We have modernized the process of reflected light imaging and image analysis with tree rings. We continue to refine our process for meticulous tree-ring data development in a high throughput, low cost work flow that leveraging emerging technologies. Operationally, we produce high quality and ultra high resolution image archives to complement entire collections of physical specimens. We continue to develop open source tools for image analyses and curation in a cloud native software platform.

Winter climate extremes over North America

With a focus on extreme events and the winter season, we are researching atmospheric circulation and related hydroclimate across North America. Through synthesis of paleoclimate proxy data, modern records, and output from model experiments, we will test hypotheses about recent increases in winter season climate variability and spatial synchrony within a multi century framework. This collaborative project involves a substantial component of tree-ring dataset development in California and around the Lake Superior region, and connects the UMN Griffin Lab with Steve Voelker's team at Michigan Tech, and Simon Wang's Climate Dynamics group at Utah State University.  This work is supported by the US NSF Paleo Perspectives on Climate Change (P2C2) program, award 1903504 .

Figure: Composite anomaly map of water year precipitation for extreme wet years in central California, data from PRISM.

Upper Mississippi River floodplain forests - past and future

Floodplain forests along the Upper Mississippi River are heavily managed and poorly understood ecosystems that provide myriad critical services to social and natural systems. Climate change, specifically warmer winters and more erratic summer precipitation patterns, are already modulating hydrologic patterns including flooding duration, and intensity. Leveraging existing research-management partnerships, this project will co-produce knowledge and tools to guide sustainable decision making. Combining several forms of big data, scenarios of past and future hydrology, and process modeling, we will investigate flood pattern variability and floodplain forest stand dynamics to identify climate-resilient targets for adaptive forest management. A collaboration led by Drs. Molly Van Appledorn, Marcella Windmueller-Campione, and Daniel Griffin, this project brings together researchers from the U.S. Geological Survey and the University of Minnesota with forest and hydrology management practitioners from federal, state, and non-governmental organizations. This work is supported by the USGS Midwest Climate Science Adaptation Science Center.

Figure: University of Minnesota researchers collect tree-ring increment cores from old silver maple in the Upper Mississippi River floodplain.

Climate, fire & savanna tree growth in a long-term burn experiment

In Minnesota, the interaction of fire and climate modulate oak tree dominance in the increasingly rare savanna ecosystem. Our group is working to disentangle the effects of fire and climate on oak savannas using a synthesis of experimental and observational data. We have focused our efforts at Cedar Creek Ecosystem Science Reserve, a LTER in eastern Minnesota where generations of scientists have made seminal contributions to modern ecological theory. Working with staff and scientists at Cedar Creek, we produced a large tree-ring dataset to study fire history, dendroclimatology, tree allometry, oak recruitment, and ecosystem biogeochemistry. This work is supported by the US NSF Division of Environmental Biology, award 1655144.

Figure: historical aerial imagery for 1938 (A) and 2016 (B) of the long-term burn experiment at Cedar Creek. Panels C - F illustrate stand level differences in canopy openness from 1938 to 2016. Source: MHAPO.


GriffinLab & Minnesota Dendro CollectiveDepartment of Geography, Environment & Society UNIVERSITY OF MINNESOTA