Managing Great Lakes Forests for Climate Change Mitigation Peter S. Curtis Department of Evolution, Ecology, and Organismal Biology The Ohio State University UMBS Forest Carbon Cycle Research Program Two Definitions for this Webinar 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. UMBS Forest Carbon Cycle Research Program Webinar Roadmap 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. 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 UMBS Forest Carbon Cycle Research Program These Forests Were Virtually Entirely Cut Between ~1860 and 1920 Michigan Archives The Extent of Primary Forest Remaining in the Lakes States Minnesota: 264,000 ha (2.4% original forest) Wisconsin: 23,000 ha (0.2% original forest) Michigan: 82,000 ha (0.6% original forest) (after Frelich 1995, Davis 2006) 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. www.nrs.fs.fed.us UMBS Forest Carbon Cycle Research Program They are mostly young and homogeneous. Many Stands Are Now at an Ecological Transition, Between Young and Potentially Old Community Types UNEVEN-AGED (maple, oak, pine) Succession ASPEN MORTALITY natural senescence, pathogens, insects EVEN-AGED (mostly aspen) Forest age (years) WE ARE HERE Potentially Old Timberland (80-120 yrs) in the Lakes States Northern Minnesota: 369,000 ha (10% all timberland) Southern Superior Uplands: 830,000 ha (16% all timberland) Northern Superior Uplands: 104,000 ha (9% all timberland) Northern Great Lakes: 643,000 ha (13% 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) Forests and Climate Change: What is the Connection? UMBS Forest Carbon Cycle Research Program What You Need To Know About The Forest Carbon Cycle ECOSYSTEM RESPIRATION (Carbon Out) 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 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. Ecological Studies of Forest Carbon Storage Permanent Study Plots at UMBS Meteorological Studies of Forest Carbon Storage 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. UMBS Forest Carbon Cycle Research Program Conventional Theory of Carbon Storage as Forests Age Wood production (slope of line B) and carbon storage (area of shaded PN) are maximized in young forests. In forests > 100 yrs, both slow to near zero. PG = Gross Production (photosynthesis), R = Respiration, B = Biomass, PN = Net Production (Carbon Storage) UMBS Forest Carbon Cycle Research Program E.P. Odum. 1969. The Strategy of Ecosystem Development. Science 164. -1 -1 NEP (Mg C haC-1hayr (Mg storage Annual C yr)-1) Results From the UMBS Forest Provide Support For This Theory 2.5 Source of variation harvest/fire harvest/fire 2.0 climate 1.5 disturbance 1.0 0.5 succession 0.0 -0.5 1900 1920 1940 1960 1980 2000 Year Gough et al. (2008) UMBS Forest Carbon Cycle Research Program Annual carbon storage is variable, but lower than it was 40 years ago. However, Meteorological Data From Around the World Shows Substantial Carbon Sequestration in Forests > 200 Years Old. Luyssaert et al. (2008) UMBS Forest Carbon Cycle Research Program Gough et al. (2008) Forest Harvest, Even Selective Cutting, Can Result in Substantial Soil Carbon Losses Nave et al. (2010) UMBS Forest Carbon Cycle Research Program 1.5 climate A rb climate y 2.0 C + Girdling 2.5 re co ve r 3.0 Hypothetical NEP Hypothetical N availability stu di an 1.0 ce NEP (Mg C ha-1 yr-1) 3.5 B 0.5 succession 0.0 -0.5 98 000 002 004 006 008 010 012 014 016 018 19 2 2 2 2 2 2 2 2 2 2 Year UMBS Forest Carbon Cycle Research Program - N available for plant growth 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. 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 At UMBS, More Diverse Forest Plots Are More Resilient to Carbon Storage Declines With Age Gough et al. (2010) UMBS Forest Carbon Cycle Research Program At UMBS, Older Plots That Are More Structurally Complex Have Higher Wood Production We measure canopy complexity (rugosity) with a laser rangefinder. UMBS Forest Carbon Cycle Research Program Hardiman et al. (in review) 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. UMBS Forest Carbon Cycle Research Program 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.