Comparative analysis of throughfall event response for 6 different forest stands

Rainfall redistribution by forest canopies differs between tree species and can play an important role for tree water availability and groundwater recharge. A thorough understanding of these relationships will improve our ability to predict future impacts of climate and forest structural changes on the water balance of forest stands.

In the TERENO observatory in the Müritz National Park (north-eastern Germany), throughfall was continuously measured at 7 sites with different dominant tree species and ages: young and old beech, young and old pine, and the mixed stands oak/beech, pine/beech, and pine/oak/beech. To this end, 5 trough-based throughfall monitoring systems with a total collecting area of 6.6 m² per site were installed at each site. Furthermore, stemflow was measured with tipping buckets at 5-10 trees per site. This added up to a total at 40 trees (18 pines, 15 beeches, 7 oaks) providing a unique high-temporal resolution data set of stemflow response. This dataset covers almost 5 years, offering a good data base for detailed event analyses.

During the measurement period we identified 534 rainfall events. However, to maintain good comparability, we removed all events where more than one of the five trough systems per site failed, which left us with 346 rainfall events for throughfall and 184 rainfall events for stemflow. Due to the large number of events we were able to compare winter and summer events as well as the influence of different precipitation characteristics. Statistical models were used to investigate forest-stand specific relationships between throughfall and meteorological conditions. The comparison of these relationships between the forest stands offered additional insights into forest structural controls of throughfall.