Differences in soil conditions between heathlands and grasslands on Zechstein gypsum soils

The distribution of heathland and grassland communities in respect to edaphic factors (exchangeable cations, organic C, total content of N, P) was investigated at two areas of the Zechstein belt in the southern part of the Harz mountains, Germany. Six transects, each with 12 quadrats of 0.5 x 0.5 m, were positioned in the transition zone of the two communities. Calluna vulgaris, Cladonia foliacea, C. rangiformis and Dicranum scoparium mainly occur in the heathlands, Galium verum, Euphorbia cyparissias, Thymus praecox, Brachypodium pinnatum and Koeleria macrantha in the grasslands. The results of CCA indicate a high correlation between the vegetation pattern and a gradient of pH value and soil depth. The humus layers of the Gypsum Rendzinas dominated by Calluna vulgaris show a diminished nutrient availability of N and P and they contain higher levels of Al and Fe in connection with lower pH values. In contrast, the soils under the grassland communities show higher pH values and thicker humus layers.