06 "Bog protection is climate protection"
"Bog protection is climate protection"
The starting screen: under the magnifying glass
The bog under the magnifying glass
In intact bogs the peat grows at a rate of 1 mm per year. Hence a 1 metre thick layer might be almost 100 years old.
Touch the piece of peat with the palm of your hand! Its colour and structure will tell you something about when it was created.
Sphagnum under the magnifying glass
Peat moss from the Sphagnum genus is responsible for the special qualities of the bog. The plants have no roots and feed off rain water. They can absorb a minimum concentration of nutrients that they take from their surroundings. This raises the acidity of the bog. Whilst the plant grows further at the top, it decomposes from the bottom upwards. The dead parts of the plant build up into layers of peat.
White peat under the magnifying glass
The top layer of peat consists of white peat. The structure of the plant parts can still be clearly recognised. By contrast with other habitats dead plants in the bog decompose very slowly. This is partly because the bog soil is damp, cool and acidic. This keeps off many of the small organisms that would otherwise shred the dead plant material into very small pieces. On the other hand the dead parts of the plant soon transform into an environment with very low oxygen content because of the high level of water, and this prevents microbial decomposition.
Brown peat under the magnifying glass
The middle layer consists of brown peat, a homogenous, featureless mass where plant structures can only be identified by scrutinising them very closely. Brown peat is created by the slow decomposition of the plant material in an oxygen deficient environment. This process is due to bacteria that release methane.
Black peat under the magnifying glass
The bottom and oldest layer of peat consists of black peat. Here it is almost impossible to recognise plant structures. It is created by the further decomposition of the plant material by anaerobic bacteria and the pressure of the layers of peat above.
Schema: Pressure under the magnifying glass
How bogs were created
The last ice age left behind shallow lakes on impermeable soils. After they silted up raised bogs came into being over thousands of years. Touch these surfaces with the palm of your hand and take a journey back in time through their history!
Schema 1 Monitor
12,000 years ago
The last Ice Age leaves behind shallow lakes. Undecomposed plant material (mud deposits) piles up at the bottom.
Schema 2 Monitor
The Early Stone Age
The lakes silt up. Boggy forest mires are created and peat mosses begin to grow.
Schema 3 Monitor
The Bronze and Iron Ages
The peat mosses replace the forest mires. The layer of peat grows and only feeds on rainwater.
Schema 4 Monitor
The 18th century
The bogs are dried out. The areas are used as farmland and pastureland. At first peat is dug out by hand.
Schema 5 Monitor
Peat exhausted areas are rewetted. Residual areas of quasi-natural raised bog are protected.
Bogs as climate guards
Growing plants absorb carbon dioxide (CO2), which is released once more when they die and begin to rot. But not in the bog: here it is stored in undecomposed plant material. This explains why bogs play an important role in protecting the climate.
In order to exploit bogs for commercial purposes they are dried up by ditches and drainages. They thereby lose their storage function. As water levels decrease the levels of soil which have hitherto been shut off from oxygen are once again exposed to the atmosphere and the microbial breakdown of the plant material begins. The carbon that has been stored in the soil for centuries is now released within a very short time and escapes into the air as CO2. If the soil is additionally fertilised with nitrogen this results in an increase in nitrous oxide (laughing gas), N2O, which is 300 times more damaging to the climate than CO2.
If we wish to protect the climate on a long-term basis we must put a speedy end to the exploitation of the bogs.
Starting screen: water levels
Bog protection is climate protection
Peat levels are built up when peat mosses are subjected to a process of photosynthesis. During this process carbon is permanently drawn off the atmosphere. When the bogs are dried out and used for commercial purposes the carbon dioxide which has been stored there for thousands of years is released once more within a few decades.
This process has a considerable influence on our climate: in Germany alone 31,000,000 tonnes of CO2 equivalents are released every year, 84% of which is caused by using bog areas for agricultural purposes, 9% comes from unused and rarely used areas, and 7% from the industrial extraction of peat for use as garden soil.
In order to ensure a healthy climate and our own future, bogs must therefore be protected and re-wetted.
A protective sponge
Natural bogs are unique ecosystems and important carbon stores. They also protect us because they retain water like a sponge.
Since peat has a huge swelling capacity the huge levels of peat in an intact bog function like gigantic water tanks. In heavy rain peat can absorb huge quantities of water that is subsequently only slowly released. This explains why bogs are valuable buffers against flood protection in winter and dry weather in summer. Furthermore the water they store regulates the temperature and ensures a balanced local climate.
When water flows through a bog it is filtered. The bog plants not only take their nutrients from the water but also pollutants like lead, copper and manganese. These are stored on a long-term basis in the growing levels of peat in an undisturbed bog. Thus bogs naturally protect groundwater and surface water from contamination.