Journal of This Issue: FORESTRY Forest Carbon Stocks and Flows October/November 2011 Volume 109, Number 7S

SUPPLEMENT TO

Society of American Foresters Journal of This Issue: FORESTRY Forest Carbon Stocks and Flows October/November 2011 Volume 109, Number 7S

Climate–Forest Interactions

Biomass Use and Feedstock Issues

Wood–Fossil Fuel Substitution Effects

Forest Carbon Policies

Integrating Forests into a Rational Policy Framework

Managing Forests because Carbon Matters: Integrating Energy, Products, and Land Management Policy A Society of American Foresters Task Force Report

www.jofonline.org Journal of JoF FORESTRY

Editor W. Keith Moser, CF, [email protected] Managing Editor Matthew Walls, [email protected] Journal of Associate Editors Stanley T. Asah, recreation • Keith A. Blatner, education & communication • Don Bragg, forest ecology • Stephen Bratk- ovich, utilization & engineering • Russell Briggs, CF, soils & hydrology • Dean Coble, measurement • Dean Current, international forestry • Robert Deal, silviculture • John Groninger, silviculture • Sean Healey, geospatial technologies • Shibu Jose, forest ecology • Michael Kilgore, economics • Mee-Sook Kim, entomology & pathology • Jeffrey Kline, economics • Karen Kuers, silviculture • David Kulhavy, entomology & FORESTRY pathology • James G. Lewis, history • Valerie Luzadis, social October/November 2011 (supplement) Volume 109, Number 7S sciences • Michael G. Messina, silviculture • Cassandra Mose- ley, policy • Michael J. Mortimer, policy • David Nowak, urban & community forestry • Jay O’Laughlin, policy • Brian Oswald, • • fire John G. Peden, recreation Barry Rosen, international COMMENTARY forestry • Kevin Russell, wildlife management • Terry Sharik, education & communication • John Shaw, silviculture • Susan Stewart, social sciences • Thomas A. Waldrop, fire • Pat S5 Publisher’s Note Stephens Williams, human dimensions • Michael Wing, M.T. Goergen Jr. geospatial technologies Book Review Editor SAF TASK FORCE REPORT James E. Coufal, [email protected] Manuscript Manager Managing Forests because Carbon Matters: Linda Edelman, [email protected] Integrating Energy, Products, and Land Management Policy Production Editor R.W. Malmsheimer, J.L. Bowyer, J.S. Fried, E. Gee, R.L. Izlar, R.A. Miner, Cynthia Owens, [email protected] I.A. Munn, E. Oneil, and W.C. Stewart Publisher Michael T. Goergen Jr., [email protected] S7 Abstract Director, Advertising Scott Oser, [email protected] S8 Preface Editorial Offices and Advertising Sales 5400 Grosvenor Lane, Bethesda, MD 20814-2198 S9 Executive Summary (301) 897-8720 • fax (301) 897-3690 • www.safnet.org Correspondence: Address all letters to the editor to Jour- section 1 nal of Forestry Editor or e-mail [email protected]. Ad- dress correspondence relating to manuscripts to the Man- aging Editor. Address all advertising queries to the S13 Introduction Advertising Manager. Permission to reprint: Individuals, and nonprofit librar- section 2 ies acting for them, may make fair use of the material in this journal, for example, copying an article or portion of an article for use in teaching or research. Individuals may also S14 Forest Carbon Stocks and Flows quote from the publication if the customary acknowledge- ment of the source accompanies the quotation. To request permission to make multiple or systematic reproductions or section 3 republish material (including figures and article excerpts) contact the Copyright Clearance Center, Customer Service S21 Climate–Forest Interactions Department, 222 Rosewood Dr., Danvers, MA 01923; (978) 750-8400; fax (978) 750-4470; www.copyright.com. A fee for commercial use will be determined depending on use. section 4 Subscriptions: Subscription options and prices are available at www.jofonline.org. Subscription price to members of S24 Biomass Use and Feedstock Issues the Society of American Foresters is included in annual dues. Single Issues: $12 (individuals), $24 (institutions). Con- section 5 tact [email protected] to determine availability. The Journal of Forestry (ISSN 0022-1201) (IPM # S27 Wood–Fossil Fuel Substitution Effects 1115308) is published in January/February, March, April/ May, June, July/August, September, October/November, and December by the Society of American Foresters, 5400 section 6 Grosvenor Lane, Bethesda, MD 20814-2198. ©2011 (supplement) by the Society of American Foresters. Periodicals S35 Forest Carbon Policies postage paid at Bethesda, MD, and at additional mailing offices. Printed in the USA. POSTMASTER: Send address changes to Journal of Forestry, 5400 Grosvenor Lane, Bethesda, MD 20814-2198; [email protected]. Society of conclusion American Foresters S40 Integrating Forests into a Rational Policy Framework President Roger A. Dziengeleski, CF, Gansevoort, NY, rdziengeleski@ S41 Literature Cited finchpaper.com S49 About the Task Force Vice-President H. William Rockwell Jr., CF/FCA, St. Johns, MI, [email protected] S51 Subject Index Immediate Past-President Michael B. Lester, CF, Mechanicsburg, PA, [email protected] DEPARTMENTS Executive Vice-President and Chief Executive Officer Michael T. Goergen Jr., Bethesda, MD, [email protected] S52 Journal of Forestry Quiz

Council Robert L. Alverts, CF, Tigard, OR • Michael J. DeLasaux, Quincy, CA • Mark P. Elliott, Daphne, AL • George F. Frame, CF, Bristol, NH • Ernest A. Houghton, Gladstone, MI • Kenneth W. Jolly, Annapolis, On the cover: Composite image design by US Forest Service, Paciﬁc Northwest Research Station. Photo MD • Charles W. Lorenz, CF, Turnwater, WA • Ian A. Munn, CF, credits: “Carbon Smart”: top, Tom J. Iraci; middle, m.o.daby design LLC; bottom, Stephen M. Jolley. Mississippi State, MS • G. Lynn Sprague, Garden City, ID • Thomas J. Straka, CF/FCA, Pendleton, SC • William David Walters, CF, “Not So Much”: top, Daniel G. Brown; middle, Tom J. Iraci; bottom, unknown. Murfreesboro, TN

Forest Science and Technology Board Kurt W. Gottschalk, CF, chair • Andrew Sanchez Meador, forest resources • William F. Elmendorf, nonindustrial forestry • Matthew McBroom, forest ecology & biology • David Shaw, forest management & utilization • Sayeed Mehmood, decision sciences • Phillip Smartt, social & related sciences • Paul F. Doruska, CF, northern regional representative • David B. South, southern regional representative • Guy Pinjuv, western regional representative

House of Society Delegates E. Lynn Burkett, chair • Andrew J. Hayes, CF, vice-chair

National Office Department Directors Michael T. Goergen Jr., executive vice-president & chief executive officer • Jorge Esguerra, senior director, finance & administration • Louise Murgia, CF, senior director, field services • Matthew Walls, senior director, publications • Christopher Whited, senior director, marketing & membership • Scott Oser, director, advertising • Carol L. Redelsheimer, CF, director, science & education

SAF Mission Journal of The Society of American Foresters (SAF) is the national scientific and educational organization representing the JoF FORESTRY forestry profession in the United States. Founded in 1900 Editorial Policy by Gifford Pinchot, it is the largest professional society for The Journal of Forestry welcomes scientific and editorial manuscripts that advance the profession of forestry by presenting significant developments and foresters in the world. The mission of the Society of Amer- ideas of general interest to natural resource and forestry professionals. Articles published in the Journal present, in a readable style, new and ican Foresters is to advance the science, education, technol- state-of-the-art knowledge, research, practices, ideas, and policies. Mini-reviews on topics of special interests are also published at the discretion of the ogy, and practice of forestry; to enhance the competency of editorial board. Manuscripts must not have been published previously and must not be under consideration for publication elsewhere. Acceptance for its members; to establish professional excellence; and, to publication is based on both editorial criteria and peer review. Manuscripts are evaluated for methodology, technical accuracy, breadth of appeal, clarity, use the knowledge, skills, and conservation ethic of the contribution, and merit. The Journal reserves the right to publish countering or supplemental articles to promote discussion. profession to ensure the continued health and use of forest ecosystems and the present and future availability of forest resources to benefit society. SAF is a nonprofit organization Submission Guidelines meeting the requirements of 501 (c) (3). SAF members Letters to the Editor—Letters should directly address ideas or facts presented in the Journal. Priority is given to letters no longer than 250 words that refer include natural resource professionals in public and private to material published within the past six months. Letters may be faxed to (301) 897-3690, attention Editor, e-mailed to [email protected], or mailed settings, researchers, CEOs, administrators, educators, and to Editor, Journal of Forestry, 5400 Grosvenor Lane, Bethesda, MD 20814-2198. students. Exploring the Roots—These short introductions revisit seminal articles previously published by SAF and discuss topics of historical import to the field of SAF Core Values forestry, as well as explore the historical basis for issues currently affecting forestry. Maximum length is 1,000 words. Proposals for Exploring the Roots 1. Forests are a fundamental source of global health and columns may be e-mailed to [email protected], faxed to (301) 897-3690, attention Editor, or mailed to Editor, Journal of Forestry, 5400 Grosvenor human welfare, Lane, Bethesda, MD 20814-2198. 2. Forests must be sustained through simultaneously meeting environmental, economic, and community aspira- Perspectives—These short opinion pieces are not formally reviewed but are evaluated for content and style by the editors and/or editorial board. tions and needs, Maximum length is 1,000 words. The contributor of a “Perspective” must be a member of the Society of American Foresters. Submit the manuscript, 3. Forestersarededicatedtosoundforestmanagementand complete contact information, and a head-and-shoulders photograph online at www.rapidreview.com/SAF/author.html. conservation, and 4. Foresters serve landowners and society by providing Full-Length Articles—Maximum length is 4,500 words, plus a 150-word abstract. Footnotes should be incorporated into the text wherever possible or be sound knowledge and professional management skills. presented as endnotes. Full guidelines can be found online at www.jofonline.org. Submit your manuscript online at www.rapidreview.com/SAF/ author.html. Because the review process is double-blind, please ensure that authors are not identified anywhere in the manuscript (including running heads and feet).

Review Articles—Maximum length is 6,000 words, plus a 150-word abstract. Footnotes should be incorporated into the text wherever possible or be presented as endnotes. There is no limit to the number of literature citations in a review article. Full guidelines can be found online at www.jofonline.org. Submit your manuscript online at www.rapidreview.com/SAF/author.html. Because the review process is double-blind, please ensure that authors are not identiﬁed anywhere in the manuscript (including running heads and feet). Managing Forests because Carbon Matters: Integrating Energy, Products, and Land Management Policy

Robert W. Malmsheimer, James L. Bowyer, Jeremy S. Fried, Edmund Gee, Robert L. Izlar, Reid A. Miner, Ian A. Munn, Elaine Oneil, and William C. Stewart

The United States needs many different types of forests: some managed for wood products plus other benefits, and some managed for nonconsumptive uses and benefits. The objective of reducing global greenhouse gases (GHG) requires increasing carbon storage in pools other than the atmosphere. Growing more forests and keeping forests as forests are only part of the solution, because focusing solely on the sequestration benefits of the forests misses the important (and substantial) carbon storage and substitution GHG benefits of harvested forest products, as well as other benefits of active forest management. Forests and global climate are closely linked in terms of carbon storage and releases, water fluxes from the soil and into the atmosphere, and solar energy capture. Understanding how carbon dynamics are affected by stand age, density, and management and will evolve with climate change is fundamental to exploiting the capacity for sustainably managed forests to remove carbon dioxide from the atmosphere. For example, even though temperate forests continue to be carbon sinks, in western North America forest fires and tree mortality from insects are converting some forests into net carbon sources. Expanding forest biomass use for biofuels and energy generation will compete with traditional forest products, but it may also produce benefits through competition and market efficiency. Short-rotation woody crops, as well as landowners’ preferences—based on investment-return expectations and environmental considerations, both of which will be affected by energy and environmental policies—have the potential to increase biomass supply. Unlike metals, concrete, and plastic, forest products store atmospheric carbon and have low embodied energy (the amount of energy it takes to make products), so there is a substitution effect when wood is used in place of other building materials. Wood used for energy production also provides substitution benefits by reducing the flow of fossil fuel–based carbon emissions to the atmosphere. The value of carbon credits generated by forest carbon offset projects differs dramatically, depending on the sets of carbon pools allowed by the protocol

ABSTRACT and baseline employed. The costs associated with establishing and maintaining offset projects depend largely on the protocols’ specifics. Measurement challenges and relatively high transaction costs needed for forest carbon offsets warrant consideration of other policies that promote climate benefits from forests and forest products but do not require project-specific accounting. Policies can foster changes in forest management and product manufacture that reduce carbon emissions over time while maintaining forests for environmental and societal benefits. US policymakers should take to heart the finding of the Intergovernmental Panel on Climate Change in its Fourth Assessment Report when it concluded that “In the long term, a sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber, fibre, or energy from the forest, will generate the largest sustained mitigation benefit.” A rational energy and environmental policy framework must be based on the premise that atmospheric greenhouse gas levels are increasing primarily because of the addition of geologic fossil fuel–based carbon into the carbon cycle. Forest carbon policy that builds on the scientific information summarized in this article can be a significant and important part of a comprehensive energy policy that provides for energy independence and carbon benefits while simultaneously providing clean water, wildlife habitat, recreation, and other uses and values. Keywords: forest management, forest policy, forest carbon dynamics, carbon accounting, carbon offsets, life cycle assessment, building products substitution, bioenergy

Robert W. Malmsheimer is task force chair, and professor of Forest Policy and Law, SUNY College of Environmental Science and Forestry, Syracuse, NY. James L. Bowyer is professor emeritus, Department of Bioproducts and Biosystems Engineering, University of Minnesota, Minneapolis, MN, president of Bowyer & Associates, Inc., Minneapolis, MN, and director of the Responsible Materials Program in Minneapolis-based Dovetail Partners, Inc., Minneapolis, MN. Jeremy S. Fried is research forester, Resource Monitoring and Assessment Program, US Forest Service, Paciﬁc Northwest Research Station, Portland, OR. Edmund Gee is team leader, US Forest Service National Woody Biomass Utilization Team and coordinator, National Partnership, Washington, DC. Robert L. Izlar is director, University of Georgia Center for Forest Business, Athens, GA. Reid A. Miner is vice president for Sustainable Manufacturing, National Council for Air and Stream Improvement, Research Triangle Park, NC. Ian A. Munn is professor of Forestry Economics and Management, Mississippi State University, Mississippi State, MS. Elaine Oneil is research scientist, University of Washington, and executive director, Consortium for Research on Renewable Industrial Materials, Seattle, WA. William C. Stewart is forestry specialist, Environmental Science, Policy, and Management Department, University of California–Berkeley, Berkeley, CA. Copyright © 2011 by the Society of American Foresters.

