Glacial Preconditioning of Alpine Peatland Formation

Peatlands are ecosystems that comprise the largest terrestrial carbon store on Earth. They play a critical role in climate change mitigation, while also supporting unique biodiversity, regulating water flow and serving as paleoecological archives. Understanding the history of peatland formation and present subsurface conditions is essential for effective conservation and restoration efforts. Past glacial processes have had a first-order impact on peatland development in both mountain environments and lowlands. Although the role of climate in peat initiation is well explored, the influence of glaciations on postglacial peat-forming processes remains poorly investigated.

Glaciers can provide suitable conditions for peatland formation by the ability to i) form local depressions and ii) deliver abundant fine sediments to induce ponding. However, the efficiency of glacial erosion strongly depends on geological factors like rock erodibility or basal topography. Other factors may in turn impede postglacial peat accumulation despite apparently suitable geological and climatic conditions. These include e.g. a high flood frequency, fluvial erosion in alluvial valleys, or, in mountainous environments, high landslide frequency.

To investigate peatland substrata, we apply a combination of geophysical methods, including ground penetrating radar and electrical resistivity tomography, and core drilling. We present characteristic peatland environments in central and perialpine settings and discuss how i) glacial depositional and ii) glacial erosional processes control their formation. In addition, we examine the onset of peat growth and rates of peat accumulation in formerly glaciated regions of the Eastern Alps.

These insights contribute to the understanding of present-day peatland ecosystem functioning, as subsurface stratigraphy often controls hydrological characteristics and vegetation patterns. Such knowledge is essential for peatland conservation and restoration strategies aimed at maintaining their role as important habitats and long-term carbon stores.