Bodenzustand, Ernährungszustand und Wachstum von Fichten (Picea abies Karst.) auf Probeflächen des Friedenfelser Verfahrens in der Oberpfalz

The Friedenfels experiment was initiated in 1924 by the forester EBERT to ameliorate degraded podzol soils derived from phyllite in the northern part of Upper Palatia. The forester BAUR continued development of the project until 1931. The results of the experiment were derived from 3 experimental plots each with identical site properties representing 3 characteristic developmental stages of the approach with different amelioration intensities as well as from a reference area. Stem and foliar analyses were performed with 3 vital dominant Norway spruce trees on each plot. In addition, a characteristic soil profile per site was analyzed and soil chemistry (concentrations and total amounts of C and N, reaction and effective cation exchange properties) of the area around the sample trees was determined by area representative sampling. 7 decades after the start of the trials no amelioration effect could be identified on experimental plot I (addition of small amounts of CaO into the planting holes of spruce after litter removal beneath a thin shelter stand of Scots pine). The sample trees here suffered from severe N, (P, Mg) deficiency and their growth corresponded to site class 111.7 according to WIEDEMANN (1936). The amelioration on plot II (litter removal, liming with 30 dt ha¹ CaO before planting under a thin cover of Scots pine) accelerated growth for at least 40 years and resulted in an increase of base saturation and pH and a decrease of the C/N-ratio in the organic layer only. The spruce trees are still well supplied with all of the nutrients and are growing according to site class 1.6. The most intensive amelioration of experiment III (clear-cutting, removal of stumps and litter, deep tillage, liming with 40 dt CaO ha¹, and establishment of N-collecting species together with spruce) caused considerable C and N losses, but improved the C/N relations down to 30 cm depth. In addition, C concentrations, base saturation and the amount of exchangeable Ca in the uppermost mineral soil still show increases even 70 years after the manipulation. N, Ca and Mg nutrition of the trees is still adequate and they are growing according to site class I.1. From the results of these experiments conclusions are drawn with regard to an optimized amelioration technique under the present conditions and to the replication of liming.