Journal of Forestry • October/November 2011 (supplement) S7 Preface orest Management Solutions for Mitigating Climate Change in Reviewers the United States (Malmsheimer et al. 2008), by the Climate F Change and Carbon Sequestration Task Force of the Society Dennis Baldocchi Brooks Mendell of American Foresters (SAF), evaluated the implications of global University of California Forisk Consulting climate change for forests and addressed the role of forestry and at Berkeley LLC forests in mitigating climate change. Since that task force issued its Marilyn Buford Jay O’Laughlin report, the science and policies involving forests’ roles in climate US Forest Service University of Idaho change policies have evolved rapidly. Moreover, questions have arisen regarding how changes in the amount of forest biomass used Laura Draucker Marcia Patton-Mallory for energy and the trading of forest carbon for pollution credits World Resources Institute US Forest Service (offsets), motivated in part by climate change concerns, will affect Chris Farley John Perez-Garcia global climate benefits related to forests, forest ecosystems, and tra- US Forest Service University of Washington ditional forest products industries. Christopher Galik Naomi Pena In May 2010, SAF created a new task force to address those Duke University Joanneum Research issues and analyze United States’ forests, climate change, and energy policies. This article summarizes and examines our current under- Robert Fledderman Gary Rynearson standing of forest carbon stocks and flows; climate–forest interac- MeadWestvaco Green Diamond Resource Corporation Company tions; biomass use and feedstock issues; wood–fossil fuel substitution effects; and forest carbon policies. Our analysis focuses on US Andrew Gray Roger Sedjo rather than international forests and forest policies, although we do US Forest Service Resources for the Future examine pertinent international developments. Dale Greene Roger Sherman This article and the task force’s other products are the result of University of Georgia MeadWestvaco Corporation hundreds of hours by dedicated SAF volunteers. Many individuals assisted with the preparation of this article. We would especially like Thomas Harris Jacek Siry University of Georgia University of Georgia to thank Kelsey Delaney (SAF) for her administrative assistance and support of the task force, Sally Atwater (Editorial Arts) for editing Randall Kolka Kenneth Skog the article, Ken Skog (US Forest Service) for his assistance with data US Forest Service US Forest Service clarification in Section 5, Brad Smith (USFS Program Manager, Alan Lucier Timothy Volk Forest Inventory Analysis) for providing Figure 1 in Section 4, and National Council for Air and SUNY Environmental Science David Cleaves, Elizabeth Reinhardt, and David Wear (US Forest Stream Improvement and Forestry Service) for their assistance coordinating the review of this article by Margaret Mann Shira Yoffe agency experts. National Renewable Energy US Forest Service International Three individuals initially drafted small sections of this article. Laboratory Programs Dr. Jeffery Hatten (Mississippi State University) contributed the soil carbon dynamics in Section 2, Dr. Demetrios Gatziolis (USFS PNW Research Station) assisted on section 6’s assessment of carbon via remote sensing, and Dr. Marcia Patton-Mallory (USFS PNW Research Station) contributed to Section 6’s discussion of the strategic balance in managing carbon risk. In addition, this article was reviewed, in whole or in part, by the reviewers listed here and by others who wished to remain anonymous. To all of these individuals, Cite this article as: the authors express their sincere thanks. Their efforts significantly Malmsheimer, R.W., J.L. Bowyer, J.S. Fried, E. Gee, R.L. increased the article’s accuracy and scope. Izlar, R.A. Miner, I.A. Munn, E. Oneil, and W.C. Stewart. We have arranged this article topically. We believe that this 2011. Managing Forests because Carbon Matters: Integrat- organization will be useful to most readers. However, one conse- ing Energy, Products, and Land Management Policy. Jour- quence of this arrangement is that we discuss topics at various spatial and temporal scales in each section. We have attempted to nal of Forestry 109(7S):S7–S50. alert readers to these scale changes throughout the article.

S8 Journal of Forestry • October/November 2011 (supplement) Executive Summary

he United States needs many differ- role of forests as a source of products for Forest Carbon Stocks and Flows ent types of forests: some managed society and the effects of those products on Tracking the allocation of forest carbon T for wood products plus other bene- GHG concentrations. across live and dead trees, understory shrub fits and some managed for nonconsumptive US environmental and energy policies and herbaceous vegetation, the forest floor, uses and benefits. Management decisions need to be linked or at least be based on forest litter, soils, harvested wood products, must account for local conditions; landown- mutual recognition and should be based on and energy wood is far more difficult than ers’ objectives; and a broad set of environ- four basic premises grounded in the science conducting traditional inventories of com- mental, economic, and societal values. This summarized in this article: mercially valuable wood volume. Under- article considers how various forest and standing the dynamics of these allocations; wood use strategies can reduce accumulation 1. Sustainably managed forests can provide how they are affected by stand age, density, of greenhouse gases (GHG) in the atmo- carbon storage and substitution benefits and management; and how they will evolve sphere. while delivering a range of environmen- with climate change is fundamental to ex- The global carbon system stores carbon tal and social benefits, such as timber and ploiting the capacity for sustainably man- in various pools (stocks). Oceans and both biomass resources, clean water, wildlife aged forests to remove carbon dioxide forested and nonforested lands emit carbon habitat, and recreation. (CO ) from the atmosphere. to and absorb carbon from the atmosphere 2 2. Energy produced from forest biomass re- Carbon flux is usually estimated as in a two-way flow (flux). In contrast, carbon turns to the atmosphere carbon that change in carbon stocks. Several compli- removed from fossil fuel reserves acts as a plants absorbed in the relatively recent cations—deciding what comparisons or one-way flow because regardless of whether “pools” to include and what models, equa- emissions from fossil fuel combustion are past; it essentially results in no net release tions, and coefficients to rely on, accounting ultimately taken up by land, ocean, or for- of carbon as long as overall forest inven- for uncertainty and error, and even defini- ests, they are not returned to fossil fuel re- tories are stable or increasing (as is the tions of “tree” and “forest”—conspire to serves on anything less than a geologic time- case with US forests). make consistent, universally accepted esti- scale. Although there are many uncertainties 3. Forest products used in place of energy- in measuring carbon stocks and flows glob- intensive materials such as metals, con- mates grounded in objective science very ally, the objective of reducing global GHGs crete and plastics (a) reduce carbon emis- scarce. On average, carbon in the boles of suggests the importance of increasing car- sions (because forest products require less live trees, the best-sampled and most easily bon storage in pools other than the atmo- fossil fuel-based energy to produce), (b) modeled component of forest carbon inven- sphere. Growing more forests and keeping store carbon (for a length of time based tories, represents less than half the carbon in forests as forests are only part of the solu- on products’ use and disposal), and (c) the forest. tion. Focusing solely on forests’ sequestra- provide biomass residuals (i.e., waste Unmanaged forests do not provide ad- tion benefits misses the important (and wood) that can be substituted for fossil ditional climate benefits indefinitely. The substantial) carbon storage and substitu- fuels to produce energy. age when annual forest carbon storage incre- tion GHG benefits of harvested forest prod- 4. Fossil fuel–produced energy releases car- ments begin to decline varies but generally occurs in the first 100–150 years as tree ucts, as well as other benefits of active forest bon into the atmosphere that has resided mortality losses increase. In most of the management. in the Earth for millions of years; forest American West, fire and insects pose a very An assessment of the consequences of biomass–based energy uses far less of the immediate threat of catastrophic loss of live managing forests as part of a carbon mitiga- carbon stored in the Earth thereby reduc- tree carbon, turning affected forests into car- tion strategy needs to consider all those ele- ing the flow of fossil fuel–based carbon bon emitters. In the rest of the United ments as an integrated whole across spatial emissions to the atmosphere. and temporal scales. Policies that ignore how States, insect, disease, and storm-related forests fit into the broader economic, envi- conversion of live carbon to dead carbon ronmental, and social framework can fall far US policies can encourage management eventually slows, stops, and sometimes re- short of the possible reductions in carbon of forests for all the carbon and energy ben- verses net sequestration. emissions and lead to counterproductive efits of forests and forest products while sus- Old forests have some of the largest car- mitigation strategies that are environmen- taining ecosystem health and traditional for- bon densities but typically low or near-zero tally and economically unsustainable. Effec- est biomass uses. The scientific information rates of additional carbon sequestration and tive solutions require a wider perspective in this article can be used as the basis for higher probabilities of loss. For example, that consider among many other things, the developing sound forest carbon policies. 85% of the woody biomass–based carbon

Journal of Forestry • October/November 2011 (supplement) S9 storage in ponderosa pine forests in central growth in live-tree inventories (28%), har- forest management approaches to respond Oregon is in stands older than 100 years vested wood products (23%), energy (18%), to climate-related stresses. Some researchers where annual accumulation is slowing and and natural mortality and logging residues believe that seed sources and silvicultural the risks of carbon loss due to wildfire are (31%). These end uses each have unique car- methods must be matched to predict cli- high and often increasing. Regeneration har- bon storage characteristics and trajectories. matic conditions to maintain or increase vest in high-volume old-growth could re- The distribution of total forest growth varies productivity. lease carbon that would not be used for considerably among regions, with the South Recent data on tropical forest cover products or energy. However, these stands producing more products, the North and have significantly lowered the estimates of are found almost exclusively on public lands Pacific Coast harvesting a smaller fraction of net GHG emissions related to tropical de- and are rarely harvested or even actively new growth while still producing consider- forestation overall and suggest a need for a managed in the United States today. able products, and the Rocky Mountain greater focus on deforestation in areas where Soil carbon can have residence times as region having the highest fraction of total carbon-rich peat soils are disturbed. When long as thousands of years, as long as it is growth converting into deadwood. the broad range of feedbacks is considered, deep in the soil profile or associated with Since 1985, annual US wood produc- tropical forests are considered by most ob- minerals. The effect of harvest and replant- tion has stayed roughly constant, at 420 mil- servers to be the most effective forests in 3 ing on soil carbon is difficult to generalize, as lion m , while consumption increased to terms of overall climate benefits provided 3 much depends on the initial soil depth, the 550 million m by 2005. Counting the in- per unit of area or biomass. depth to which soil is sampled, and posthar- creased forest carbon sequestration in the Links between water and carbon flux vest site preparation. The measured effects United States as new global carbon seques- are seen in all forest types but most strongly tend to be slight in the short term, with car- tration overstates the benefits, however, be- in the tropics. The most significant water bon decreases concentrated in the forest cause of the substitution of Canadian for US flux link between forests and the atmosphere floor and near the soil surface and carbon wood products. is the evaporative cooling from tropical for- increases occurring in the deep mineral soil est canopies, which has a positive relation- layers. Whole-tree harvesting for biomass Climate–Forest Interactions ship with cloud formation and rainfall pat- production has little long-term effect on soil With forests covering approximately terns. In semi-arid areas in tropical and carbon stocks if surface soil layers containing 30% of Earth’s land surface and storing temperate regions, research has pointed to a organic material (O horizon) are left on site, about 45% of terrestrial carbon, forests and tradeoff between increased carbon storage in global climate are closely linked in terms of nutrients are managed, and the site is al- new trees and reductions in streamflow lowed to regenerate. Converting agricultural carbon storage and releases, water fluxes available to other plants and animals. and degraded lands to forests or short-rota- from the soil and into the atmosphere, and A significant energy flux related to for- tion woody crops increases aboveground solar energy capture. Estimates of the car- ests at the global level is the drop in the al- carbon stocks as well as soil carbon stocks. bon, water, and energy balances of forests bedo when dark-colored trees expand at the Fuel treatments designed to reduce fire differ, however, depending on the atmo- expense of snow-covered areas with little or hazard and other stand manipulation that spheric model or forest cover and forest in- no tree cover. A lower albedo decreases the promotes resilience by reducing potential ventory model used. fraction of solar energy that is reflected into losses due to insects, diseases, or storms can- Not all the carbon captured by trees the atmosphere. The albedo effect is most not eliminate risk but can reduce the scale of ends up as stored carbon. Approximately important on the northern edge of the bo- tree mortality and associated carbon emis- three-quarters of the carbon fixed by photo- real region; it is measurable but less signifi- sions. The carbon losses from disturbances synthesis is immediately released through accrue over time as the live biomass is con- ecosystem respiration. In forests, about one- cant in temperate regions. verted to dead biomass that slowly releases half of the respiration comes from above- Biomass Use and Feedstock carbon dioxide via enhanced microbial res- ground vegetation and one-half from the piration. forest floor and forest soils. The increase in Issues Including the boreal forests of Alaska forest floor and soil respiration is pro- Feedstock supply depends not just on and the tropical island forests, 53% of the portional to how much woody debris— supply-and-demand curves but also on bio- area of US forests is timberland (i.e., forests whether from natural mortality or logging mass availability; harvesting, delivery, and that are available for periodic harvesting) of residues—is decomposing on site. other costs; landowner objectives; and na- naturally regenerated origin, much of which Temperate forests continue to increase tional, regional, state, and local laws, regula- is managed; 7% is forest plantations; and as carbon sinks even though large quantities tions, and policies. Forest biomass includes 40% is reserved or low-productivity forest. of wood products are removed from these residues from forest stand improvements, The carbon dynamics of each forest type are forests annually. The current rate of carbon timber harvests, hazardous-fuel reduction strongly influenced by the long-term sus- accumulation in temperate forests may de- treatments, forest health restoration proj- tainability of the forests, the types of wood cline, however, if the average age of forests ects, energy wood plantations, and other products that are harvested, and the life- continues to increase. Changing climate similar activities. Regional variations influ- cycle carbon consequences of the various may also adversely impact carbon seques- ence the United States’ potential feedstock products. tration rates. Significant increases in the supply of biomass and ultimately the loca- After accounting for the wood used for shift from live-tree to dead-tree biomass tion of bioenergy facilities. Readily available energy in sawmills and paper mills, the an- from fires and beetles in western North forest biomass supply encompasses woody nual growth of forest carbon is split among America have generated interest in changing biomass by type and US region that is eco-

S10 Journal of Forestry • October/November 2011 (supplement) nomically available based on standard and of the product. At the end of their lives, amount of carbon credits generated for the existing logging configurations. wood products can be reused, recycled, same project can differ dramatically depend- Expanding forest biomass use for either burned for energy, or landfilled. If they ing on the sets of carbon pools allowed and biofuels or energy generation may compete are landfilled, the carbon contained within the baseline approach employed. with traditional forest products, but it may them can be stored for a long period of time, Protocols for forestry offset projects also produce benefits through competition but there can also be a substantial GHG usually include the following elements: eli- and market efficiency. Changes in feedstock cost because of methane emissions, particu- gibility, carbon sequestration calculation use are controversial and a point of conten- larly from paper decomposition. This sug- procedures, baseline requirements, carbon tion for competing industries (paper and gests that incentives should be high to reuse pools, crediting period, leakage, perma- pulp versus bioenergy), environmental and paper and wood, recycle it, or burn it to re- nence, and reversals. The costs associated other nongovernmental organizations (who cover at least its heating value. with establishing and maintaining forestry are concerned about industrial-scale bio- A sustainably managed forest can pro- offset projects depend largely on the pro- mass production), private landowners (who duce a continual flow of wood products and tocols’ specifics. Because protocols differ see opportunities for additional revenue biomass for energy while at the same time greatly in their requirements for monitoring streams), and public land managers (who maintaining or increasing carbon stocks. and verification, carbon measurement, and need markets for low-quality material re- Determining the effects of forest harvesting third-party certification, the transaction moved from overgrown forests). for wood products or bioenergy production costs per hectare also vary substantially, by as Biomass feedstock supply will be af- requires a landscape-level analysis over time. much as a factor of five. fected by landowners’ preferences based on For instance, in harvesting woody biomass Forestry offset projects generally can be price, investment-backed expectations, and for use in generating energy, carbon is re- classified as afforestation, reforestation, for- environmental considerations, all of which moved from the forest, reducing forest car- est management, forest conservation, or for- are affected by government energy and envi- bon stocks, and that carbon is liberated as est preservation. The estimates of net cli- ronmental policies. Short-rotation woody biomass is converted to energy. However, as mate benefits from forest management, crops, such as shrub willow, hybrid poplar, long as harvests and mortality do not exceed conservation, or preservation projects de- southern pine, and eucalyptus, have the po- net growth across the forest, carbon stocks pend largely on the assumptions about the tential to increase woody biomass feedstocks remain stable or increase through time and carbon storage and substitution benefits of from both forestlands and converted agri- the total carbon sequestration potential of wood products; this is less true for afforesta- cultural lands. the forests is maintained. In addition, the tion and reforestation projects. For an offset products removed from the forest provide a project to have any effect on net GHG emis- Energy, Products, and long-term carbon benefit equal to the sions to the atmosphere, the net amount of Substitution avoided emissions from fossil fuels less any carbon sequestered must be additional to fossil energy used to harvest and transport what would have occurred anyway. For for- Forests store carbon, and so do wood the biomass feedstock. est projects, additionality is relatively easy to products. Evaluation of carbon flows shows Sustainable forest management helps establish when new trees are planted and that conversion of wood to useful products ensure a neutral carbon cycle on the forest- maintained but considerably more difficult can significantly reduce overall societal car- land base. Carbon storage in wood products to demonstrate when based on what did not bon emissions. To arrive at a cogent picture and wood use for energy from material har- or will not happen (e.g., “I was going to har- of the overall forest sector effect on atmo- vested from that land base is an additional vest in 10 years but instead will wait 30 spheric carbon, we need to understand the carbon benefit beyond the forest. years”). If forest carbon credits are used to material and energy flows as inputs and out- permanently offset industrial emissions, the puts within well-defined system boundaries. Forest Carbon Policies forest project must show permanence by en- Then, we need to integrate the effects across At the national level, increasing net car- suring that initial emissions are balanced by system boundaries to understand the many bon sequestration rates in forests, using an equivalent amount of new carbon storage ways in which substitution of harvested wood products rather than fossil fuel–inten- over time. However, strict project-level wood products for fossil fuels and fossil fuel– sive products, and using forest residues for guarantees or insurance increase the cost of intensive products can offset the flow of car- energy will reduce GHG emissions. How- forest carbon credits. Also, US forestry proj- bon dioxide from fossil carbon reserves to ever, project-based accounting rules that ig- ects that increase in-forest carbon sequestra- the atmosphere. nore or undercount nonproject benefits and tion through a short-term reduction in har- Forest products have lower embodied risks can result in project-based conclusions vests may have national market leakage rates energy (the amount of energy it takes to that differ from a more comprehensive na- that approach 100% if harvests from non- make products) than comparable building tional or international accounting. project forests meet consumer demand. products, so there is a substitution effect Forestry offset protocols have been cre- Modeled benefits of forest carbon offset when wood is used in place of steel, alumi- ated to serve different purposes. Some were projects are highly variable and dependent num, concrete, or plastic. That substitution created as part of cap-and-trade programs, on assumptions, including estimates of for- effect varies by use and comparable product either mandatory or voluntary, or as part of est carbon flux. Determining with precision but on average, every 1 tonne (t) of wood emissions reduction schemes. Others were whether a threshold flux for a given area has used removes 2.1 t of carbon from the atmo- developed independently but have been ad- been or will be achieved is difficult with the sphere. opted by one or more programs. Although technology available today. Wood products store carbon for the life the concept of offsets is the same, the The measurement challenges and rela-

