What is moss, anyway?
Mosses do not have roots; they take invisible carbon dioxide gas from the air and absorb rain water through leaves and stems.By using a green pigment called chlorophyll within their cells, the moss uses energy from sunlight to convert the water and carbon dioxide into energy ‘stores’ in the form of carbon-based sugars, via a process known as photosynthesis. A byproduct is the release of oxygen into the atmosphere.
The moss links thousands of sugar molecules together to form cellulose, a very tough substance that forms the walls of plant cells.
In the hummock-forming or ‘bog-making’ sphagnum mosses, the network of green ‘photosynthetic’ cells is also surrounded by other special cells that simply hold and conduct water. This is how sphagnum moss can hold over 20 times its dry weight in water.
As the moss grows, its metabolism also creates acidic conditions in the local environment.
The growing moss can create a dense carpet, sealing off lower layers from oxygen in the atmosphere. The build up of dead lower stems in this waterlogged acidic environment means that it only partially decomposes; effectively it becomes ‘pickled’ and preserved.
Over time this material becomes compacted and compressed under the weight of the waterlogged moss carpet above and forms peat.