LONG-TERM SOIL Moisture Trends At the Marcell Experimental Forest.

Spatial and temporal patterns of shallow and deep soil moisture are a fundamental component of forest ecosystem dynamics. In the glacial till region of northern Minnesota, small changes in topography have profound influences on soil texture and thus soil water movement and ecosystem development. At the Marcell Experimental Forest (MEF), soil moisture has been collected seasonally and incrementally (every 0.3m, up to 3m deep) using the neutron probe method at 10 forested sites since 1961. This dataset is extremely unique and highlights the importance of monitoring long-term changes in soil moisture at varying depths. Seasonal trends in soil moisture were compared with long-term climatic data and positive relationships were found. In 2011, 25 additional sites were added to increase the spatial extent of the study and temporal sampling was extended to a bi-weekly schedule. The expanded dataset will be used to investigate a variety of research questions, such as the relationship between forest productivity and available soil water and the ecohydrological controls on available soil water at varying depths.