Journal of Forestry • October/November 2011 (supplement) S11 tively high transaction costs inherent in for- bon without providing the carbon benefits one-half or less the total energy and one- est carbon offset systems motivate consider- available through product and energy substi- fourth to one-fifth the fossil energy. ation of other policies that can promote tution. Conserving forests for recreational, aes- climate benefits from forests without requir- thetic, and wildlife habitat goals has been a ing project-specific accounting. For exam- 2. Recognize that Substantial Quanti- strong policy driver in the United States over ple, market prices for building and energy ties of Carbon Are Stored in Wood the past few decades, especially in the Pacific products that reflect emissions, economic Products for Long Periods of Time Wood is one-half carbon by weight, Coast and Northeast regions. Evidence of incentives for treeplanting, and credible in- increasing losses to disturbances that are formation disclosure on the relative climate and it lasts a long time in service—often for a long time after being retired from service. not captured in forest growth modeling and impacts of different products could prove decreasing rates of carbon accumulation in more effective at a national scale. Substantial volumes of wood go into construction products and structures: even maturing forests suggests that a strong con- Integrating Forests into a during the midst of the recent “Great Reces- servation-oriented strategy may not always produce significant global climate benefits. Rational Policy Framework sion” (2007–2009), US housing starts exceeded 440,000 annually. Additional wood The climate benefits of active forest manage- Forests are an integral component of is used for furniture and other products, ment are most apparent when the substitu- the global carbon cycle and may change in which at the end of their useful lives may be tion benefits that occur in the consumer sec- response to climate change. US forest poli- converted to energy. Paper may go into tor are included. As we move forward with cies can foster changes in forest management long-term use (e.g., books) or be recovered policy discussions regarding the many posi- that will provide measurable reductions in from the waste stream for energy productive roles of US forests at local, national, and carbon emissions over time while maintain- tion. Other wood—construction debris, global scales, it will be imperative that ob- ing forests for environmental and societal yard waste, and unrecycled paper—winds jective, science-based analysis and interpre- benefits, such as timber and nontimber for- up in landfills, where it often deteriorates tations are used and that particularly close est products, vibrant rural communities, more slowly than is generally assumed. In attention is paid to the assumptions under- clean water, and wildlife habitat. Policies total, the rate of carbon accumulation from lying the analyses. founded on three tenets reflecting the stocks wood products in use and in landfills was US policymakers should take to heart and flows of woody biomass can ensure that about 88 million tonnes of carbon dioxide the finding of the Intergovernmental Panel US forests will produce sustainable carbon, on Climate Change (IPCC) in its Fourth equivalents (CO2e) in 2008, about 12% of and environmental and societal benefits. the rate of sequestration in forests. Assessment Report when it concluded that “In the long-term, a sustainable forest man- 1. Keep Forests as Forests and Man- 3. The Substitution Effect Is Real, Irre- agement strategy aimed at maintaining or age Appropriate Forests for Carbon versible, and Cumulative increasing forest carbon stocks, while pro- For more than 70 continuous years, US Compared with steel, aluminum, con- ducing an annual sustained yield of timber, forest cover has increased and net growth has crete, or plastic products, considerably less fibre or energy from the forest, will generate exceeded removals and mortality. Therefore, energy, and vastly less fossil fuel–derived en- the largest sustained mitigation benefit” carbon storage is increasing in the United ergy, is required to make wood products. (IPCC 2007a, p. 543). A rational energy and States. In some forests (e.g., old-growth), The low embodied energy of wood building environmental policy framework must be other considerations and other benefits will products, structures, furniture, cabinets, and based on the premise that atmospheric outweigh carbon benefits. However, forests other products has been well documented GHG levels are increasing primarily because will change with or without management, through life-cycle assessments. Not only is of the addition of geologic fossil fuel–based and choosing not to manage has its own car- the quantity of energy used in manufactur- carbon into the carbon cycle. Forest carbon bon consequences. Young, healthy forests ing wood products low compared with other policy that builds on the scientific informa- are carbon sinks. As forests mature, they materials, but the quantity of fossil energy is tion summarized in this article can be an generally become carbon-cycle neutral or comparatively very low: one-half to two- important part of a comprehensive energy even carbon emission sources because net thirds of the energy used by the North policy that promotes energy independence primary productivity declines and the decay American wood products industry is bioen- and delivers carbon benefits while providing of trees killed by natural disturbances— ergy. For instance, compared with steel essential environmental and social benefits, windstorms, fire, ice storms, hurricanes, and framing with an average recycled content, including clean water, wildlife habitat, and insect and disease infestations—emits car- the manufacture of wood framing requires recreation.

S12 Journal of Forestry • October/November 2011 (supplement) section 1

Introduction

he United States needs many differ- possible reductions in carbon emissions no net release of carbon as long as overall ent types of forests: some managed and lead to counterproductive mitigation forest inventories are stable or increasing T for wood products plus other bene- strategies that are environmentally and eco- (as is the case with US forests). fits and some managed for nonconsumptive nomically unsustainable. Effective solutions 3. Forest products used in place of energy- uses. Management decisions must account require a wider perspective that considers, intensive materials, such as metals, con- for local conditions; landowners’ objectives; among many other things, the role of forests crete, and plastic, (a) reduce carbon emis- and a broad set of environmental, economic, as a source of products for society and the sions (because forest products require less and societal values. This article considers effects of those products on GHG concen- fossil fuel–based energy to produce), (b) how various forest and wood use strategies trations. store carbon (for a length of time based can reduce accumulation of greenhouse on products’ use and disposal); and (c) gases (GHG) in the atmosphere. Forest Carbon Policies provide biomass residuals (i.e., waste wood) that can be substituted for fossil Carbon Framework US environmental and energy policies fuels to produce energy. need to be linked or at least be based on 4. Fossil fuel–produced energy releases car- A simplified representation of the mutual recognition and should be based on global carbon system shows that carbon is bon into the atmosphere that has resided four basic premises grounded in the science in the Earth for millions of years; forest stored in various pools (stocks) with dy- summarized in this article: namic flows (fluxes) between the pools (Fig- biomass–based energy uses far less of the carbon stored in Earth thereby reducing ure 1-1). The oceans, and lands, both for- 1. Sustainably managed forests can provide ested and nonforested, emit carbon to and the flow of fossil fuel–based carbon emis- carbon storage and substitution benefits sions to the atmosphere. absorb carbon from the atmosphere in a while delivering a range of environmen- two-way flow. In contrast, carbon removed tal and social benefits, such as timber and US policies can encourage management from fossil fuel reserves acts as a one-way biomass resources, clean water, wildlife of forests for all the carbon and energy ben- flow because regardless of whether emissions habitat, and recreation. efits of forests and forest products while from fossil fuel combustion are ultimately 2. Energy produced from forest biomass re- sustaining ecosystem health and traditional taken up by land, ocean, or forests, they are turns to the atmosphere carbon that forest biomass users. The scientific informa- not returned to fossil fuel reserves on any- plants absorbed relatively recently from tion in this article can be used as the basis for thing less than a geologic timescale. Al- the atmosphere; it essentially results in developing sound forest carbon policies. though there are many uncertainties in measuring carbon stocks and flows globally, the objective of reducing global GHGs suggests the importance of increasing carbon storage in pools other than the atmosphere. Growing more forests and keeping forests as forests are only part of the solution because focusing solely on the sequestration benefits of the forests misses the important (and substantial) carbon storage and substitution GHG benefits of harvested forest products. An assessment of forest management as part of a carbon mitigation strategy needs to consider all of those elements as an integrated whole across spatial and temporal scales. Policies that ignore how forests fit into the broader economic, environmental, Figure 1–1. Major global carbon pools, their interactions, and forest and fossil fuel and social framework can fall far short of products. (Source: Adapted from Lippke et al. 2011.)

Journal of Forestry • October/November 2011 (supplement) S13 section 2

Forest Carbon Stocks and Flows

S forests were in carbon balance gion. Across the whole United States, car- subject to decay and heterotrophic (micro- with the atmosphere (emissions bon removed from the atmosphere by forest bial) respiration. In a study of disturbance U approximately equal to sequestra- growth or stored in harvested wood prod- types in evergreen forests in seven disparate tion) from the beginning of Euro-American ucts is equal to 12–19% of fossil fuel emis- regions of the United States, Thornton et al. settlement to 1800. Subsequently, forests sions (Ryan et al. 2010, EPA 2010). (2002) found that peak emissions related to were cleared for agriculture and construc- disturbance occurred 2 years after the distur- tion, resulting in significant emissions of Forest Carbon Trajectories bance, and that emissions could exceed se- carbon until 1950. These same forests are Forest carbon constitutes about one- questration for up to 16 years—until the now significant carbon sinks (Pacala et al. half of the bone-dry forest biomass. When live trees grew to a size at which their absorp- 2001) because of forest regrowth in areas we consider the temporal dynamics of car- tion of carbon exceeded the onsite losses where agriculture was abandoned (Birdsey et bon in the forest, therefore, it can be helpful from decomposition of the predisturbance al. 2006), fire suppression in western forests, to think of how forest biomass fluctuates forest. If an old-growth stand, in which increased productivity of planted forests, over time at the stand level. In forest types disturbance or harvest leaves behind high and forest management activity. These fac- that are predominantly even-aged, either be- volumes of large-diameter deadwood, the tors were responsible for a carbon flux as cause of management choice or natural dis- period in which emissions exceed sequestra- large as Ϫ390 teragrams (Tg; trillion grams)/ turbance regimes, a stand is initiated (via tion could be as long as 20–30 years (Har- year as recently as the 1990s (Houghton et al. afforestation or reforestation after a fire, harmon and Marks 2002). Assuming sufficient 2000). (By convention, carbon sequestra- vest, or other stand-replacing disturbance), stocking, a stand of pole-sized trees is well tion is represented as negative flux and car- grows (using photosynthesis to extract car- positioned to accumulate woody biomass bon emissions as positive flux.) bon from the atmosphere and distribute it to carbon at an increasing rate for several de- US forests today are known to function leaves, stem, and roots), and ultimately dies cades, barring excessive disturbance, but at as a substantial carbon store, with woody (via harvest or other stand-replacing distur- some point, growth decelerates. biomass carbon stocks averaging nearly 58 bance or conversion to a nonforestland use). Because carbon sequestration rates peak Mg (million grams)/ha, estimated via re- Management activities, such as thinning, in the first 100–150 years in most even-aged mote sensing (Myneni et al. 2001), and fertilization, and hazardous fuel removal, stands as tree mortality losses increase, older nearly 84 Mg/ha, estimated via inventory may occur along the way. Where stand- stands tend to be weak sinks at best. None- statistics (US Environmental Protection replacing disturbance is rare or management theless, analysis of forest inventory plots Agency [EPA] 2010). Carbon flux reported emphasizes selection harvest, the birth and shows that in rare cases (e.g., very wet forests for the entire forested area of the United death of trees in a stand is continuous or on Washington’s Olympic Peninsula), for- States ranges from Ϫ141 (Myneni et al. episodic, resulting in a stand-level trajectory est carbon stores may continue to increase 2001) to Ϫ183 (Birdsey et al. 2000) to –192 of forest carbon without pronounced peaks for as long as 800 years. A few old-growth (US EPA 2010) Tg of C/year, not account- and valleys. In such forests, gross primary forests can achieve truly massive (more than ing for storage in harvested wood products. productivity and allocation of forest car- 1,100-Mg of C/ha) carbon stocks (Smith- Both stocks and flux vary greatly by region, bon among live and dead trees, understory wick et al. 2002), and researchers are increas- forest type, site class, owner group, and re- shrub and herbaceous vegetation, forest ingly documenting that some old-growth serve status. For example, inventoried floor, litter and soils are ever changing. Un- forests can continue to have greater seques- aboveground live and deadwood average derstanding these dynamics and how alloca- tration than respiration as long as they are carbon stocks in California range from 13 tions change with stand age, density, and not affected by stand-terminating distur- Mg/ha for pinyon-juniper to 360 Mg/ha for management is essential to identifying op- bances. Luyssaert et al. (2008) also found redwood (Christensen et al. 2008). Carbon portunities to manage forests to increase positive net ecosystem productivity in for- flux on highly productive national forest their capacity to remove carbon dioxide ests as old as 800 years in the boreal region, lands in California averages Ϫ1.25 Mg/ha but they noted that many stands had experi- (CO2) from the atmosphere (Litton et al. per year versus 0 Mg/ha per year for low- 2004). enced, and will continue to experience, productivity (nontimberland) forests (Fried stand-terminating disturbances. 2010). Han et al. (2007) report a sink size Stand-Scale Trajectories Growth decline is ultimately inevitable, for an 11-state region in the southern A newly regenerating forest behaves as a however, as gross primary productivity is re- United States as Ϫ130 Tg of C/year and net carbon source to the atmosphere because duced by nutrient and other resource limi- assert that this is sufficient to capture 23% of the above- and belowground remains of tations and carbon allocation shifts from greenhouse gas (GHG) emissions in that re- woody plants in the antecedent forest are wood production to respiration (Ryan et al.

