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Peter S. Curtis Department of Evolution, Ecology, and Organismal Biology The Ohio State University Managing Great Lakes Forests for Climate Change Mitigation UMBS Forest Carbon Cycle Research Program Slide 2 Two Definitions for this Webinar UMBS Forest Carbon Cycle Research Program Forest Management If and when to harvest trees. Climate Change Mitigation Reducing the rate of increase of atmospheric carbon dioxide. Reducing the rate of species loss due to climate change. Slide 3 Webinar Roadmap UMBS Forest Carbon Cycle Research Program A brief overview of the Great Lakes forests. Forests and climate change: what is the connection? Managing for carbon storage: to cut or not to cut. Biodiversity and ecosystem resiliency: are they important for climate change mitigation? Conclusions. Slide 4 UMBS Forest Carbon Cycle Research Program A Brief Overview of the Great Lakes Forests This is an ideal environment for growing diverse and productive forests. Presettlement forest area was about 89 million acres (140,000 sq miles). www.nrs.fs.fed.us Slide 5 These Forests Were Virtually Entirely Cut Between ~1860 and 1920 Michigan Archives Slide 6 Michigan: 82,000 ha (0.6% original forest) Wisconsin: 23,000 ha (0.2% original forest) Minnesota: 264,000 ha (2.4% original forest) The Extent of Primary Forest Remaining in the Lakes States (after Frelich 1995, Davis 2006) Slide 7 UMBS Forest Carbon Cycle Research Program Current Status of the Great Lakes Forests They cover about half of their original area. They bear little structural or compositional resemblance to the original forest. They are mostly young and homogeneous. www.nrs.fs.fed.us Slide 8 Forest age (years) WE ARE HERE EVEN-AGED (mostly aspen) UNEVEN-AGED (maple, oak, pine) ASPEN MORTALITY natural senescence, pathogens, insects Succession Many Stands Are Now at an Ecological Transition, Between Young and Potentially Old Community Types Slide 9 Northern Great Lakes: 643,000 ha (13% all timberland) Northern Superior Uplands: 104,000 ha (9% all timberland) Northern Minnesota: 369,000 ha (10% all timberland) Potentially Old Timberland (80-120 yrs) in the Lakes States Southern Superior Uplands: 830,000 ha (16% all timberland) Eastern Broadleaf Forest: 672,000 ha (19% all timberland) All timberland: 19,494,000 ha Potentially old: 2,747,000 ha (14%) Old: 464,000 ha (2%) (after Schmidt et al., 1996) Slide 10 UMBS Forest Carbon Cycle Research Program Forests and Climate Change: What is the Connection? Slide 11 What You Need To Know About The Forest Carbon Cycle NET PHOTOSYNTHESIS (Carbon In) ECOSYSTEM RESPIRATION (Carbon Out) CARBON STORAGE (OR LOSS) = Carbon In Carbon Out www.oup.co.uk/images/oxed/children/yoes/atoms/carboncycle.jpg Slide 12 The UMBS Forest Carbon Cycle Research Program Peter Curtis, Ohio State Univ. Gil Bohrer, Ohio State Univ. Chris Gough, Virginia Commonwealth Univ. Chris Vogel, Univ. Michigan Knute Nadelhoffer, Univ. Michigan Danilo Dragoni, Indiana Univ. This research is supported by the Office of Science, U.S. Department of Energy, through the Midwestern Regional Center of the National Institute for Global Environmental Change, and the National Institute for Climate Change Research. Slide 13 Ecological Studies of Forest Carbon Storage Permanent Study Plots at UMBS Slide 14 Meteorological Studies of Forest Carbon Storage Slide 15 Slide 16 UMBS Forest Carbon Cycle Research Program Managing for Carbon Storage: To Cut or Not to Cut Conventional Theory: Young Forests Sequester More Carbon Than Older Forests. Some Problems With Conventional Theory. Counter-theory: Carbon Storage Increases Following Ecological Transition in Great Lakes Forests. Slide 17 UMBS Forest Carbon Cycle Research Program Conventional Theory of Carbon Storage as Forests Age P G = Gross Production (photosynthesis), R = Respiration, B = Biomass, P N = Net Production (Carbon Storage) E.P. Odum. 1969. The Strategy of Ecosystem Development. Science 164. Wood production (slope of line B) and carbon storage (area of shaded P N ) are maximized in young forests. In forests > 100 yrs, both slow to near zero. Slide 18 Results From the UMBS Forest Provide Support For This Theory Annual C storage ( Mg C ha -1 yr -1 ) Annual carbon storage is variable, but lower than it was 40 years ago. UMBS Forest Carbon Cycle Research Program Gough et al. (2008) Slide 19 UMBS Forest Carbon Cycle Research Program Gough et al. (2008)Luyssaert et al. (2008) However, Meteorological Data From Around the World Shows Substantial Carbon Sequestration in Forests > 200 Years Old. Slide 20 UMBS Forest Carbon Cycle Research Program Forest Harvest, Even Selective Cutting, Can Result in Substantial Soil Carbon Losses Nave et al. (2010) Slide 21 UMBS Forest Carbon Cycle Research Program Counter-theory: Carbon Storage Can Increase With Forest Age Due to Increasing Ecosystem Structural and Biotic Complexity We are testing this theory at the Forest Accelerated Succession ExperimenT (FASET) A key variable is the amount of nitrogen available for plant growth. Slide 22 Biodiversity and ecosystem resiliency: are they important for climate change mitigation? More species that are ecologically similar means greater resistance to change Higher biodiversity = greater ecological resilience Slide 23 UMBS Forest Carbon Cycle Research Program At UMBS, More Diverse Forest Plots Are More Resilient to Carbon Storage Declines With Age Gough et al. (2010) Slide 24 UMBS Forest Carbon Cycle Research Program At UMBS, Older Plots That Are More Structurally Complex Have Higher Wood Production Hardiman et al. (in review) We measure canopy complexity (rugosity) with a laser rangefinder. Slide 25 UMBS Forest Carbon Cycle Research Program Moving Forward As Great Lakes forests age they generally become more structurally and biotically complex. This increasing complexity facilitates sustained carbon storage, greater ecological resilience, and enhanced species conservation. Forest management that mimics natural ecological succession may be possible at relatively small scales. The 7 million acres of 80-120 year old forest in the Lakes States should be allowed to naturally transition for maximal climate change mitigation impact. Slide 26 Conclusions Many Great Lakes forests will experience a major ecological transition over the next 25-50 years, with important implications for carbon cycle dynamics and climate change resilience. Great Lakes forests have been, and will continue to be, important sources of wood products, and many stands can be sustainably managed to meet these needs. Managing for climate change mitigation, however, argues for allowing natural ecological succession to proceed within many Great Lakes forests.