NUTRIENT POOLS AND FLUXES OF THE GROUND VEGETATION IN CONIFEROUS FORESTS DUE TO FERTILIZING, LIMING AND AMELIORATION

The effects of fertilization and amelioration treatments on some nutri ent pools and fluxes of ground vegetation in mature pine and spruce st ands on acid soils in South Germany are described. In N-limited pine f orests with moderate canopy density and with Deschampsia flexuosa an a dditional N-accumulation in biomass of 20-40 kg ha(-1) occurred 3 year s after pure N-fertilization. The N, P, K-cycling through ground veget ation was stimulated more than 10 years by a combined N + CaCO3 + P tr eatment leading to a shift in dominance from cryptogams and Ericaceae towards Deschampsia flexuosa and ruderal species like Epilobium angust ifolium. The effect of a lupine treatment (combined with initial soil preparation, liming and P supply) was far stronger than the effect of the other experimental procedures. But the fertilizer and amelioration effects on the herb layer of pine forests tended to decline after two decades for different reasons. The shade-tolerant ground vegetation i n a nitrogen-saturated spruce forest was not able to prevent heavy add itional nitrate losses from upper mineral soil after dolomitic liming. But the Ca, Mg and K fluxes through ground vegetation were strongly e levated in the third year after treatment.