S14 Journal of Forestry • October/November 2011 (supplement) 2004). Ponderosa pine forests older than coarse woody debris and mineral soil; the bon—so much, in fact, that it may take de- 190 years in central Oregon remain weak mature lodgepole pine forests elsewhere in cades before the new stand establishes carbon sinks, with a mean flux of Ϫ0.35 Mg the park have 64% of their carbon in live greater net uptake of carbon (after account- of C/ha per year (Law et al. 2003). From a trees (Litton et al. 2004). The carbon lost in ing for storage in wood products, slash dis- landscape perspective, 85% of the woody the 1988 fires may not be recovered for 230 posal, emissions from deadwood and other biomass-based carbon storage in ponderosa years (Kashian et al. 2006). In this and less harvest-killed vegetation, and soil carbon pine forests in this area is found in stands extreme cases, the carbon implications of emissions) than if the old-growth had been older than 100 years and faces a significant disturbance are greatly influenced by the left alone (Janisch and Harmon 2002). risk of carbon loss from wildfire. Dimin- amount of the previous stand used in har- However, such stands, which are found al- ished sink strength at even younger ages has vested wood products and bioenergy; in most exclusively on public lands, are rarely been widely documented. In Swiss alpine the Yellowstone case, this was zero. Late- harvested or even actively managed in the forests, storage capacity was found to peak at successional forests, like the federally pro- United States today, and in any case, are un- 100 years, after which forests were net emit- tected wilderness and parks in the West, likely to be considered candidates for bio- ters of carbon (Schmid et al. 2006). An Aus- hold tremendous carbon stores but have low energy feedstocks because their value as en- trian study that also accounted for wood rates of carbon accumulation compared ergy feedstock is low compared with the products and bioenergy offsets found that with younger forests. The carbon stores of high social values placed on old-growth for- overall carbon storage was greatest in un- very large forest areas—those consisting of ests. Where catastrophic losses are likely managed stands over a 100-year horizon, thousands of stands spanning a broad (e.g., in drier forest types where fire or in- but that the effective storage could well be range of age and successional development sects drive shorter disturbance intervals), the much less because the standing carbon was classes—have achieved an approximately carbon calculus is different. In this case, vulnerable to unforeseen disturbances steady-state plateau (Harmon et al. 2001). management that involves periodic harvest (Seidl et al. 2007). The Tongass National However, this “carbon plateau” may trend provides a range of societal benefits. Regen- Forest, where fire is unlikely, holds 8% of up or down with changes in growth rates erated young stands continue to sequester the forest carbon in the United States but and natural and human disturbance fre- new forest carbon, and products derived is approaching a state of no additional car- quency and magnitude, all of which may re- from the harvested wood store carbon for bon sequestration because carbon emissions sult from climate change (Latta et al. 2010, various lengths of time and provide substi- via microbial respiration will soon equal Smithwick et al. 2007). tution benefits that show up in national newly sequestered carbon via photosynthesis GHG accounts in lower emissions from fos- (Leighty et al. 2006). Management and Forest sil fuel burning. At some point, reduction of carbon Carbon Capture Forests can be managed to maximize stocks in any individual stand is also inevita- carbon sequestration. Even-aged rotations Eventually, all trees die, and when they ble. Carbon may be emitted through natural synchronized to culmination of mean an- do, their carbon moves quickly (e.g., fire, disturbance or harvesting. Typically, a large nual increment* lengthen the period during windthrow, or harvest) or slowly (e.g., insect fraction of forest carbon from a harvested which current annual increment (1 year’s attack or disease infestation) into other pools stand is sequestered in long-lived forest addition to the live-tree carbon pool) ex- (e.g., deadwood, soil, products, or atmo- products or converted to bioenergy. Al- ceeds the maximum MAI. Across an owner- sphere). The process of forest renewal and though carbon emissions from producing ship, shorter rotations may reduce maxi- tree growth, competition, aging, and, even- bioenergy may be the same as emissions mum sequestration on currently managed tually, death is ongoing. Environmentally from natural disturbance, the latter achieves sites but can generate additional discounted sensitive use of forest mortality offers the op- no carbon benefit. An accurate portrayal of net revenue that could be invested to in- portunity to capture some permanent car- forest carbon and the carbon benefits and crease growth in other forests. Rotations bon benefits via long-term storage in prod- costs of any harvested products requires longer than maximum MAI reduce the ca- looking at a large number of forests stands of ucts and/or substitution for fossil fuel pacity for long-term storage in harvested different ages, the amount of carbon seques- energy. Depending on other objectives, wood products and, at least in some systems, tered in products, and the likely effects of these benefits can be captured using a wide increase the risk of catastrophic carbon loss. disturbances. variety of management-driven removals, in- Reducing stocks in forests managed for cluding sanitation, mechanical fuel treat- commercial products may reduce the finan- Forest-Scale Trajectories ment, thinning, selection harvest, regenera- cial and carbon risks of losses to episodic Whereas forest carbon dynamics at tion harvest, and salvage logging, albeit with disturbances, such as wildfires or severe stand scale are driven by growth, harvest, varying implications for economic feasibility storms, and potentially increase the average and mortality, at the forest scale they are af- and residual stand conditions. Such benefits value of the products produced; increasing fected at least as much by the distribution of do not accrue when dead and dying trees are stocks may increase the rate of carbon accu- forest area by age class or successional state left in the woods to emit carbon via hetero- mulation but also increase loss risk. Al- and management regime. More than one- trophic respiration, and when capture op- though any kind of harvest releases at least third of the forest area of Yellowstone Park, portunities are missed, there are no second e.g., is of a single age class, born after the fires chances. The timing of removals, however, * MAI; i.e., the point at which average annual of 1988. Now undergoing a period of rapid can be important. woody carbon accumulation, calculated as total growth and accumulating carbon, these Regeneration harvest in a high-volume carbon divided by stand age, peaks and begins to forests still have 91–99% of their carbon in old-growth stand releases a great deal of car- fall.

Journal of Forestry • October/November 2011 (supplement) S15 Table 2-1. Carbon flux in the US forestry As currently reported, estimates for all other low1mindepth (Jobbagy and Jackson sector in 2008, excluding energy sector forest pools are derived from models, in 2000), where it has been found to have very and product substitution benefits. which their assumptions may lead to inaccu- long residence times (thousands of years; racies. For example, deadwood is modeled as Trumbore et al. 1995). 2008 fluxa a fraction of live wood, and soil carbon den- Litterfall and root turnover (rhizodepo- Percentage sity is assigned by forest type. Although de- sition) are the major inputs of carbon to soil b Carbon pool Tg CO2e of total finitive conclusions are elusive because of carbon pools and are closely related to net changes in inventory measurements and primary productivity (Schlesinger 1997). Forest Ϫ704 89c Root inputs of carbon account for 56–71% Aboveground biomass Ϫ397 50 protocols since 1990, the US forest carbon Belowground biomass Ϫ79 10 sink has been reported as weakening due to of mineral soil carbon (Rasse et al. 2005). Deadwood Ϫ26 3 increasing forest age and time since farm- Most carbon entering soil pools in forested Ϫ Litter 56 7 land abandonment, climate variability, and systems decomposes and is emitted through Soil organic carbon Ϫ146 18 Harvested wood Ϫ88 11 increasing frequency and severity of natural heterotrophic soil respiration (Hanson et al. Products in use Ϫ24 3 disturbances (some resulting from many 2000, Subke et al. 2006). An increase in this Wood in landfills Ϫ64 8 years of fire suppression). Moreover, it ap- heterotrophic soil respiration caused by Total net flux Ϫ792 100 pears that climate change will increase the global warming may be a positive feedback frequency of disturbance in forest ecosys- mechanism of climate change (Raich and a Carbon sequestration is negative flux; carbon emissions is positive flux. tems (e.g., Hurtt et al. 2002, Dore et al. Schlesinger 1992). Stabilization of carbon b Tg CO2e, teragrams of carbon dioxide equivalent; to obtain 2008, Pan et al. 2008). entering the soil system depends on the car- teragrams of C from Tg CO2e, divide the latter by 3.667. Source: US EPA (2010). bon content of the soil horizon it enters. c Percentages of forest carbon pool do not add up to 89 due to Carbon Trajectories in Forest Soils Carbon entering a carbon-rich or carbon- rounding. Soil carbon, both in litter layers and as- saturated surface horizon may accumulate at some carbon to the atmosphere, thinning sociated with soil minerals, occurs in a het- a constant rate but have a very short resi- and selection harvests typically have a lower erogeneous mix of organic materials dence time. On the other hand, carbon en- emissions density per unit area because they (Hedges et al. 2000). Soil carbon is the larg- tering a carbon-poor soil horizon has more produce less slash and residual organic mat- est actively cycled terrestrial carbon pool potential to be stabilized in a mineral-asso- ter (e.g., down wood and dead roots). Com- (Schlesinger 1997, Hedges et al. 2000, Job- ciated recalcitrant pool because of the larger pared with regeneration harvests, thinning bagy and Jackson 2000) and can have resi- proportion of reactive mineral surface area. and selection also result in a far shorter delay dence times of hundreds to thousands of Because surface soil horizons in forest soils before net carbon uptake is restored, because years (Gaudinski et al. 2000, Trumbore are near saturation, an increase in carbon the residual stand maintains greater carbon 2000). These attributes imply that soils may stores here is unlikely. Mineral soil at depth sequestration capacity than does a clearcut. be an attractive pool to sequester carbon for (e.g., more than 50 cm) has much lower car- Even-aged harvests have a somewhat longer- long periods (Oldenburg et al. 2008). Forest bon concentrations and therefore may have lasting effect on net carbon flux because management and disturbances affect soil the capacity to stabilize carbon; however, in- there is no residual stand to sequester car- carbon stocks through changes in carbon puts of carbon to this depth are also low. bon, and seedlings must grow for several fluxes and carbon quality, and the magni- Harvesting and thinning operations al- years before they become a significant car- tude and direction of these changes tend to ter soil carbon cycling by cutting the supply bon sink. be highly variable by region and situation. of root and litter inputs, disturbing the soil The simplest conceptual model of soil surface, and changing temperature and Estimates of US Carbon Flux by Pool carbon is that of two pools of labile and re- moisture regimes, all of which tend to in- Table 2-1 shows the estimated US for- calcitrant carbon that have short and long crease heterotrophic respiration rates; how- estry sector annual flux in teragrams of car- residence times, respectively. Generally, the ever, they also move some forest floor carbon bon dioxide equivalent (CO2e) for 2008, the most labile carbon is organic (e.g., O hori- into deeper, mineral soil layers. A few meta- most current year available (US EPA 2010), zons and belowground particulate organic analyses and review articles conclude that as reported under international carbon matter) and represents about 1–12% of for- the net effect of harvest is a reduction in soil protocols. This framework calculates net est soil carbon (Schlesinger 1997, Fisher et carbon, with forest and soil type determin- changes between consecutive, annual esti- al. 2000, Sollins et al. 2006). Mineral-asso- ing the magnitude of carbon loss (Johnson mates for five forest pools and two harvested ciated carbon represents more than 90% of and Curtis 2001, Jandl et al. 2007, Nave et wood pools. Note that only one-half of the all soil carbon and has the longest residence al. 2010). Nave et al. (2010) reported an 8% flux is estimated to occur in the above- time (i.e., oldest 14C age) (Fisher et al. 2000, average reduction in soil carbon stocks after ground, live-tree pool—the pool that is Gaudinski et al. 2000, Jobbagy and Jackson harvesting over all forest and soil types stud- most commonly considered in carbon ac- 2000). Mineral-associated carbon is pro- ied. However, most of the studies covered counting analyses. Of the aboveground for- tected from mineralization through its sampled only the top 20 cm of soil, or even est carbon, current measurement procedures chemical stabilization with mineral surfaces just the forest floor, so these losses are pri- are more accurate for the boles of trees of the (particularly reactive minerals such as iron marily the result of a reduction in litter layer species and sizes that have typically been oxides) (Kleber et al. 2005, Mikutta et al. mass and organic matter inputs from grow- used to produce products, and considerably 2006) and physical protection within soil ing trees; they may also reflect the sampling less accurate for noncommercial species and aggregates (Six et al. 2002). Additionally, challenges of accurately tracking forest floor for the branches, tops, and roots of all trees. 36–41% of all soil carbon can be found be- carbon over time (Federer 1982, Yanai et al.

S16 Journal of Forestry • October/November 2011 (supplement) 2003). Harvesting either has no effect on Gifford 2002, Post and Kwon 2000, Sartori 2011). In the West, where public forests mineral soil carbon or leads to increases et al. 2006). predominate, the average stand age is 90 (Slesak et al. 2011). Harrison et al. (2011) Fire can be a major cause of carbon loss years; for private forests in the East, it is 47 report that for a variety of ecosystems and from forests, but the magnitude of loss de- years. In Canada, the average stand age for treatments, valid estimation of changes in pends on fire severity. Low-severity wildfires managed forests is 92 years, and in Europe it ecosystem carbon was not even possible and prescribed fires have little effect on soil is 48 years (Bottcher et al. 2008). US west- without sampling soil deeper than 20 cm. carbon and may even increase mineral soil ern forests are similar to those of western Even whole-tree harvesting for biomass pro- carbon through deposition and mixing of Canada (Kurz et al. 2008a, Stinson et al. duction may have little long-term effects on partially burned or residual organic matter 2011) in their high carbon inventories as soil carbon stocks if O horizons are left into the surface mineral soil (Johnson and well as current high losses to mortality from undisturbed and nutrients are managed Curtis 2001, Hatten et al. 2005, 2008). fires and insects. The younger European for- (Powers et al. 2005). Forest thinning and Conversely, high-severity wildfire decreases ests are estimated to have much higher net competition control have a much smaller soil carbon stocks by 10–60% (Baird et al. carbon sequestration rates and much lower disturbance on soil characteristics and there- 1999, Bormann et al. 2008, Hatten et al. losses to mortality (Luyssaert et al. 2010). fore affect soil carbon stocks less. In addi- 2008). Recovery rates after moderate- to The fraction of total growth in merchant- tion, by reducing the likelihood of stand- high-severity fire may be similar to a post- able volume that ends up as mortality is now replacing wildfire and fire severity at the soil harvest scenario, provided soil productivity nearly twice as high on national forests (0.33 surface, thinning and fuel reduction treat- is not damaged. Although high-severity in the East and 0.36 in the West) as on tim- ments may reduce future losses of soil car- wildfire can release significant amounts of berlands outside the national forests (0.19 in bon. carbon from soil pools, the loss can be re- the East and 0.22 in the West; Smith et al. Forest fertilization may increase or de- duced through well-designed fuel reduction 2009). Thus, management that anticipates crease soil carbon stores by increasing net programs based on mechanical thinning and disturbance is a more compelling idea for ϩ primary production ( ), shifting produc- prescribed fire. western forests than for forests elsewhere. If tion to aboveground vegetation components carbon values rise and more efficient recov- Ϫ Given the variable properties of soils, ( ), increasing soil carbon mineralization determining soil carbon stores is more ex- ery technologies develop, natural distur- (Ϫ), and depressing some enzyme activity bances may be seen as opportunities to cap- ϩ pensive (many samples are required) than ( ) (Jandl et al. 2007, Van Miegroet and inventory-based accounting for above- ture carbon benefits via bioenergy from dead Jandl 2007). Effects of forest fertilization on ground, live-tree carbon stores. The high trees that would otherwise emit carbon with soil carbon have been found to be site-spe- variability of soils and inability to take re- no compensating benefits. Understanding cific, but most studies show an increase in peated measures on exactly the same soil the disturbance processes that drive mor- soil carbon stock (Johnson and Curtis make accounting for soil carbon flux over tality and the fate of the dead biomass— 2001). However, fertilization of forests has time even more challenging. Many research- whether it is left in the forest to emit carbon been linked to increased soil emissions of ers have developed sampling protocols over time or collected and used—is a signif- nitrous oxide (N O, a GHG 300 times 2 for soil carbon stores (e.g., Shaw et al. 2008) icant but often overlooked component of stronger than CO ), so this must be factored 2 or the effects of different treatments (e.g., forest carbon dynamics. in when selecting the best management Homann et al. 2001). The magnitude and strategy to mitigate GHG concentrations Fire spatial dependence of soil variability differ (Matson et al. 1992, Castro et al. 1994). The Increased reliance on in-forest carbon among soil types, so a one-size-fits-all ap- production of fertilizer itself also results in storage usually increases carbon emissions carbon emissions because the production proach to soil sampling does not work (Ay- when fire does occur (Hurteau et al. 2008). processes are energy intensive. res et al. 2010). The Forest Inventory and In the West, fire poses the greatest risk of The influence of short-rotation woody Analysis (FIA) (US Forest Service 2011) forest carbon emissions, which are very dif- crops and afforestation on soil carbon stocks program of the US Forest Service collects ficult to quantify because of spatial and tem- appears to depend primarily on previous soil carbon data to a depth of 20 cm across poral heterogeneity: extreme interannual land use, management practices, and soil the United States on phase 3 plots (one per variability has stymied efforts to determine characteristics (Tolbert et al. 1997, 2002, 96,000 ac). This sampling intensity and lim- even the existence of a trend in emissions Guo and Gifford 2002, Post and Kwon ited sampling depth are insufficient to ac- (Liu et al. 2005). Over the long term, assum- 2000, Sartori et al. 2006). Conversion of ag- count for soil carbon across the United ing no trend in fire return intervals, emis- ricultural and degraded lands to forest or States; however, it may help in refining a sions from fires are balanced against carbon short-rotation woody crops is likely to in- sampling system that characterizes soils for a sequestration by the growing forest. On crease soil carbon stocks. Lands used for pe- given region, forest type, and soil type to timescales relevant to forest carbon offsets, rennial crops or pasture typically have higher support a targeted soil carbon inventory pro- fires can release truly massive quantities of carbon concentrations than annually tilled gram. carbon (averaging 293 Tg of C/year in lands, so afforestation may or may not in- 2002–2006, a period of high fire activity), crease soil carbon stocks. Depending on Carbon Flux from Forest adding significant uncertainty to projections the aforementioned factors, short-rotation Disturbances of likely reductions in carbon emissions woody crops may increase soil carbon up to As the average age of trees in forests in- (Wiedinmyer and Neff 2007). In part be- 0–1.6 Mg/ha per year for decades before the creases, both carbon inventories and carbon cause of a century of fire suppression (Agee soil reaches a new equilibrium (Guo and losses to mortality increase (Stinson et al. and Skinner 2005), combined with climatic

