SPATIAL VARIABILITY OF GROUNDWATER SOLUTE CONCENTRATIONS AT THE WATER-TABLE UNDER A PINE STAND ON SANDY SOIL WITH DEEP GROUND-WATER

Aim of the study was to prove the evidence of a direct influence of so lute input pattern (induced by canopy throughfall) on the pattern of g roundwater solute concentration at the water table even at sites with groundwater table of 4-5 m below surface. The test site was a weakly b uffered sandy soil with groundwater table ca. 4.3 m below surface (Pod zol soil with some features of former gley process) under a cultivated pine stand (age ca. 60 years). Groundwater at the water table was sam pled in between two rows of trees along a 30 m transect at 0.5 m inter vals. As example, the results for sulfate concentration (the key solut e of soil and groundwater acidification) show rather high variation al ong the transect. But a thorough stochastic analysis of empirical data sets reveals cyclic oszillations occurring synchronous and with same period length for sulfate concentration at the water table and for can opy coverage of the ground (and therefore for solute input). An additi onal long-periodic oscillation is strongly superimposing in the case o f sulfate concentration. Thus the results indicate a direct influence of the pattern of canopy throughfall on the pattern of sulfate concent ration at the water table. However, this influence is rather weakly pr onounced at this deep groundwater site compared to corresponding shall ow groundwater sites.