Soil microbiochemical properties as indicators for success of heathland restoration after military disturbance

Decline of heathlands in Central Europe raises the question of successful restoration of degraded heathlands. We examined the impact of different restoration techniques on soil microbial biomass carbon (C_mic,) and nitrogen (N_mic) and enzyme activity on an abandoned military training site in the Lüneburger Heaths. The aim was to determine which technique resulted in typical heathland soil conditions. The training site was in use for about 50 years. Vegetation and soils were degraded in large areas. Restoration actions were: (1) spreading of heath plaggen (sods, containing the organic layer and a few centimetres mineral soil), (2) spreading of heath plaggen and grass seeds (Festuca filiformis Pourr.), (3) spreading of F. filiformis-seeds and (4) succession (episodical tree removal). Ten years after restoration, we measured pH, bulk density, abundance of roots, soil organic carbon (SOC), nitrogen (N_t), phosphorus (P_t), C_mic, N_mic and acid phosphatase activity (AcP) in the first 10 cm of the mineral soil. Four restoration treatments were compared with one reference site. The reference site is heathland located near the training site, where no military actions took place. At all disturbed sites, bulk density and pH proved to be higher than on the reference site. Relative to the reference site, SOC storage reached from 37 to 91 per cent, regeneration of N_t was slightly lower. In contrast to the advanced development of SOC and N_t, the regeneration of C_mic and N_mi was much lower (15-44 per cent). The succession site showed a low pool of SOC, N_mic and N_mic but microbial ratios indicated a less disturbed C- and N-cycle. AcP pronounced differences in nutrient demand between disturbed sites and reference. On this base, recommendations for restoration management were given.