Response patterns in throughfall, stemflow and soil moisture: a high-resolution data set covering different forest stands

Abstract:

Rainfall redistribution by forest canopies differs between tree species and can play an important role for soil moisture patterns 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 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. Additionally, soil moisture was measured at 30 locations per site. The measured time series extend over 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. In a next step, the data from the soil moisture monitoring network allowed for a direct assessment of how the response patterns of throughfall and stemflow observed in the different forest stands impact soil moisture dynamics.