Perspectives from the peatland archive on ecosystem development and vegetation dynamics: building on the Minnesota legacy

Background/Question/Methods

The careers and contributions of Margaret Davis, Eville Gorham, and Herb Wright overlap in their concern with climate change, vegetation dynamics, and ecosystem structure as recorded in geohistorical archives.   Peatland sediments comprise one of these archives, and served as focal points for much of Gorham’s work on ecosystem development and carbon dynamics, as well as many of Wright’s contributions on climate change and ecosystem dynamics.  Although Davis’ work focused on sediment archives from lakes and forest hollows, peatland archives are now resolving some of the questions of climate change and forest dynamics to which she devoted much of her career.  Here, we review recent advances in the application of peatland archives to regional paleoclimate inference and global carbon dynamics, and discuss how independent paleoclimate and terrestrial vegetation records can be developed from peatland sediments to address mechanisms underlying upland forest dynamics.

Results/Conclusions

Peatlands are increasingly recognized as having critical roles in global carbon dynamics, serving as long-term carbon sinks as well as potential sources.  Recent and ongoing global syntheses link peatland carbon storage with Holocene climate change at centennial to millennial timescales.  These dynamics include carbon gain and loss in peatlands under climate change, but also involve both formation of new peatlands and lateral expansion of existing peatlands.  Recent studies of peatland initiation and development suggest that decadal-to-centennial scale climate excursions, including transient droughts, may serve as important triggers for peatland establishment and expansion.  Peatlands also contain sensitive records of past moisture variability, upland vegetation, and regional fire. Networks of lake and peatland records of vegetation and moisture variability allow examination of the relative roles of millennial-scale and centennial-scale climate changes in pacing tree species migrations, although chronological uncertainty remains high when comparing multiple records.  However, single cores from peatlands can be used to study the response of forest vegetation and disturbance to climatic change and extreme events with chronological precision and accuracy.  Recent and ongoing applications in the western Great Lakes region and eastern North America provide the means to assess potential mechanisms underlying Holocene dynamics of beech, hemlock, and other species.