Journal of Forestry • October/November 2011 (supplement) S17 factors (McKenzie et al. 2004, 2008, Littell the forests been thinned before the fire, car- Some exotic invasive pests may prevent pre- et al. 2009b), fire is now the dominant dis- bon emissions could have been significantly infestation tree species from becoming rees- turbance agent in most of the West and is reduced. Stephens et al. (2009) accounted tablished, essentially changing the capacity important to consider in virtually every for- for storage in harvested wood products and of a site to store carbon unless alternative est management strategy. Even in wet forests documented emissions from prescribed fire, species with equivalent growth potential are along the Pacific Coast, catastrophic fires mechanical treatment, and a combination of available. Given the cost of fighting inva- have occurred (e.g., the Tillamook Fire in both, with and without a subsequent fire. sions and infestations, managing forests for Oregon’s Coast Range). Relative to the control, mechanical treat- resilience—such as by encouraging species Intense, stand-replacing fires in heavily ment produced less emissions for almost any diversity and managing stand density—may stocked stands can be so severe that substan- plausible assumption of fire probability, and be the most feasible approach. tial soil carbon stores are lost and soil struc- the other options produced less emissions as Insect infestations can heighten the ture and nutrient capital are destroyed, de- the likelihood of fire increased (they resulted risks of severe crown fire (and thus the po- laying regeneration and/or leading to slower in much greater treatment emissions but tential for large emissions of carbon from the regrowth. Treatments that reduce ladder fu- much less posttreatment wildfire emissions). live-tree pool) not because they create dead- els and understory vegetation in general are In some cases, frequent fuel treatments wood but because the resulting change in frequently recommended to reduce fire se- (thinning combined with prescribed fire) stand structure tends to promote ladder fuels verity and the probability of crown fire have been known to reduce site quality (Bigler et al. 2005, Lynch et al. 2006). De- (Brown et al. 2004, Agee and Skinner (Gough et al. 2007). Over the past 10 years, creased susceptibility to surface fire after 2005). Numerous studies have attempted to a comprehensive literature on fuel treat- spruce beetle infestation (Kulakowski et al. assess various combinations of thinning, ments (e.g., Graham et al. 2009, Cathcart et 2003) is possibly caused by increased forest prescribed fire, and understory and down al. 2010, Reinhardt et al. 2010) has specifi- floor moisture. The prodigious amounts of wood removal for their capacity to maximize cally addressed the effects of biomass re- deadwood produced by infestations elevate stored carbon and reduce the risk of cata- moval treatments on fire behavior and the the potential for high-severity fire and sub- strophic forest carbon loss (e.g., Lee et al. consequent carbon benefits. Fire and forest stantial carbon emissions when fires do oc- 2002, Li et al. 2007, Boerner et al. 2008, managers increasingly understand that such cur. Chiang et al. 2008, Hurteau and North treatments rarely prevent fire but, when suc- 2010). Most of these studies have not ac- cessful, tend to change fire type from crown Weather-Related Disturbances counted for the carbon stored in harvested to surface and reduce both fire intensity and Windthrow, hurricanes, and ice storms wood products and the carbon benefits of carbon emissions. When natural regenera- can be locally significant. A study of ice dam- offsetting fossil fuel–generated energy, let tion after fire is unlikely to occur, artificial age under climate change found that alone the substitution benefits of using regeneration can increase carbon storage thinned stands were more susceptible to ice wood instead of building materials which over time. damage but that ice damage became less are more fossil fuel intensive. Counting all likely under a changed climate (McCarthy et removals as instantaneous emissions, they Insects and Disease al. 2006). A single Katrina-sized hurricane generally conclude that fuel treatments in- Mortality wrought by insects and dis- has the potential to convert the live-tree crease carbon emissions. Counting fire-in- ease can rival that of fire and is a significant equivalent of 10% of US annual carbon se- duced mortality in untreated stands as forest factor in carbon emissions over time in for- questration into deadwood, much of which ecosystem carbon (e.g., Reinhardt and Hol- ests across the United States. These agents would be inaccessible and unrecoverable. singer 2010) provides an accurate estimate tend not to reduce dead biomass and soil Longer-term carbon losses result from the immediately after a fire but neglects the sig- carbon pools (as does fire); e.g., bark beetle delay in reestablishing full leaf area in hurri- nificant differences in photosynthesis and outbreaks generate considerable quantities cane-damaged stands (McNulty 2002). respiration between live and dead trees over of deadwood but may cause no change in Whether and how such disturbances might the next few decades. soil respiration rates (Morehouse et al. be managed to reduce carbon emissions is Such omissions preclude meaningful 2008). Their effect on forest carbon over unknown. interpretation of study results because fuel time depends in part on whether the agent treatments reduce the likelihood of cata- attacks all tree species in a stand or only a Land-Use Change strophic carbon loss via wildfire and, analo- few. As long as unaffected trees are present in In contrast with tropical forests, where gous to portfolio diversification, capture significant numbers, leaf area and growth land-use change is the leading driver of some portion of the forest carbon for prod- potential of the site “transfer” to the surviv- change in carbon stores and sequestration ucts and energy (and associated carbon ben- ing trees, at least some of which claim access capacity, the forested area in the United efits) well before a stand reaches full rotation to the growing space vacated by trees that States is essentially stable, with recent age (or experiences a stand-terminating dis- succumb. If the dead-tree carbon can be re- changes being well within the margin of er- turbance). Carrying less in-forest volume covered (e.g., via sanitation harvest for wood ror (USDA 2009). Smith et al. (2009) report (and carbon) is thus a desirable objective of products or energy), the effect on stand car- FIA estimates of 337,000 ha added to for- such treatments. Finkral and Evans (2008) bon trajectories would be little different ested area each year between 1997 and 2007, show how wood use can tip the balance to- than a thinning. However, if the stand is a on a base of 302 million ha. Statistics com- ward net carbon benefits. In a retrospective, monoculture or the agent attacks all tree spe- piled by US EPA (2010, Chapter 7) from model-based analysis of four large western cies, reversals in carbon storage may be sig- FIA, USDA’s Natural Resources Inventory, fires, Hurteau et al. (2008) found that had nificant, especially if salvage is not an option. and the Multi-Resolution Land Cover Con-

S18 Journal of Forestry • October/November 2011 (supplement) sortium suggest substantial, bidirectional Table 2-2. Area of US forestland, timberland, reserved forest, and low-productivity flux in area between grass and cropland and forest, by region (million hectares). forest, with more area entering than leaving forest. Moreover, a relatively small share Total Timberland Reserved Low-productivity (35%) of the area reported to have left forest Region forestland Total Natural Planted forest forest ends up in agricultural use, whereas 65% goes to settlements. Thus, the FIA-reported South 87 83 64 18 1 3 North 70 66 64 2 2 1 net annual increase in forestland area likely Pacific Coast 86 30 26 4 18 38 underestimates the carbon storage gains Rocky Mountains 61 29 28 0 8 24 because many of the forests converted to Interior Alaska 46 3 3 0 11 32 settlements retain all or most of their forest Tropical Islands 2 NA NA NA NA NA biomass. For example, in the western and Source: Smith et al (2009). northern states, the growth in the area of the wildland–urban intermix (where homes are scattered within a matrix of wildland vegetation) dwarfs that of the wildland–urban interface (where areas of high housing density abut areas of undeveloped wildland vegetation; Hammer et al. 2007). Even urban forests can retain as much as 30–50% of the standing forest carbon storage of their antecedent wildland forest and may grow faster because of the wider tree spacing, better control of competing vegetation in landscaped yards, and irrigation and fertilization by homeowners. Urban forests cannot dupli- cate all the functions of their wildland coun- terparts. The mere presence of humans reduces habitat quality for many species, but such forests can accumulate substantial quantities of carbon. However, eventual capture of that carbon in harvested wood products or as bioenergy (which would en- able urban forests to sequester yet more carbon via tree growth) is a nascent opportunity at best. Kline et al. (2004) found reduced Figure 2-1. Trends in US industrial roundwood, 1965–2005 (million cubic meters). (Source: incidence of forest management activity, in- Howard (2007).) cluding thinning and other harvest activity, in forests near settlements. Some micromills already glean timber supplies from urban The summary here provides national and productive forests (the remainder is gener- tree removal (e.g., Urban Hardwood Recov- regional context on the patterns of the ally in parks, wilderness, or other reserved ery 2010), and wood removed in urban set- movement of forest carbon from forests and areas typically off-limits to active manage- tings has been used for bioenergy produc- into wood products and energy. ment and considered inaccessible). Al- tion and district heating in St. Paul, Across the United States, forests differ though all forests may be subject to signifi- Minnesota, but it is doubtful that urban in how they are managed and how much cant disturbances spawned by climate trees’ carbon benefits (of in situ storage, carbon is removed to make products and en- change, mitigation via vegetation manage- long-term product storage, and substitu- ergy. Table 2-2 presents the area of forest- ment is most likely feasible only on accessi- tion) will ever approach what is possible on land across six major regions. We focus on ble timberland. undeveloped but managed forests. timberland, the more productive forest, in Since 1980, domestic production of the first four regions (i.e., excluding interior roundwood has fluctuated around 300 mil- Forest Carbon Accounting Alaska and the tropical islands, where tim- lion m3 of wood products while consump- Minimizing net emissions to the atmo- berland is scarce) because the data come tion has increased by more than 20% (Fig- sphere requires paying attention to sources from a common, contemporary database ure 2-1). Most of this gap has been filled and sinks both within the forest (net inven- (the assessments for the Resources Planning with imports from Canada and other coun- tory growth and mortality) and in the con- Act). This provides a more regionally nu- tries. Because harvesting in Canada had to sumer sector, where wood products can sub- anced view of US forests and their potential increase to fill this gap, Canadian forest car- stitute for energy- and emissions-intensive to generate climate benefits. These timber- bon stocks are lower than they would have materials such as concrete, steel, aluminum, lands represent about 60% of all US forest been otherwise. As a result, counting the in- plastic, heating oil, and coal (see Section 5). area and approximately 90% of the nation’s creased forest carbon sequestration in the

Journal of Forestry • October/November 2011 (supplement) S19 tality and logging residues will add to respiration-based carbon emissions even if they appear to be “storage” (in deadwood) in the year that a tree dies. At a smaller scale, near wood energy facilities, more of the net carbon flux commonly goes to fuelwood and other energy uses, and less of the carbon is left in the forest as logging residues or new mortality. Although the proportions vary across regions, nationally, a third of the total flux is taken out as products, a third adds to growing trees, and third goes into dead and down wood that will decompose over time. The annual flux from live trees into mortality from natural causes or logging is significant. In terms of new carbon storage, the deadwood is a “leaky bucket” because de-

composition rates and eventual CO2 release are high. Harmon et al. (2001) estimated decomposition rates for deadwood of 3%/ year for coniferous forests and 8%/year for deciduous forests, based on a review of more than 20 published and unpublished studies from temperate forests. Figure 2-2. Annual flux on timberlands in 2006, by region (million cubic meters of woody Table 2-3 summarizes the total forest biomass). (Source: Smith et al. (2009).) and forest product carbon flux by region after estimating the portion of harvested vol- Table 2-3. Total estimated annual biomass flux into products, new inventory, and ume of sawlogs and pulpwood used as en- mortality as a percentage of gross annual growth on US timberlands. ergy in mills and counting this as energy. Wood used for energy in the industrial sec- Out-of-mills flux and Pacific Rocky Total tor accounts for 67% of the total energy in-forest flux South North Coast Mountains United States wood category; residential (21%), electricity Final products 30% 15% 24% 12% 23% generation (8%), and commercial uses (3%) Energy 23 17 11 8 18 made up the rest (US EPA 2010). New growing inventory 19 36 35 36 28 Carbon fluxes from US forests vary by Logging residues 13 13 10 4 11 region and ownership. Forests in the South Natural mortality 15 19 21 40 19 are more intensively managed and have the Source: Calculated from Smith et al. (2009). lowest level of emissions related to natural mortality, and more of their gross growth is United States as new global climate carbon ers. The conversion of harvested volume converted into products and energy feed- sequestration benefits overstates the global into consumer products is determined at the stocks. Along the North and Pacific Coasts, benefits. mills as they respond to market price and the proportions of forest biomass going into Figure 2-2 combines forest inventory demand. About one-third of harvested vol- products and energy, new growing inven- and forest product data to illustrate the net ume goes into lumber products, with the re- tory, and mortality is approximately equal. flux in wood volume on US timberlands in mainder going into structural composite Forests in the Rocky Mountains have a large 2006. The measurements include changes in lumber, oriented strandboard, structural ratio of new inventory to harvested prod- both growing inventory and dead trees in and nonstructural panels, paper products, ucts, because there is little harvest activity in the forest. Each flux has a very different car- and fuelwood (Smith et al. 2009). Tradi- that region, but also have high flux into nat- bon trajectory over the next 100 years. Saw- tional forest inventory statistics focus on the ural mortality. Recognizing the regional logs can be used to create long-lasting wood live-tree inventory and apply no value to log- variations in where forest carbon accumu- products but account for only about one- ging residues and mortality left in the forest. lates is the key to interpreting national and half of the wood products used by consum- From a GHG perspective, both natural mor- sector-specific accounting.

