Spatial distribution patterns and soil properties of lynchet systems in Northeastern Bavaria, Germany

Former field systems (FFS) in recent forest areas of Central and Northern Europe are often discernible by their characteristic morphology with slightly flattened slope areas and intermediary ridges formed by tillage and water erosion. Soils of such lynchet systems feature distinctly modified stratigraphy and properties and thereby constitute a memory of past land use. At the same time, the legacies of past agriculture affect recent forest ecosystems. High-resolution digital elevation models (DEMs) allow to identify lynchets over large areas and open up new opportunities to study the spatial distribution patterns and soils of FFS. Within our research on different land use legacy features in forest areas, we study FFS in Northeastern Bavaria (Germany) in a geopedological approach, combining large-scale mapping and spatial analysis with the description and analysis of soil properties for specific sites.

Lynchet areas (and other remnants of pre-industrial FFS) in recent forests were mapped from LIDAR DEMs for an area of 2045 km² (972 km² forest area). The mapping results show more than 100 km² of abandoned field systems within the study area, mostly appearing as lynchet systems. Their spatial distribution patterns differ within the study area, mainly depending on parent material and landform. In the limestone region of the Franconian Jura, FFS occur spatially dispersed, often as considerably small, irregularly shaped parcels, presumably reflecting proceeding abandonment of less productive and accessible fields with intensification of agriculture. In contrast, FFS in the Bohemian Massif in the eastern part of our study area were often found in compounds of many regularly shaped parcels, frequently associated with deserted settlement areas.

Soil stratigraphy and properties were studied for FFS and reference positions (forest areas with no indications of former agricultural use) in six study sites, combining detailed characterization of principal soil profiles and an assessment of spatial variations of soil properties in a near-surface sampling approach. First results show that FFS soils are characterized by truncated profiles over most parts of the treads and accumulation of colluvium confined to relatively small areas upslope of lynchet risers. The depth of soil profile truncation and height of lynchet risers differ, mainly related to slope and erodibility of the initial soils. Stratigraphy of the lynchet soils indicates a gradually proceeding formation. Carbon and nitrogen contents were found to differ between FFS and reference soils and to be more homogeneous within the FFS. Carbon contents were mainly lower in the FFS, while both lower and higher nitrogen contents were observed for FFS soils, presumably related to different duration and intensity of agricultural use.

Overall, the results show that the legacy effects of past agriculture affect large fractions of recent forest areas, and can be of different quality depending on lithology of the soils’ parent material and land use history.