With regard to the plants, it’s important to note that whilst many peatlands are dominated by the ubiquitous Sphagnum mosses and a predictable suite of soggy sidekicks (e.g. sedges, rushes, heathers), this isn’t always the case. Again, the peatlands of Borneo occur in forests where fallen leaves and woody debris are prevented from complete decay by an excess of water, thus forming a layer of peat on the forest ‘floor’. At the other end of the climate spectrum are the moss banks of Antarctica, which we’ve talked about in previous blogs. These are often dominated by no more than two species of (non-Sphagnum) moss – and that’s it!

Research into the potential of these more unusual peatlands for the reconstruction of past climate change is increasingly rapidly. We’ve already blogged about the evidence for rapid warming in the Antarctica Peninsula found in the moss banks and just last week a brand new paper, led up by Dr Graeme Swindles at the University of Leeds, demonstrated the potential of testate amoebae found in the tropical peatlands of the Amazon for reconstructing past hydrological changes was released.

As our ‘traditional’ techniques are applied in new and increasingly more exotic contexts, it certainly is an exciting time to be a Bogologist!

*Quite how many countries there are in the world is a matter open to debate. Luckily its one that doesn’t really affect the statistic here!

^[1] IUCN Peatland Programme’s Commission of Inquiry on Peatlands

^[2] Peatlands for climate and biodiversity, Wetlands International 

^[3] The Global Peatland CO2 Picture, Wetlands International.