S pruce and P eatland R esponses U nder C limatic and E nvironmental Change Paul J. Hanson Environmental Sciences Division An experiment to assess the response of northern peatland ecosystems to increases in temperature and exposures to elevated atmospheric CO 2 concentrations

2Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary What is SPRUCE? A multi-year cooperative among scientists of the Oak Ridge National Laboratory operated by UT-Battelle, LLC and the USDA Forest Service Northern Research Station at the Marcell Experimental Forest in northern Minnesota →An experiment to assess the response of northern peatland ecosystems to increases in temperature and exposures to elevated atmospheric CO 2 concentrations. →Sponsored by the Office of Biological and Environmental Research within the US Dept. of Energy’s Office of Science.

3Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary An experimental system to measure the effects of environmental and atmospheric changes on peatlands. Study responses within a peatland to multiple levels of warming at ambient and elevated CO 2 levels, in a replicated design: –Warming levels from ambient to +9°C (above and below ground) inside large, open-top chambers. –Elevated CO 2 in the range of 800 to 900 ppm for the ambient and +9°C warming treatments.

Questions to be addressed How vulnerable are peatland ecosystems and their component organisms to atmospheric and climatic change? –Can we quantify the potential for shifts in local species dominance and regeneration success to assist projections of future biome changes over decades to centuries? –Will species assemblages or loss of species have unanticipated impacts on ecosystem processes? –Do changes in ecosystem services precipitate a change in state (e.g., loss of a dominant plant functional type)? To what degree will changes in plant physiology under elevated CO 2 impact a species’ sensitivity to climate or competitive capacity within the community? Will full belowground warming release unexpected amounts of greenhouse gases and solutes from high-C-content northern forests? –How will decomposition, nutrient cycling, and feedbacks on solute availability affect ecosystem productivity, solute efflux, and trace gas emissions? What are the critical air and soil temperature response functions for ecosystem processes and their constituent organisms? –Do those response functions for ecosystem processes depend on shifts in species interactions and composition? Will ecosystem services (e.g., biogeochemical, hydrological, or societal) be compromised or enhanced by atmospheric and climatic change? ECOSYTEM SCALESECOSYTEM SCALES microbial processes / plant species entire peatland ecosystems

5Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary The Picea – Sphagnum Ecosystem A Critical Ecosystem – The experiment will be conducted in a Picea mariana [black spruce] – Sphagnum spp. forest in northern Minnesota. – This ecosystem located at the southern extent of the spatially expansive boreal peatland forests is considered vulnerable to climate change and is expected to generate important greenhouse gas feedbacks to the atmosphere under changing future climates.

6Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary SPRUCE Project Setting The S1 bog watershed at the Marcell Experimental Forest of the Northern Research Station of the USDA Forest Service. North of Grand Rapids in Itasca County, MN Deer River Ranger District Chippewa National Forest A mix of uplands, bogs, fens, lakes, and streams in the Marcell hills moraine.

7Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary Looking into a 1974 Strip-cut Area 24 March 2010

8Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary SPRUCE will be conducted in the S1-Bog -- a well-studied hydrologic and ecological setting

9Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary By 2100 future terrestrial environments may be 4 to 8°C warmer than today (Solomon et al. 2007) depending on the location. An overlooked reality is that mean deep (>1m) soil temperatures will also rise with climate warming (Huang 2006). Experimental systems must be improved to provide the best atmospheric and soil conditions appropriate for characterizing terrestrial ecosystem responses to year 2100 scenarios -- air and soil warming by as much as 8 to 10 °C. Effective deep belowground heating requires an effective aboveground heating method capable of maintaining the same target temperature differential for deep belowground warming. ORNL’s Approach for Ecosystem Warming

A SPRUCE Experimental Plot Isolated belowground corral includes peat layers Recirculating forced- air heaters with internal air mixing provide above ground heating (x6 to 8) Belowground heating provided by gradual heat inputs from deep heating probes located away from the target biology A movable roof could be added to this chamber during non-precipitating night hours to reduce operational costs. PrecipitationDeposition Radiation 12 m diameter, 8 m tall, deep heating at -2 to -3 meter

11Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary In larger plots, circumferential heating is supplemented with interior deep-only heating to maintain uniform warming throughout the soil volume. Belowground heating designs to accommodate full ecological diversity have been simulated and are being constructed for testing for application to the whole-ecosystem manipulations in the replicated study in the S-1 bog. Simulated Differential Temperature Contours (°C)

12Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary

13Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary

14Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary Experimental Blocks And Approximate Plot Positions: Shorter trees Uniform peat depth Standard age Block 4 Block 3 Block 2 Block 1

15Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary System Modeling of Biogeochemical Cycles and Organism Responses Carbon, water, energy, and nutrient exchange GPP, Respiration, Allocation Variable acrotelm depth and activity Variable catotelm activity Light penetration to foliage and Sphagnum (sun vs. shade issues) Hummock and hollow issues Ground area coverage Heterotrophs: CO 2 vs. CH 4

16Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary

17Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary Why we do ecosystem experiments: As a US DOE laboratory Oak Ridge National Laboratory Scientists seek to understand the implications of energy and energy use technologies on humans and the Environment. We plan and conduct targeted experiments to predict vulnerability of important terrestrial ecological systems and their function to projected changes in climate and atmospheric composition We develop experimental platforms for testing mechanisms controlling vulnerability of organisms, ecosystems and ecosystem functions to a range of temperature, precipitation, CO 2, and air pollution treatments for important ecosystems.

18Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary SPRUCE

19Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary Project Organization

20Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary

21Managed by UT-Battelle for the U.S. Department of Energy SPRUCE Experiment Summary Complex fluid dynamics simulations are being used to enhance our system design for field applications. wind