Effects of historical charcoal burning on soil landscapes in West Connecticut, USA

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Relict Charcoal Hearths (RCHs), also referred to as Charcoal Kiln Remains (CKR), are small anthropogenic landforms that are typically found in historical mining areas of low mountain ranges in Europe. Recent findings of several thousand RCHs in the North German Lowland and the use of very accurate Digital Elevation Models (DEMs) have increased awareness that historical charcoal production may significantly contribute to Late Holocene landscape change. In addition to the historical and archaeological aspects of RCHs, the potential implications of charcoal burning on ecosystems, including changes in physical and chemical properties of soils, increased stocks of soil organic carbon (SOC) and effects on plant growth, are worthy of investigation identified. There is a tremendous gap in the knowledge regarding the general ecological significance of RCHs as we are just starting to realize the greater dimensions of large RCH landscapes that have been recently. Charcoal production occurred in several regions in the Northeastern United States, although its effects on the landscape remain widely unknown. Recently, a first evaluation of shaded-relief maps (SRM) has revealed over 3,000 RCHs in a 40 km2 large area in Pennsylvania and more than 20,000 RCHs in a 1170 km2 large area in Litchfield County in Northwestern Connecticut. These results suggest a completely new picture of human impacts on soil landscape evolution in the Northeastern USA. A comparatively high density of RCHs is located in Litchfield Hills near the town of West Cornwall in Litchfield County, Connecticut. The RCHs are especially well preserved on slopes of the Housatonic River tributary valleys and form circular platforms with diameters normally less than ten metres. It is remarkable that currently the region is densely forested and the remains of former charcoal production, although only 125 years old, are completely obscured. Further research on RCHs is needed to enhance our understanding of the environmental consequences of historical charcoal production and examine the quantity and quality of this legacy effect on our modern ecosystems. Litchfield Hills are ideal for studying the properties, development and distribution of RCH-controlled soils and to gain new insights into anthropogenic soil landscapes in general.