S20 Journal of Forestry • October/November 2011 (supplement) section 3

Climate–Forest Interactions

ecause forests cover approximately residue is left on site to decompose (Amiro tradeoff between increased carbon storage 30% of the Earth’s land surface and 2006a). Although the carbon contained in and reductions in streamflow from affores- B store about 45% of terrestrial car- logging residues and dead trees is not con- tation in semiarid locations (Jackson et al. bon (Sabine et al. 2004), forests and global sidered as part of the growing stock in for- 2005). In boreal forest regions, warming has climate are closely linked. Recent empirical ests, the deadwood has a significant effect on also been associated with more fresh-water results (Baldocchi 2008) and climate models forest respiration and the net carbon flux at runoff into the Arctic Ocean and more area that now link the biosphere and atmosphere the forest level. of wetlands and water bodies that can be a (Bonan 2008) indicate that the interactions Carbon flux dynamics differ signifi- significant source of methane (Chapin et between forests and the atmosphere are cantly among the three forest biomes. For al. 2000). Some researchers have esti- highly complex. Climatic changes can affect instance, because most solar energy enter- mated that the climate implications of the existing forests, for example, though inci- ing the atmosphere is absorbed by the biogeophysical effects related to energy and dence of drought, fire, and reproductive cy- land and then transferred to the atmo- water fluxes are of a similar order of magni- cles of forest pests. Conversely, forests can sphere (McGuire and Chapin 2006), the tude as aboveground carbon sequestration affect climate in ways other than carbon role of forests in energy fluxes has consider- (Arneth et al. 2010). storage. An overview of the three major for- able relevance. A significant energy flux is est biomes (tropical, temperate, and boreal) the drop in the albedo (and the reflection of Climate-Related Characteristics solar energy back through the atmosphere) and the three major processes that connect of Forest Biomes forests with the climate (carbon, energy, and when dark-colored trees expand at the ex- New data on changes in tropical forest water fluxes) helps puts US forests in a global pense of snow-covered areas (Bonan 2008, cover have lowered the estimates of net context. Jackson et al. 2008, Anderson et al. 2011). A lower albedo decreases the fraction of solar greenhouse gas emissions from tropical de- energy that is immediately reflected. The ex- forestation and suggest an emphasis on de- Forest Biomes and pansion of boreal forests into areas that are forestation where carbon-rich peat soils are Forest–Atmosphere Fluxes currently tundra has been noted in many disturbed (van der Werf et al. 2009, The three major forest biomes have very northern latitudes. The energy feedbacks re- Friedlingstein et al. 2010). Nevertheless, a different biophysical dynamics with signifi- lated to decreased albedo from the natural review of numerous studies shows that when cant consequences for the atmosphere (Ta- movement of forests into tundra regions can all feedbacks are considered, tropical forests ble 3-1). The United States has all three have local as well as global impacts (Eu- are generally seen as the most effective for- types: 3.03 million km2 of temperate forests, skirchen et al. 2010). ests for providing climate benefits per unit of 0.46 million km2 of boreal forests, and 0.02 Links between water and carbon flux area or biomass (Jackson et al. 2008). million km2 of tropical forests (Smith et al. are seen most strongly in the tropics. The Although temperate forests cover the 2009). Total carbon storage is similar for most significant water flux linkage between least area of the three biomes, they are the each biome, even though photosynthesis is forests and the atmosphere is the evaporative source of most of the sustainably produced highest in the tropics and declines toward cooling from tropical forest canopies, which wood products. Temperate forests continue the poles. Only a fraction of the carbon has a positive relationship with cloud for- to increase as carbon sinks (Friedlingstein et captured by photosynthesis is added to mation and rainfall patterns (Fung et al. al. 2010) even though large quantities of carbon storage. A global review of net eco- 2005). Other research has pointed to a wood are removed annually. The current system carbon exchange concluded that Ϫ2 Ϫ1 “in general, 77 gC m year of carbon is Table 3-1. Area, storage, and gross photosynthesis of global forest biomes. lost by ecosystem respiration for every 100 Ϫ Ϫ gC m 2 year 1 gained by gross photosyn- Gross primary thesis when an ecosystem has not experi- productivity enced recent and significant disturbance” Forest area Total carbon (photosynthesis; (Baldocchi 2008). A synthesis of 10 car- Biome (million km2) storage (kg C/m2) kg C/m2 per yr) bon flux studies (Misson et al. 2007) con- Tropical forests 17.5 31.6 2.322 cluded that forest floor and soil respiration Temperate forests 10.4 28.1 0.954 made up around one-half of the total site Boreal forests 13.7 28.8 0.605 respiration. The increase in forest floor and Note: Total carbon storage includes vegetation and soil organic matter. soil respiration is proportional to how much Sources: Grace (2004), Anderson et al. (2011), and Beer et al. (2010).

Journal of Forestry • October/November 2011 (supplement) S21 Figure 3-1. Forest biomes’ atmospheric interactions and geographic distribution. (Source: Bonan (2008).) rate of carbon accumulation may decline, climates (Randerson 2006, Kurz et al. Atmospheric models and forest cover however, if the average age of the trees in US 2008b, Chapin et al. 2010). Outside the in- and forest inventory models give very dif- forests continues to increase (Albani et al. tensively managed boreal forests in Scandi- ferent estimates of the carbon, water, and 2006). Some researchers believe that man- navia, the natural forests in most other bo- energy balances of forests (Houghton 2003) agement can enhance forest productivity real regions may experience changes that are and, therefore, policy inferences drawn from even under changing climatic conditions. still only poorly understood (Amiro et al. any single model type may be highly mis- The key, they suggest, is matching seed 2006b, Euskirchen et al. 2009, Chapin et al. leading. Our understanding of forest dy- sources and silvicultural methods to future 2010). Such forests are believed to be less namics continues to improve with the devel- rather than historical climatic conditions amenable to cost-effective management in- opment of more accurate models that couple (Lindner and Karjalainen 2007, Nabuurs et terventions than temperate forests. the carbon in atmosphere with the carbon in al. 2007). Figure 3-1 highlights the relative mag- vegetation (Bonan 2008, Tjoelker et al. Boreal forests constitute 77% of Cana- nitudes of the three major fluxes (carbon, 2008, Beer et al. 2010, Yuan et al. 2010), dian forests (Natural Resources Canada water, and energy) for the three major forest make use of better field-based measurements 2005) and 13% of US forests (Smith et al. biomes. Focusing on only one or two of (Baldocchi 2008), and more effectively link 2009). These forests have already experi- these fluxes as guidance for forest climate process models and experimental field data enced significant changes due to warming policy may give a biased perspective. (Vargas et al. 2010). Better understanding

S22 Journal of Forestry • October/November 2011 (supplement) of the influence of nitrogen depositions on from fire suppression plays a role in increas- 2004), whereas outbreaks to the South have growth and soil respiration in temperate ing fire extent and intensity, Littell et al. been correlated with hotter, drier summers forests (Magnani et al. 2007) and global ni- (2009b) found that the predictors for large (Oneil 2006). In southern Alaska, spruce trogen fluxes (Thornton et al. 2009) is also fire years are all related to climate. Research- bark beetle outbreaks have been substantial clarifying the relevant feedbacks. ers predict at least a doubling of the area (Berg et al. 2006), causing 90% or higher burned annually for western forests (Mc- mortality in mature forest stands. These Climate Induces Disturbances Kenzie et al. 2004, Gedalof et al. 2005, outbreaks are associated with warm sum- and Mortality Westerling et al. 2006, Littell et al. 2009a) mers that permit bark beetles to change under moderate climate change scenarios. from a 2-year to a 1-year life cycle. For the Climate change will bring disturbances Massive and ongoing mountain pine western United States, summer tempera- that affect tree mortality and forest regen- beetle (Dendroctonus ponderosae; MPB) out- ture extremes and/or extended droughts eration. Drought and species range shifts breaks have affected the entire range of sus- are predicted under regional climate are mentioned as critical processes associated ceptible pine in the West from New Mexico change scenarios. Both conditions in- with climate change, but in western North to Alaska, and outbreaks of spruce bark crease tree mortality, either directly through America two processes dominate the discus- beetles (Dendroctonus rufipennis) have been die-off (Adams et al. 2009, Breshears et al. sion: wildfire and bark beetle outbreaks. significant in northern British Columbia 2009) or indirectly by increasing stress com- Wildfire is the dominant natural dis- and Alaska. Bark beetle outbreaks are a nat- plexes (McKenzie et al. 2008) that collec- turbance regime in western forests (Agee ural part of the western forest ecosystem, but tively cause large-scale mortality. The most 1993). Changes in wildfire behavior, extent, their severity and extent have dramatically likely scenarios involve greater water deficits frequency, and impact in the past 10 years increased in the past 10 years as a result of across drier areas of the West, leading to are notable (Calkin et al. 2005) and highly climate change (Logan and Powell 2001, species die-offs (Littell et al. 2009a). These correlated with changing temperature pat- Carroll et al. 2004, Logan et al. 2003, Gib- effects are not limited to western North terns and drought (McKenzie et al. 2004, son 2006, Oneil 2006). In more northerly America: Allen et al. (2010) found that cli- Gedalof et al. 2005, Westerling et al. 2006, regions, MPB outbreaks have been corre- mate change–related mortality driven by Littell et al. 2009b). Although fuel buildup lated with warmer winters (Carroll et al. water stress affects forests globally.

Journal of Forestry • October/November 2011 (supplement) S23 section 4

Biomass Use and Feedstock Issues

he supply of biomass as feedstock • Market price biomass is the amount of (Energy Information Administration 2010). for energy production depends not woody biomass that could be available at a The majority of bioenergy produced from T just on supply and demand but also given market price (e.g., Biomass Research woody biomass is consumed currently by the on the physical amounts from different and Development Initiative [BRDI] 2008, industrial sector—mostly at pulp and paper sources; delivered costs; and national, re- Walsh et al. 2003). mills that use heat and electricity produced on gional, state, and local laws, regulations, and • Supply curve biomass is the amount of site from mill residues (White 2010). But that policies. Regional variations influence the woody biomass available over a range of bio- is changing. As of January 2011, there were United States’ potential biomass supply and mass prices (White 2010). 445 (nonpulp and paper mill) operating and ultimately the placement of bioenergy facil- • Performance-based biomass is the announced wood-using bioenergy projects in ities. Whether biomass is removed and used amount of woody biomass available via a the United States, ranging from wood pellet for energy affects ecological systems and in- field verification of a coordinated resource mills and wood-to-electricity plants to pilot fluences long-term climate change mitiga- offering protocol (CROP). Developed for projects for cellulosic ethanol (Forisk Con- the US Forest Service, CROP is a tool for as- tion measures. sulting 2010). sessing biomass supply from land management Availability of Biomass agencies, based on “ability to perform” re- Factors that Affect Feedstock Biomass feedstocks for bioenergy and moval (versus potential to remove based primarily on inventory) (Mater and Gee 2011). Supply biofuel include forest and agricultural re- Changes in feedstock supply are con- sources, residuals from forest product mill The use of energy fuels has changed slowly over time. Wood served as the main troversial and a point of contention for com- operations, and municipal solid and urban peting industries (paper and pulp versus bio- waste wood (Perlack et al. 2005). Although form of energy for about half of the United States’ history. Coal surpassed wood in the energy), environmental groups, private each source is important, this article focuses late 19th century and was in turn overtaken landowners, and public land managers. The on forest resources—residues from timber by petroleum products in the mid-1900s. controversy is amplified by uncertainties harvest, hazardous fuel reduction, forest Natural gas consumption experienced rapid surrounding the effects of climate change on health restoration projects, and energy wood growth in the second half of the 20th cen- forests and the best mix of mitigation and plantations—based on forest growth, re- tury, and coal use also began to expand as the adaptation strategies to use across forest movals, and mortality (Figure 4-1). primary source of electric power generation types and landowner categories. Research The “Billion Ton Report” projected the potential amount of biomass to be as much as 1.2 billion tons of biomass availability annually in the United States (Perlack et al. 2005). It is now recognized, however, that the actual amount, given social, political, and market constraints, will be less (Sample et al. 2010, US DOE 2011). Five types of biomass have been defined (White 2010): • Potentially available biomass is all the woody biomass reported to be available. • Technically available biomass is the amount of woody biomass that can actually be used, determined as a percentage of potentially available biomass and representing the amount expected to be recoverable using current or expected technology (e.g., Perlack et al. 2005). Updated estimates of these volumes are also provided as available supplies based on accessibility and operability for Figure 4-1. US forest growth, removals, and mortality, 1952–2006. (Source: Based on each US region (Greene et al. 2010). Smith et al. 2009.)

S24 Journal of Forestry • October/November 2011 (supplement) has begun to analyze the perceived competi- years. Overall, documentation of negative tion of trees. Quality changes can affect pro- tion conflicts between traditional consum- effects on site productivity due to biomass cess efficiency in numerous ways, but reli- ing forest products mills and new wood en- removal is rare. able information concerning the effects is ergy plants. For example, Ince et al. (2011, Two recent meta-analyses of the scien- sparse (Dinus 2000, BRDI 2008, Sample et 142) modeled US forest sector market and tific literature suggest that effects of biomass al. 2010, White 2010). trade impacts of expansion in domestic harvest on biodiversity can vary by forest Short-rotation woody crops, such as wood energy consumption under hypothet- harvesting practice and other factors. Stud- shrub willow, hybrid poplar, southern pine, ical future US wood biomass energy policy ies of forest thinning have generally reported and eucalyptus, have the potential to increase scenarios. Bowyer (2011) also examined pol- positive or neutral effects on diversity and biomass feedstocks, but large-scale production icy implications for bioenergy development, abundance of terrestrial vertebrates and in- of these crops has yet to occur (Volk et al. in as well as the likely impact of global energy vertebrates across all taxa, although thinning press). Hybrid poplars grown in the Midwest, trends on biomass demand. intensity and the type of thinning may influ- South, and Pacific Northwest under intensive ence the magnitude of response (Verschuyl silviculture can provide biomass for energy as Environmental Consequences et al. 2011). Studies that document biodi- well as sawlogs, veneer logs, and fiber for the and Constraints versity response to harvest of coarse woody pulp and paper industry (Volk et al. in press). The ecological effects on soils, wildlife, debris and/or standing snags report substan- Coppice systems are still under development, fire regimes, and water quality of using bio- tially and consistently lower diversity and but yields from commercial plantations range mass for bioenergy depends on the existing abundance of cavity- and open-nesting birds from 9 to 10 oven-dry tonnes (odt)/ha per year condition of the forest stand and the amount and reduced invertebrate biomass in treat- in the Midwest to 18 odt/ha per year in the of biomass to be removed over a specific pe- ments with lower amounts of downed coarse Pacific Northwest (Netzer et al. 2002). With riod. The results depend on such factors as woody debris and/or standing snags (Riffell additional research, including breeding and the timing of removal and the nature of the et al. 2011). Effects of harvesting coarse and genetic advances, sustainable yields of 16, biomass (e.g., logging residues or short-rota- particularly fine woody debris on other taxa 24, and 36 odt/ha per year are possible in the tion woody crops; Pan et al. 2008, 2010, do not appear to be great, although there Midwest, South, and Pacific Northwest, respectively (Volk et al. in press). Hurteau et al. 2008). have been few studies of these practices (Rif- Pine and eucalyptus grown in the South There are concerns that if too many fell et al. 2011). With scientific support lack- also have the potential to supply biomass as bioenergy and biofuel plants are established ing for significant project level impacts, har- well as sawlogs and fiber. Loblolly pine’s over time they will not be sustainable. How- vesting guideline provisions should allow widespread cultivation and high growth ever, sustainable forest management prac- managers the flexibility to tailor prescriptions rates make it a likely candidate for short- tices are well known and widely practiced to site conditions and limiting factors and pro- rotation culture (Dickmann 2006), but ex- and can protect forests’ environmental and mote analysis of the impacts across a scale that tensive development is required. Eucalyptus ecological values. States such as Minnesota, includes numerous ownerships and projects. Wisconsin, and Pennsylvania, are develop- has been called an ideal species for biofuels ing woody biomass removal guidelines to Genetic Improvement and and bioenergy (Volk et al. in press), and in ensure small-scale and sustainable bioenergy Woody Crops the South, it can be produced and delivered plants can meet long-term environmental, Genetic tree improvement programs have at a cost competitive with grasses and other ecological, and economic needs. Use of for- focused on improving phenotypic characteris- hardwoods. Under the right growing conditions, it can produce more than 29 odt/ha per estry best management practices and certifi- tics, predominantly to increase volume for year for either biomass feedstock or ethanol cation systems such as the American Tree timber production. Today, mostly private (Gonzalez et al. 2009, 2010, 2011a, 2011b). Farm System, Sustainable Forestry Initia- companies are investing in poplar and willow tive, and Forest Stewardship Council is also to increase feedstocks through advanced ge- Economics widespread. netics in tree selection. Mass control polli- Traditional forest products such as saw- There can be environmental tradeoffs nated and varietal pine seedlings that exhibit timber and pulpwood are more or less com- involved in removing harvesting residuals genetic gains are now available (Dougherty plementary uses, because pulpwood can be where the residuals have value in maintain- 2007). managed to become sawtimber. Forest bio- ing site productivity and biodiversity. Site Poplar breeders in the United States mass, at least for energy generation, can responses to residue removal and retention have focused on increasing adaptability, come from pulpwood-size trees, which are depend on site conditions and limiting fac- growth rates, and pest and stress resistance. easily substituted: established markets, tors. Scientific evidence from sites across Significant increases have been achieved silvicultural systems, and harvesting and North America suggests that the productiv- through traditional selection and breeding logistics supply chains already exist. Al- ity of most sites is largely resilient to remov- along with intensified cultural practices. Ef- though traditional pulpwood harvesting ing harvesting residuals (Powers et al. 2005). ficiencies have also been gained in harvesting can accommodate small woody biomass For instance, Westbrook et al. (2007) found and handling. Opportunities for manipulat- and forest residue collection, there is a that even with removal of all harvesting res- ing feedstock quality have long been recog- point at which production efficiency suf- idues and all nonmerchantable woody bio- nized but have gone largely unrealized be- fers (Westbrook et al. 2007). Price to the mass between 1- and 4-in. dbh, nutrient cause of uncertainties over which traits to landowner will invariably be a determin- losses from a Georgia pine plantation were modify for what process and because of ing factor of end use. The traditional for- expected to be replaced by precipitation in 5 some social resistance to genetic modifica- est products industry, particularly the pulp

