2005 Ton Damman Award Recipient

Paul Henne, of the University of Illinois Urbana-Champaign, has won the 2005 Ton Damman award for his paper Spatial and temporal response of forest communities to variation in lake-effect snow in northern Lower Michigan co-authored with F. S. Hu and presented at the 2005 ESA meeting in Montreal. Paul's research combines GIS and paleoecology techniques to examine variation in forest communities over spatial and temporal gradients in lake-effect snow. Here is the abstract of his winning paper

Spatial and temporal response of forest communities to variation in lake-effect snow in northern Lower Michigan

Reductions in snow extent and duration are expected in northern temperate ecosystems in response to global warming. However, the ecological impacts of such changes remain uncertain. The Great Lakes region provides a unique opportunity to examine community response to snowfall variability because it contains fine-scale heterogeneity of forest communities, and a strong gradient in annual snowfall due to the occurrence of lake-effect snow (LES). We coupled GIS and lake-sediment analyses to examine how spatial and temporal variations in LES interact with glacial landforms to impact forest communities in northern Lower Michigan. GIS analysis revealed the spatial correlation of upland tree species with LES. Today, northern hardwoods (e.g. Fagus, Acer) dominate on all landforms (e.g. outwash, till) within the lake-effect snowbelt (SB) but are restricted to fine-textured soils in nearby areas outside of the SB. We evaluated this vegetation-snowfall relationship during the Holocene by comparing and pollen records from two SB and two non-SB lakes. To control for the influence of landform one lake in each snowfall regime is situated on outwash, and the other on till. In both the SB and non-SB a stepwise decline in occurs circa 7000BP in response to a regional increase in moisture. However, around 5000BP, becomes consistently (0.5-1‰) more depleted within the SB relative to the non-SB. The larger magnitude of the decline within the SB probably reflects the input of LES because LES results from depleted vapor from the Great Lakes. Principle component analysis of pollen percentages reveals two distinct vegetation types in the past 7000 years: a xeric type dominated by Pinus, and a mesic type dominated by northern hardwoods. At both SB sites a clear shift from xeric to mesic vegetation occurs circa 5000BP. A similar shift never occurred outside the SB. Differences in vegetation associated with snowfall (SB vs. non-SB) are far greater than differences due to landform (till vs. outwash). These data indicate that snowfall exerts a dominant influence on the ecological processes controlling spatial and temporal variation in forest communities around the Great Lakes.