Charcoal hearth soils: A tremendous environmental and cultural heritage

Charcoal making is one of the oldest forms of forest exploitation, civilizations being used to convert wood into charcoal for energetic and metallurgic purposes for thousands of years. For this purpose, firewood domes were built in the forests in appositely shaped emplacements, then left to burn for days under controlled semi-anoxic conditions. Lots people were involved over time, directly or indirectly, in this activity, which has left a trace in the collective memory and has shaped a variety of landscapes. In Europe, charcoal production was particularly widespread and in many cases lasted until a few decades ago, when charcoal demand collapsed and the residual production moved to few industrial installations. The legacy of such an activity is a plethora of abandoned charcoal hearths, where soil shows a thick, black, charcoal-rich top layer, which often overlies a complex sequence of pedogenic horizons that reveals successive land uses and/or climatic phases. Charcoal heart sites can be considered as ecological micro-islands, being often characterized by a peculiar understory and by lack of tree regeneration. A multidisciplinary study of relict hearth soils – based on pedology, history, anthracology, landscape ecology, archaeology, and forestry – may allow reconstructing past forests composition and exploitation, as well as the ecological and socio-cultural history of the region. Charcoal hearth soils are also impressive carbon reservoirs, particularly appreciable in terms of contrast to climate change, as much of the carbon present in them is charcoal, which is a form of carbon with extremely long residence times in soil. This contribution deals with some studies we carried out in Tuscany (Italy), which demonstrate the high potential of charcoal hearth soils for storing carbon and revealing the evolution of the landscape over time, including its anthropic component. Forest management should also be aimed at preserving charcoal hearth soils, with their important environmental and historical significance.