Journal of Forestry • October/November 2011 (supplement) S25 and paper sector, has already seen price munities, and includes the Biomass Crop which vary based on the type of owner- competition for pulpwood to be turned into Assistance Program (BCAP). ship. Numerous studies have documented pellets (Greene et al. 2010). Differing and often conflicting defini- that for nonindustrial private forest land- tions of renewable biomass in current federal owners, harvesting is often a secondary objec- Government Policy energy policies hinders policy implementa- tive (e.g., Butler 2008). Even industrial and The Biomass Research and Develop- tion and the development of biomass mar- those nonindustrial private forest landowners ment Act of 2000 authorized an interagency kets. A universal definition of renewable interested in harvesting forest biomass are of- board (representing USDA, Department of biomass that includes renewable, sustainable ten reluctant to engage in the long-term con- Energy, Department of the Interior, and the forest biomass—and does not confound this tracts necessary to participate in forest carbon Environmental Protection Agency) to pro- definition by attempting to address other offset projects. mote development of biofuels in the United policy goals—would promote the develop- Nonindustrial forest landowners who States. The Board recently issued an eight- ment of sustainable energy and environmen- seek maximum revenue, may plant short- point strategic plan focused on this goal. tal policies on appropriate lands. rotation woody crops, such as hybrid popu- Agency coordination was recognized as A further problem is that policies de- lar or willow, in response to the incentives important given often conflicting agency signed to promote the use of forest biomass created by BCAP. For example, Gan et al. initiatives and guidance from Congress. For energy have focused on development of instance, the Energy Policy Act of 2005 dis- transportation fuels despite public concerns (in press) found that without financial in- allowed the use of federal woody biomass about this direction. As Caputo (2009) de- centives and technical assistance, fewer than for the renewable energy credit. In contrast, scribes the situation: 6% of landowners would be willing to thin forest stands for energy production even if it Section 203 of the Healthy Forests Restora- … federal incentives have largely focused tion Act of 2003 (PL 108-148, codified at 16 on the production of renewable transporta- reduced fire hazard, but with government tion fuels and co-products. Input from cost sharing and technical assistance for US Code Section 6531) provided authority stakeholders indicates that future policies for the Biomass Commercial Utilization should focus on improving forest sustain- growing biomass, two-thirds of timberland Grants Program, which emphasizes the use ability, increasing research capabilities, and landowners would consider producing bio- improving the economics of biomass utili- mass for bioenergy purposes. The most rea- of woody biomass especially from wildfire- zation. Additionally, many feel that the affected areas in the wildland–urban in- production of heat and power should be sonable expectation about biomass produc- terface. The Food, Conservation, and En- given similar attention to the production of tion by private landowners is that they will liquid transportation fuels as an important be guided by economic reality and sustain- ergy Act of 2008 (PL 110-234; Farm Bill use for woody biomass. 2008), under Title IX, Section 9011-9013, ability. High transaction costs can prevent promotes the use of woody biomass for re- Landowner Preferences interested nonindustrial landowners with search and development of biofuels, wood- The availability of biomass feedstocks small acreage from participating in biomass to-energy programs for states and local com- will also depend on landowner preferences, projects.

S26 Journal of Forestry • October/November 2011 (supplement) section 5

Wood–Fossil Fuel Substitution Effects

hen trees are harvested, carbon products in use and in landfills during duce, because only minimal processing is is removed from the forest. It is 2005–2007 was estimated at 2.3–2.4 billion needed to convert the naturally produced W tempting to conclude that forest tonnes—equivalent to 5.2–5.7% of forest wood to desired shapes (Milota et al. 2005, harvesting should be avoided to reduce car- carbon pools. Puettmann et al. 2010). Wood products, bon emissions and maximize carbon storage. Carbon was sequestered in US forests such as furniture, require more steps in pro- However, careful consideration of carbon during 2005–2007 at a rate of 192 million cessing and therefore more energy (e.g., Pu- flows reveals that conversion of wood to use- tonnes/year. The annual rate of carbon ac- ettmann and Wilson 2005, Wilson 2010) ful products can significantly reduce overall cumulation within wood products in use but still significantly less energy than non- societal carbon emissions. Major consider- and in landfills was estimated at about wood materials (Lippke et al. 2010). ations are the low carbon emissions associ- 28–29 million tonnes—14.8% of the rate of Not only does production of lumber ated with wood products manufacture, car- sequestration within forests and 22–23% of and wood products require relatively little bon storage in long-lasting wood products, the annual additions to nonsoil forest car- additional energy beyond the solar energy avoided emissions that result when wood is bon stocks (US EPA 2010). Rates of accu- used in tree growth and wood production, used in place of energy-intensive materials mulation in harvested wood products were but very little of that additional energy and products, and the efficient use of wood notably lower in 2008–2010 because of the comes from fossil fuels. In the United States residues for energy. sharp decrease in overall economic activity in 2008, renewable energy produced from To arrive at a cogent picture of the for- and home construction. tree bark, sawdust, manufacturing and har- est sector’s overall effects on atmospheric Much of the carbon in wood products vest residuals, and byproducts of pulping in carbon, we need to understand the material resides in the nation’s housing, as well as in papermaking processes provided 65% of the and energy flows as inputs and outputs commercial, industrial, public, and other energy used in manufacturing paper prod- within well-defined system boundaries. structures. Wood-framed buildings make up ucts and more than 73% of the energy used Analysis using attributional life-cycle assess- about 90% of homes in the United States, in manufacturing wood products (American ment (LCA) methods that measure inputs and in all homes, whether wood framed or Forest and Paper Association 2010). In the and outputs within a system boundary ex- not, wood furniture, cabinets, flooring, and same year, the wood and paper industries of plains the interactions at that scale. We then trim are dominant. the United States accounted for 94% of the need to integrate these effects across system manufacturing sector’s derived renewable boundaries to see how substitution of har- Emissions from Wood Products fuel use, and they generated 37% of the total vested wood products for fossil fuels and fos- Manufacture energy produced by cogeneration-capable sil fuel–intensive products can offset the The carbon dioxide that is removed systems within all manufacturing sectors. flow of carbon dioxide from fossil fuel re- from the air as a tree grows is combined with Because wood is produced using solar serves to the atmosphere. water and converted to simple sugars within energy, the manufacture of lumber and the leaves, conveyed downward through other wood products requires little addi- Product Flows of Harvested the branches and bole in the form of sap, tional energy. Moreover, only one-quarter Wood and then converted into complex polymers to one-third of the energy consumed is fossil Carbon makes up a considerable pro- that combine to form an intricately struc- energy. The result is that total emissions portion of wood volume, amounting to tured polymeric material that has a higher from wood products manufacture, includ- about 50% of the moisture-free weight. strength-to-weight ratio than structural ing emissions of carbon dioxide, are typically Within forests, significant quantities of car- steel. That this natural process uses freely lower than for potential wood substitutes on bon are stored (or sequestered) in the twigs, available solar energy largely explains why a weight or mass basis (Table 5-1). For ex- branches, boles, and roots of trees. Addi- the energy embodied in wood products is ample, carbon emissions for the manufac- tional carbon is stored in forest litter and lower than for any other construction mate- ture of a tonne of lumber are markedly less forest soils. In 2005–2009, some 24–25 bil- rial (Glover et al. 2002, Perez-Garcia et al. than for a tonne of steel, plastic, or alumi- lion tonnes of carbon was stored in standing 2005, Gustavsson and Sathre 2006, Lippke num. trees, forest litter, and other woody debris in et al. 2010). “Embodied energy” refers to the US forests, and another 20–21 billion quantity of energy required by all the activ- Product Substitution tonnes was in forest soils and roots (US En- ities associated with a production process, For every use of wood there are substi- vironmental Protection Agency [EPA] including gathering, transporting, and pri- tutes: wood studs can be replaced by steel 2010). Carbon is also found within har- mary processing of raw materials. Lumber, studs, wood joists by steel I-joists, wood vested wood products. The carbon in wood in particular, requires little energy to pro- walls by concrete walls, wood floors by con-

Journal of Forestry • October/November 2011 (supplement) S27 Table 5-1. Net carbon emissions in manufacture per tonnes.

Net emissions Material (tCe)

Framing lumber 0.033 Concrete 0.034 Concrete block 0.038 Medium-density ﬁberboard (virgin ﬁber) 0.088 Brick 0.088 Glass 0.154 Recycled steel (100% from scrap) 0.220 Cement (Portland, masonry) 0.265 Recycled aluminum (100% recycled 0.309 content) Steel (virgin) 0.694 Molded plastic 2.502 Aluminum (virgin) 4.529

Notes: Values are based on life-cycle assessment and include gathering and processing of raw materials, primary and secondary processing, and transportation; a 10% increase in energy Figure 5-1. Process emissions less carbon stored in ﬂoor structure components and ,oriented-strand board ؍ engineered wood product, OSB ؍ consumption is assumed for the production of concrete block. assemblies. Notes: EWP ؍ .tC, tonnes of carbon equivalent Sources: Based on US EPA (2006, Exhibit 2–3); data for con- Dim dimension lumber. (Source: Adapted from Lippke and Edmonds (2009).) crete is from Flower and Sanjayan (2007).

floors, and sheathing. Wood fares well in assembly groups affected by changes in crete slab floors, and biofuel by fossil fuel. such comparisons because of its high material use (i.e., walls, floors, and roofs) Every product use has its own life-cycle car- strength relative to weight, its low embodied revealed more pronounced differences. bon footprint (Perez-Garcia et al. 2005, energy, and carbon stored in the product it- For instance, compared with the wood de- Lippke and Edmonds 2009). Using life- self. Lippke and Edmonds (2009) show the sign, the steel design’s floors and roof were cycle inventory (LCIs), which include the relative process emissions and stored carbon found to embody 245% more energy and carbon stored in wood as well as the process- per functional unit for wood and nonwood produce a corresponding increase in global ing emissions to harvest, transport, and products (Figure 5-1). In Figure 5-1 the ver- warming potential. In the Atlanta compari- make the product, one can compare the net tical zero line is where process emissions son, increases in embodied energy and carbon consequences of substituting one equal carbon stored. A component (black global warming potential were determined product for another. bars) or assembly (green bars) to the right of to be 41% and 65% higher for concrete Life-cycle analyses have shown marked the zero line produces more emissions than construction than for wood houses, re- differences in energy requirements and car- it stores, and one to the left of the line stores spectively. Comparisons of building com- bon emissions associated with different more carbon than it takes to produce (i.e., is ponents made to specified codes using building materials and the structures made a carbon sink) as long as the product remains wood, steel, and concrete options show that from them (Glover et al. 2002, Gustavsson in use. Longer useful life, recycling, and re- wood designs produce not only the lowest and Sathre 2006, 2011, Perez-Garcia et al. use extend the period of this offset. Similar global warming potential, but also provide 2005, Buchanan 2007, Gerilla et al. 2007, charts for wall assemblies (not shown) show the lowest emissions to air and water. (See, Salazar and Meil 2009, Lippke et al. 2010). the same patterns, with wood products stor- for example, Table 3-1, Malmsheimer et al. Comparisons of structures having compara- ing more carbon than is emitted during their 2008). Only in the solid waste category does ble heating and cooling requirements show harvest and manufacturing. wood fare worse than steel, a result that that wood products and structures require Another study compared wood and arises because steel is precut and wood is cut the least energy to produce and conse- steel houses built to Minneapolis code stan- on site during construction (Lippke and Ed- quently have the lowest greenhouse gas dards and wood and concrete houses built to monds 2006). Further examination of fossil (GHG) emissions profile. Thus, substitut- Atlanta code standards (Meil et al. 2010). fuel consumption and associated carbon ing wood for more energy-intensive, non- The two designs shared many of the same emissions, linked to construction of entire renewable materials produces a substantial structural assemblies (i.e., foundation foot- structures, reveals that differences in global net reduction in carbon emissions, called the ings and basement block wall, support warming potential for the various designs substitution effect. In addition, wood stores beams and jack posts, and roof), and there- are in nearly direct proportion to the differ- carbon for the useful life of the product, en- fore the differences in the environmental ef- ences in fossil fuel consumption (Tables 5-2 hancing the benefits of wood relative to fects can be traced to their respective wall and 5-3). other building materials. and floor assemblies. For the Minneapolis An analysis of carbon storage and The comparisons in Table 5-1 are per house, the steel design was found to embody avoided emissions for wood versus steel tonne of product. More appropriate com- 66% more energy (measured in megajoules construction in a large wood structure also parisons, which reflect the functions that per square foot of assembly) and generated illustrates the carbon-related advantages of products perform, have been made between 49% more global warming potential than wood (Table 5-4). The completed structure, wood and nonwood assemblies for walls, the wood design. Focusing on only the in Anaheim, California, comprises five sto-

S28 Journal of Forestry • October/November 2011 (supplement) Table 5-2. Consumption of fossil fuels Table 5-3. Consumption of fossil fuels Table 5-4. Carbon storage and avoided associated with exterior wall designs in associated with ﬂoor designs (excluding emissions from wood versus steel warm climate home. insulation). commercial/residential complex.

Fossil fuel energy (MJ/ft2) Fossil fuel energy Carbon sequestered and stored (CO2e) 3,970 tonnes 2 Avoided greenhouse gases (CO e) 8,440 tonnes Lumber-framed Concrete (MJ/ft ) 2 wall wall Total potential carbon benefit (CO2e) 12,410 tonnes Dimension wood joist floor 9.93 a Concrete slab floor 24.75 Source: This case study is based on use of the Forintek Wood Structural components 6.27 75.89 Carbon Calculator for Buildings based on research by Sathre b Steel joist floor 48.32 Insulation 8.51 8.51 and O’Connor (2010) and is described by WoodWorks (2011). Claddingc 22.31 8.09 Source: Edmonds and Lippke (2004). Totald 37.09 92.49 rates for common building products. They a Includes studs and plywood sheathing for the lumber-framed well into advanced years (Curtis and Mar- arrived at a value of 2.1 tonnes of carbon wall design and concrete blocks and studs (used in a furred-out wood stud wall) for the concrete wall design. shall 1993). Other species with growth rates displaced per tonne of wood carbon used. b Includes fiberglass and six-mil polyethylene vapor barrier for that peak sooner show even larger differ- This is a more general characterization of both designs. c Includes interior and exterior wall coverings. Exterior wall ences in the relative carbon sequestration be- substitution across all wood uses than the coverings are vinyl (lumber-framed wall design) and stucco tween managed and unmanaged forests. specific examples shown in Figures 5-1 and (concrete wall design). Interior wall coverings gypsum for both designs. These trajectories show the relative carbon 5-2 and Tables 5-3 and 5-4. d Includes subtotals from structural, insulation, and cladding consequences assuming a change in manage- categories. Source: Edmonds and Lippke (2004). ment intent at the point when the first thin- End-of-Life Considerations ning was implemented. In practice, a no- Based on census data, the half-life of the harvest forest scenario would more often US housing stock is approximately 80 years ries of wood frame construction over a con- than not have a lower forest growth trajec- (Table 5-5; Winistorfer et al. 2005). First- crete parking garage and first level and in- tory because the investment in regenerating order decay functions have often been used cludes 251 luxury apartment units and 2 2 the forest from bare land would not have to estimate losses of wood in use over time 13,000 ft (1,208 m ) of retail space. The 3 occurred without the expectation of a return (e.g., Intergovernment Panel on Climate structure incorporates 5,201 m of wood, on the investment in later years. Change [IPCC] 2007b), but they greatly with resulting long-term storage of 3,970 As the examples illustrate, substitution overestimate early losses because they as- tonnes of equivalent carbon (CO e), with 2 values vary with the wood product or assem- sume the highest decay (loss) rate when there twice that level of avoided GHG emissions bly in question and its alternative. Sathre is the most stock, with a declining rate there- resulting from selection of wood rather than and O’Connor (2010) conducted a meta- after. Because houses are rarely demolished traditional steel construction. analysis to estimate average substitution in their first 10 years, first-order decay func- The effect of substitution on a per hectare basis is illustrated in Figure 5-2, which compares substitution of wood for concrete in construction and its carbon implications over a timeline of two rotations of a forest initially planted on bare land. Carbon stored in products (designated as “products carbon”) is significant relative to the carbon stored in the live- and dead-tree biomass (designated as “forest carbon”). Further- more, well before the end of two rotations, overall sequestration of carbon (forest carbon plus products carbon plus substitution carbon) far exceeds carbon sequestration in an unmanaged forest (i.e., a forest managed without timber extraction, shown as the dotted line designated as “no-harvest carbon”). The figure includes the carbon emissions associated with generation of bioenergy from short-lived product pools, taking into account that the efficiency of the conversion of wood to energy is lower than for gas- or coal- Figure 5-2. Carbon (tonnes per hectare) stored in forests (designated as “forest carbon”) in products (designated as “products carbon”), and retained in the lithosphere because of fired boilers. A net benefit in this case ap- substitution for concrete and fossil fuel energy (designated as “substitution carbon”), pears about 30 years after stand establish- compared with carbon stored in an unmanaged forest (dotted line designated as “no- ment, with benefits increasing over time. harvest carbon”), per hectare of forest. Notes: Douglas-fir forest, 80-year rotation, with The managed and no-harvest forest scenar- intermediate thinnings at years 30 and 60; portion of wood harvested at rotation age used ios both use growth trends in Douglas-fir, a for long-lived construction products; dotted line indicates unmanaged forest. (Sources: species that is known to maintain growth Perez-Garcia et al. (2005), Wilson (2006).)

