Peat forms in waterlogged environments where plant material accumulates faster than it decomposes.

The accumulated organic material creates a dense, compressed matrix that has several distinctive chemical properties.

Peat is typically acidic — pH values in peat bogs can be quite low, which slows bacterial activity and inhibits many decomposers.

More importantly, the waterlogged environment in peat is anoxic, or oxygen-depleted: the water in the interstices of the peat contains very little dissolved oxygen because the organic material in the peat consumes it.

Without oxygen, many of the most important decomposers — aerobic bacteria — cannot function.