Experiments on Breakdown of Sphagnum in Two Bogs

Accumulations of organic matter have for long excited interest. Depths of peat greater than 30 cm are usually formed in waterlogged conditions and it is usually supposed that the peat accumulates owing to a slow rate of breakdown. This appears to be true of at least two Sphagnum dominated bogs where it has been found that the rates of production are in the range 2-12 metric tonnes/ha/year (unpublished data). These amounts are not unusually large for the region and climate in which they occur. Whether or not different species of Sphagnum break down at the same rate is not known, nor has there been much investigation of the factors affecting the rate of breakdown. There is a good deal of evidence (for example, Waksman Theander 1954; Kox 1954) to show that various chemical constituents of Sphagnum are lost at different rates, but it is not known to what extent the slow loss from old peat in natural conditions can be explained by its large proportion of residual constituents resistant to decay in these conditions. The experiments reported here have been made to investigate these questions.