Dynamik des wasserhaushalts eines buchen-kiefern-altbestandes in nord-Ostdeutschland (Brandenburg)

The water balance of a mature beech and pine stand was evaluated over a 6-yr period (1998-2003) at the intensive monitoring site at Neuglobsow located in the northeastern German lowlands. The water model Expert-N was used to predict water fluxes, i.e. transpiration, evaporation, soil water storage and groundwater recharge by two different model approaches based on the Richards equation and the capacity approach. Additionally, the results of the chloride balance could be compared with the modeled evapotranspiration and groundwater recharge. Annual observed throughfall amounted to 406 mm and was almost similar to predicted evapotranspiration of 396 and 406 mm a^-1. The mean groundwater recharge was low and varied annually between 19 and 26 mm, whereas the chloride balance results in a groundwater recharge of 57 mm a^-1 which was twice as high as model predictions. The results show the variance of water balance components, which is closely related to different model applications. On the other hand small differences of the two approaches, e.g. transpiration or evaporation, are confirming the modelled values. As a consequence, due to a recent climate change with decreased precipitations during vegetation time, trees with a lower water demand should be more considered in future silvicultural practice, especially at sites with deeper groundwater levels and low soil water capacities.