Final answer:
Lignin decomposition is hindered in peat bogs due to low oxygen and low pH conditions, causing the accumulation of partially decomposed plant material or peat.
Step-by-step explanation:
Peat bogs are unique ecosystems that occur in areas with stagnant water and low oxygen levels due to limited water flow and poor percolation. In these conditions, the rate of decomposition of organic material is significantly slowed down. Specifically, the decomposition of lignin, a complex organic polymer found in the cell walls of plants, is hindered under anaerobic (low-oxygen) conditions. Lignin decomposition requires oxidation, which is not possible without sufficient oxygen, leading to the accumulation of partially decomposed plant material, known as peat. Over time, the layers of peat can be subjected to downward pressure and eventually transform into coal. The low oxygen content, combined with organic acids produced during decomposition, also lowers the pH of the environment, creating challenges for plant growth and reducing the number of species that can exist in such an acidic and oxygen-poor environment.