The impact of arable and forest land use on soil pH, carbon and nitrogen concentrations and storages, and vegetation was investigated 27 years after a first survey in the loess region of lower Frankonia, Germany (sites Rodheim and Essfeld). At the two experimental sites, 8 luvisols and stagnic luvisols were described in the field, classified, sampled and analyzed. The pH values (KCl) increased in the arable soils after 27 years down to 120 cm depth by about one unit to 7.2. The development of the soil reaction under forest was more heterogeneous and did not show any temporal trend. In the forest soils the storage of both soil organic carbon and total nitrogen (1 m depth) clearly increased within 27 years. C(org) storage in Rodheim and Essfeld was 103.4 and 104.4 t ha(-1) (1969: 90.9 and 92,7 t ha(-1)), respectively, while the N(t)-stocks amounted to 12.4 and 13.0 t ha(-1) (1969: 9.6 and 11.4 t ha). The largest difference was found in the top soil horizons, where in the Ah-horizon under forest the organic carbon and total nitrogen increased to about 80%. In the arable soils the carbon stocks decreased in Rodheim from 98.1 to 91.1 t ha(-1) and in Essfeld from 85.3 to 83.7 t ha(-1), respectively. However; the N stocks increased in a way similar to the forest soils from 12.0 to 14.6 t ha(-1) (Rodheim), and from 11.0 t to 13.1 t ha(-1) (Essfeld), respectively. Again, as in the forest sites, the largest changes in the arable soils occurred in the humic A horizons.

The intensively used Rodheim forest (Galio - Carpinetum asaretosum) is patched and highly influenced by forest management. The high site heterogeneity causes a mosaicly; small-scaled ground vegetation pattern. In the Essfeld community forest (Galio - Carpinetum asaretosum) a sustainable forest management dominates with selective harvesting and results in a close-tonature structure. The species structure in both forests strongly changed during the 28 (32) years since the first survey towards plants indicating eutrophication and ruderal environment. At both arable sites the percentage cover of typical weeds and the number of accompanying species decreased. The species spectrum increased in favor of persistent weeds such as Cirsium arvense, Elytrigia repens and Poa annua at the expense of more sensitive species such as Papaver rhoeas, Myosotis arvensi, Aethusa cynapium, Anagallis arvenris, Viola arvensis and Cerastium glomeratum.