Acrotelmlager

Acrotelmlager are the upper, dynamic layers of peat in peatlands that lie between the surface and the deeper, more stable catotelm. The term acrotelmlager derives from the concept of an acrotelm, the upper zone in which water table fluctuations, plant roots, and aerobic microbial activity are most pronounced. In peatland science, acrotelmlager contrast with the catotelm, the lower portion where decomposition occurs more slowly under more anoxic conditions.

These layers vary from a few centimeters to well over a meter in thickness, depending on climate, hydrology, vegetation, and peat accumulation rate. They are characterized by periodic drying and rewetting, higher oxygen availability near the surface, and a relatively rapid turnover of recent plant litter. The acrotelm interfaces with the atmosphere and the catotelm, governing exchanges of water, nutrients, and greenhouse gases, and shaping the peatland’s vertical carbon architecture.

Functionally, the acrotelm acts as a dynamic interface for carbon storage and release. Under saturated conditions, aerobic decomposition is limited and methane production remains subdued, while droughts or drainage can raise oxidation and carbon loss as CO2. The acrotelmlager also support vascular and moss vegetation that influence water balance, peat formation, and resilience to environmental change.

Ecologically and climatically, changes in hydrology and temperature can alter acrotelm thickness and function, affecting peatland carbon balance and biodiversity. Human disturbances such as drainage, land-use change, or peat extraction can compromise the integrity of the acrotelm, accelerating peat loss and intermittently increasing emissions.

Related terms include acrotelm and catotelm in peatland science.