Sphagnum is a flowerless genus of moss with some quite remarkable properties.
There are 125 moss species in the Sphagnum genus.
Different species of Sphagnum moss often form low lying living ‘carpets’….
…and thrive in boggy, damp conditions.
Sphagnum moss also flourishes on damp forest floors…
…and even at the bottom of volcanic craters.
The reproductive spores of Sphagnum moss develop inside capsules. These capsules rise on stalks above the leaves.
Each capsule contains up to 30,000 microscopic spores.
The capsules containing the spores are sometimes different in shape.
In the summer months the spherical capsules start to dry out. As they dry out the capsules dehydrate….
… and shrink. They then become compressed which leads to a build up in air pressure.
Eventually the internal air pressure becomes so great that the lid of the capsule blows open. The spores escape from inside the capsule and rapidly accelerate upwards and outwards.
The whole sequence is summarized below:
The escaping spores, accelerating incredibly fast, then form a mushroom shaped cloud.
The formation of a mushroom shaped cloud is recorded in this sequence of images below. Each image represents 1/10,000th of a second. The whole process, from explosion to formation of mushroom shaped cloud, takes only 9/10,000th of a second!
The spores accelerate with a gravitational force (G-force) of 36,000 g!
By way of comparison the maximum rate of acceleration of a Bugatti Veyron is 1.55g…
…the rate of acceleration of an ejector seat is 15 g ….
….while the rate of acceleration of a 9mm bullet fired from a handgun is ‘only’ 31,000 g.
Even Superman doesn’t accelerate as fast as Sphagnum moss spores!
The rapid acceleration of the spores has been captured in this slow motion video:
Exploding out of their capsules allow the spores to escape the windless zones near ground level and reach the faster more turbulent airflows located 10 centimeters above the ground.
These turbulent airflows help disperse millions of microscopic spores to new habitats often many kilometers away.
If the spores land somewhere where they can grow they will germinate and produce the next generation of plants.
The circulation of spores in mushroom shaped vortex rings enables the spores to stay in the air longer and travel further.
This very successful method of reproduction has led to the formation of vast Sphagnum peatlands throughout the world.
As old plants die new plants grow on top. Slow rotting, dead plant material accumulates under this new growth.
This accumulation of dead plant material produces a type of soil called peat. Over time the peat soil becomes deeper and deeper until peatlands are formed.
A thick layer of peat soil can be seen in this image where it has been excavated.
On average, peatlands increase in depth by one centimeter every 10 years. So that makes this peatland over 1000 years old!
The accumulation of peat soil is greatest in areas where temperatures are high enough for plant growth but low enough to slow down the rate at which plant matter decays. There also needs to be high rainfall and ….
….low levels of evapo transpiration.
Such conditions, ideal for the growth of Sphagnum peatlands, are found in vast regions of North America, northern Europe and Russia.
In these northern regions Sphagnum moss is the foremost peat forming species.
Individual Sphagnum moss plants can store large quantities of water inside leaves, branches and stems.
The cumulative effect is that millions of individual Sphagnum plants, both dead and alive, contribute to an eco-system that remains permanently waterlogged.
In such waterlogged conditions subsurface layers of peat soils are deprived of oxygen. This lack of oxygen slows down the rate of decomposition of dead Sphagnum found below the surface.
These unique soil conditions (very acidic and lacking in oxygen) mean that anything dropped in peatlands often remains very well preserved.
Many ancient artefacts have been found in peatlands including this wooden wheel; it was found in Holland and has been dated at around 2700 BC making it more than 4,700 years old!
Sphagnum moss removes vital plant nutrients, such as potassium and magnesium, from the soil. This makes it impossible for many plant species to grow.
Those plant and animal species that can survive in Sphagnum peatlands have had to adapt to living in conditions in which there are few nutrients.
The Common Sundew (Drosera rotundifolia) is one plant that can survive in Sphagnum peatlands. It extracts all the nutrients it needs from the bodies of insects that it captures.
Using a glue- like substance this Common Sundew has captured a yellow and brown colored butterfly.
Wildlife commonly found in Sphagnum peatlands includes red grouse of Scotland….
…dragonflies of northern China….
…and Corroboree frogs of Australia.
The two main processes by which Sphagnum peatlands develop are called terrestrialization and paludification.
This is the process by which peatlands grow over water.
In the initial stages Sphagnum moss grows near the shore of a lake or pond as a floating bog mat.
This floating bog mat of Sphagnum moss also contains sedge grasses and Sundew carnivorous plants.
Over time peat soil in the floating bog mat starts to infill the lake. The lake slowly becomes smaller….
….until the lake completely silts up. This peatland in Slovenia has developed out of several silted up lakes.
a) Blanket bogs
These can be found in cooler climates in which rainfall is consistently high. The surface of the land remains waterlogged, providing ideal conditions for the growth of Sphagnum moss.
In such circumstances peat soils “blanket” much of the land, including hilltops and slopes.
Blanket bogs can also be found in mountainous regions. This blanket bog is in northern Spain.
b) Raised Peat Bog
Some peat bogs, such as this one in Scotland, are raised above the level of the surrounding countryside.
Before a raised peat bog can be formed, colonised by Sphagnum Moss, a process of terrestrialization needs to take place.
Following the retreat of the last ice age in Europe 10,000 years ago…
…lakes formed in the shallow depressions that were left by the retreating ice. Trees and plants grew beside these lakes and aquatic plants grew on the surface of the lakes.
Over time dead plant material infilled the lake. The plant material sitting at the bottom of the lake formed a thick layer of peat soil that, over time, grew upwards towards the surface.
These peat soils, unlike the more acidic Sphagnum peat soils, were either alkaline or only mildly acidic.
Conditions were not yet acidic enough for Sphagnum moss to grow.
Eventually these peat soils infilled the lake until it completely disappeared. The peat soils were fed by mineral rich groundwater and surface water forming what is known as a fen.
The mineral rich water feeding the fen ensured that the peat soils remained alkaline or only mildly acidic.
As the fen peat thickened, the roots of plants growing on the surface could no longer feed off any mineral-rich groundwater.
The only source of minerals for plants was now rainwater, which contains few minerals. Such conditions favored the growth of Sphagnum moss which soon turned the soil acidic.
The more Sphagnum moss that grew, the more acidic the soil became.
You can view the whole process, from lake to raised peat bog, in this video.
Sphagnum peatlands capture and store vast amounts of atmospheric carbon dioxide. This helps prevent the accumulation of greenhouse gases in the atmosphere and helps slow down the rate of global warming.
Consider this amazing statistic: 3% of the earth’s land surface is covered by peatlands but peatlands have captured 33% of all the carbon in all the soils of the world.
Peatlands lock away VAST amounts of carbon.
This carbon storage is threatened by human activity….
Photo courtesy of Killofin Home Genuine Irish Peat
….which sometimes takes place on an industrial scale.
Peat has traditionally been used for cooking and heating for thousands of years. Burning peat releases stored carbon back into the atmosphere as carbon dioxide gas.
Peat is also widely used in agriculture and gardening. When mixed with soil, peat helps improve mineral and water retention.
Information about Irish peat in Natures way- the Wonder of Peatlands
Some great water color paintings illustrating the different stages of Raised Bog development.