Journal of Forestry • October/November 2011 (supplement) S29 Table 5-5. Projected half-lives for end uses Table 5-6. Fate of material in solid waste Using biomass instead of fossil fuels for of wood. disposal sites. meeting energy needs has several advantages. Specific benefits depend on the source Half-life Half-life of the wood (and its alternative fate if not Use (yr) Fraction of used for energy) and the intended use. Ben- permanently Fraction decaying efits can include reduction of GHG emis- Single-family home (1920 and before) 78.0 sequestered that decays portion Single-family home (1921–1939) 78.8 sions (particularly CO2) and other air pol- Single-family home (1939–) 85.0a Solid wood 77% 23% 29.0 yr lutants, energy cost savings, local economic Multifamily home (as fraction of half-life 52.3b Paper 44% 56% 14.5 yr development, reduction in waste sent to for single-family home) Housing alteration and repair (as fraction 25.7c Source: Based on Skog (2008). landfills, and the security of a domestic fuel of half-life for single-family home) supply. In comparison with other renewable All other uses for solidwood products 38.0 paper that contains a large fraction of carbon energy sources, such as wind and solar Paper 2.5 that is degradable under anaerobic condi- power, biomass is more flexible (e.g., can a Based on half-life increase per 20 yr for post-1939 period. tions. This suggests that incentives should be generate both power and heat) and reliable, b Based on half-life of multifamily home that is 0.61 of single- high to reuse paper and wood, recycle it, or because it is a nonintermittent energy source family home. c Based on half-life of repair and remodel that is 0.30 of single- burn it to recover its heating value, and that whereas the alternatives rely on the weather. family home. landfills should be managed to recapture the In the United States, the potential role Source: Based on Skog (2008). energy value of methane emissions. Collec- of forest bioenergy is readily accepted by pri- tion systems are evolving rapidly. For exam- vate parties in regions where relatively low tions fail to capture the carbon storage po- ple, US EPA (2007b) reported that the re- value pulp is the major output (Galik et al. tential of long-lived materials. An alternative covery or oxidization of methane increased 2009a). It is more controversial in the con- approach has been proposed by Marland et from 20 to 50% between 1990 and 2006. text of public forests. As in Europe, the pur- al. (2010), who applied gamma functions to Methane capture from landfills is one of the suit of aggressive bioenergy targets in the distributed product pools so that short-lived most cost-effective investments for atmo- United States could affect traditional users products, such as paper, decay quickly but spheric GHG reduction because of the dual of industrial roundwood, especially pulp long-lived products, such as oriented strand- benefit stream of reducing methane release producers in the southeast region of the board and lumber, decay more slowly. Re- (methane has 25 times the global warming country (Abt et al. 2010), but in other areas finement of the parameters used by Marland potential of CO2; Forster et al. 2007) and of the country it could create opportunities et al. (2010) to reflect actual decay rates on a converting the methane into usable energy for synergy. Increasing the use of managed regional, national, or wood basket basis is that offsets fossil fuel emissions. forests for biomass could enhance forest needed, but the functional form improves resiliency and productivity without using on previous estimates of decay rates. Wood Energy scarce high-quality agricultural land or irri- The collection efficiencies of landfilling The US Department of Energy (DOE) gation water. have carbon storage implications (Skog estimatesthatin2009,about8%(7.75quad- 2008). Of the wood products that enter rillion Btu) of the energy consumed in the Heat and Power (Combustion solid waste disposal sites, more than three- United States came from renewable sources and Gasification) quarters of the carbon in solid wood and (excluding ethanol; US DOE 2010). For Of the 9,709 megawatts (MW) of bio- almost one-half of the carbon in paper is 2004–2008, about 30% (2.1 quadrillion mass electric capacity in the United States in never released to the atmosphere (Table Btu) of this renewable energy was supplied 2004, about 5,891 MW (61%) was gener- 5-6). The carbon that is released during de- from woody biomass, equivalent to about ated from wood and wood wastes. Another cay takes many years to reach the atmo- 2% of annual energy consumption from all 3,319 MW of generating capacity was from sphere. For example, the 23% of the solid sources and the largest source of renewable municipal solid waste and landfill gas, and wood that does decay has a half-life of 29 energy after hydropower (US DOE 2009). 499 MW of capacity was attributable to years. Skog (2008) found that when paper is Renewable energy consumption (excluding other biomass, such as agricultural residues, landfilled, the nonlignin component (56%) ethanol) is projected to increase to 8.4 quad- sludge, and anaerobic digester gas (US EPA decays, leaving the lignin component (44%) rillion Btu by 2015 and to 9.7 quadrillion 2007a). as a long-term store in the landfill (Table Btu by 2030. Assuming the current share of Much of the biomass used for energy, 5-6). This nondegradable fraction varies by renewable energy coming from woody bio- especially the biomass burned in pulp mills, grade, from approximately 10% for mass remains static, woody biomass would is burned in combined heat and power bleached chemical pulp fibers to 85% for be the source of about 2.5 quadrillion Btu of (CHP) systems. CHP is not a single technol- mechanical pulp fibers (US EPA 2006). energy in 2015 and 2.9 quadrillion Btu of ogy but an integrated energy system that can Methane emissions from wood degra- energy in 2030. At present, wood energy be modified depending on the needs of the dation in a landfill can offset any benefits of consumption requires about 111 million energy end user. The hallmark of all well- carbon stored there. Heath et al. (2010) oven-dry tonnes (odt) of woody material designed CHP systems is an increase in the found that with current landfill design and annually (assuming 17.2 million Btu/odt of efficiency of fuel use. By using waste heat operating practices, US landfills appear to be wood). Under DOE’s reference projection, recovery technology to capture a signifi- a net long-term sink for carbon in wood approximately 132 million odt of wood will cant proportion of heat created as a byprod- products but a long-term source of GHG be used for energy in 2015 and 152 million uct in electricity generation, CHP typically emissions from paper products, particularly odt will be used in 2030 (White 2010). achieves total system efficiencies of 60–80%

S30 Journal of Forestry • October/November 2011 (supplement) for producing electricity and thermal en- values from Wiedinmyer et al. (2006) to Current protocols and policies generally do ergy. These efficiency gains improve the eco- compare the implications of thinning to re- not allow this credit (see Section 6). nomics of using biomass fuels, as well as produce fire risk versus stand-replacing wild- Potential biofuel feedstock that burns duce other environmental benefits. More fires. Because open burning generates meth- or decays in the woods is a net decrease in the than 60% of all biomass-powered electricity ane and nitrous oxides, two potent GHGs, carbon stock—the equivalent of an emis- generation in the United States is in the burning a tonne of biomass in a wildfire gen- sion. The loss of carbon from the forest is form of CHP (US EPA 2007a). erates more emissions in CO2e than the car- already accounted for in the forest carbon bon content of the wood burned. Burning stock change, but care must be taken when Energy Balance and Benefits of the same wood under controlled conditions extrapolating the results from a single stand Biomass Energy in a boiler reduces non-CO2 emissions by up to a wider context (Figure 5-3). For a single A small amount of fossil fuel is used to to 98% while generating energy. The substi- stand under sustainable management, the produce bioenergy—approximately1Uof tution of woody biomass for fossil fuel en- forest carbon cycles around some average fossil fuel for every 25–50 U of bioenergy ergy provides a GHG offset because the fos- value that is contingent on inherent site pro- (Bo¨rjesson 1996, Boman and Turnbull sil fuel remains underground and the flow of ductivity, rotation age, and species mix, and 1997, McLaughlin and Walsh 1998, Mat- fossil carbon to the atmosphere is reduced. there is a time interval between uptake and thews and Mortimer 2000, Malkki and Thus, harvesting woody biomass to re- release of carbon (Figure 5-3a). However, no Virtanen 2003, Matthews and Robertson duce wildfire risk, damage, and, ultimately, processing facility relies on a single stand to 2005). Biofuels (transportation fuels) typi- emissions delivers an additional atmo- provide feedstock, so extrapolating the time- cally require more input energy, so the en- spheric benefit beyond the substitution of dependent dimension of a single stand anal- ergy balance for producing biofuels is less fossil fuel (Mason et al. 2006, Hurteau et al. ysis to the emissions profile of a facility is favorable, as well as more variable—approx- 2008, Stephens et al. 2009, Reinhardt and inappropriate and leads to incorrect conclu- imately1Uoffossil energy for every 4–5 U Holsinger 2010). That additional benefit is sions (O’Laughlin 2010). of bioenergy (Gustavsson et al. 1995). Net constrained, however, by the number of A more correct characterization of the carbon emissions from generation of a unit treatments and their spatial extent: limited effects of harvesting biofuel uses a landscape- of electricity from bioenergy can be 10– treatments may not be sufficient at the land- level analysis to determine whether the har- ϩ 30 times lower than emissions from fossil- scape scale (Reinhardt and Holsinger 2010). vest needed to sustain processing facilities based electricity generation, depending on The effectiveness of the benefit is also con- within an economic haul distance increases the systems and fuel types being compared strained by the ecology of the forests in ques- or decreases average carbon stores on the (Boman and Turnbull 1997, Matthews and tion. For example, in a detailed analysis of land. If harvesting results in a stable average Mortimer 2000, Spath and Mann 2000, fire risk reduction treatments for Pacific of carbon across the total forest through Mann and Spath 2001, Matthews and Rob- Northwest coastal western hemlock–Doug- time (Figure 5-3b), the forest itself is car- ertson 2005, Cherubini et al. 2009). las-fir and western hemlock–sitka spruce bon-cycle neutral. If forest carbon stocks are Although energy self-sufficiency is one forests with 500-year fire return intervals, unaffected by the choice between forest bio- reason for pursuing the development of Mitchell et al. (2009) found that the treat- mass and fossil fuels, the products removed woody biomass-to-energy initiatives (En- ments would be ineffective at reducing car- from the forest provide a carbon benefit to ergy Independence and Security Act 2007), bon dioxide emissions and that leaving the the atmosphere equal to the avoided emis- there are other reasons to use woody biomass forests untreated would be a better option. sions from fossil fuels less any fossil energy it as an energy source. In the West, wildfire This result is not unexpected in a region took to produce energy from the biomass risk is high and increasing, and removing where fire is rare and fire risk reduction treat- feedstock. To meet this condition, it is nec- excess biomass to reduce risks is desirable in ments are highly unlikely. essary to ensure that harvests and mortality many cases. Reducing fire risk while main- do not exceed net growth across the forest taining other forest values often entails re- Energy Substitution and that soil conditions and carbon seques- moving low-value material while retaining The substitution effect noted in con- tration potential are maintained. higher-value trees for other purposes. With- junction with production and use of wood An analysis using publicly available data out a viable economic return for woody bioproducts rather than metals, plastics, or con- from the US LCI database (National Re- mass that is removed, the costs are prohibi- crete also applies to use of wood in produc- newable Energy Lab 2011) and the EPA tive and the likelihood of action is low. tion of energy. Using wood to produce elec- TRACI Impact method found that the Wildfire emissions are equal to 5% of tricity, heat, liquid fuels, or other forms of global warming potential for a cradle-to- total GHG emissions in the continental energy avoids the flow of fossil carbon to the grave analysis was greater for coal than for United States (Wiedinmyer et al. 2006). atmosphere, provided that energy offsets the woody biomass (Figure 5-4; Lippke et al. Avoiding wildfire emissions by thinning sus- use of fossil fuels. Although a CO2 molecule 2011). The comparison in Figure 5-4 is for ceptible forests and using the harvested ma- isaCO2 molecule, regardless of source, the cleanest coal type (bituminous); other terial as a woody biomass feedstock is a po- crediting biofuel use as a fossil fuel offset coal types produce more emissions and tentially valuable side benefit that is often recognizes the reduction of the flow of fossil therefore produce an even larger differential ignored in the assessment of the carbon con- carbon. Consistent carbon accounting between the fuel types. Results show that if sequences of bioenergy. Oneil and Lippke counts the emissions and takes credit for the the uptake of CO2 in the forest is ignored, (2010) calculated the GHG forcing per offset value (i.e., the amount of fossil fuel disregarding the fundamental difference be- tonne of biomass burned during wildfires carbon that was not emitted, net of the fossil tween renewable and nonrenewable fuels, using default emission and consumption fuel used to produce the biomass energy). emissions from using biomass as a feedstock

Journal of Forestry • October/November 2011 (supplement) S31 for long periods of time. Using a single stand or project to model a wood supply system can severely distort systemwide outcomes (Lucier 2010). At the scale of a wood supply area, sustained-yield forestry and sustainable management systems keep growth and removals in balance, and the loss of carbon from harvests in any given year is equal to gains in carbon elsewhere in the area. The net change in carbon stocks in all years is then zero; i.e., net removals of carbon from the atmosphere equal the amount of carbon in wood removed from the forest, and the system is carbon neutral. The variation in definitions of carbon neutral (Table 5-7), however, suggests the need for elaboration when using the term. Even if forestland is maintained as forestland, deviations from carbon-cycle neutrality can occur in both directions. Climate change, more frequent insect and disease outbreaks, exotic and/or invasive disturbance agents, failure to regenerate, and severe wildfires that reduce soil productivity can affect long-term carbon storage potential. Ensuring continued carbon benefits from the forest sector requires maintaining long-term site productivity. Given adequate nitrogen supplies to maintain carbon stores in dynamic equilibrium, average forest carbon stores can increase concurrent with ecological protections, such as riparian buffers and habitat requirements. Incorporating Figure 5-3. Forest carbon under sustainable management, by (a) single hectare and (b) most ecological sustainability criteria into landscape. (Source: Oneil et al. 2011.) this forest management framework does not affect a forest’s carbon-cycle neutral- are 82% of coal-fired emissions per mega- at reducing overall GHG emissions. Ac- ity, but overall carbon benefits will be un- joule of electricity produced. If biomass is counting should (1) accurately characterize derestimated if harvested wood products considered a renewable resource such that atmospheric consequences of reducing the and their substitution effects are not taken emissions represent prior uptake, burning flow of fossil fuel emissions by using biofuels into account. LCI and LCA occur within biomass to generate electricity produces 4% and (2) measure the effects on the forestland defined system boundaries. Substitution oc- of the emissions of a coal-fired power plant. base in terms of growing stock and soil car- curs when one product is replaced by an- The net biomass bar in Figure 5-4 as- bon. The assumptions and boundaries for other product and the comparison is be- sumes that the biomass was produced in an analyzing the GHG emissions of bioenergy tween the LCIs within each boundary. An area where forest carbon stocks remain stable are critical to the resulting conclusions and example would be the comparison between over the long term. Some assume that har- must be clearly understood when studies are steel joists and engineered I-joists that are functionally equivalent. There are also vesting causes a reduction in forest carbon used to justify policies or regulations. stocks, and particularly soil carbon, relative displacement factors when biofuel is used to a scenario where the biomass is not used Determination of Carbon instead of fossil fuel for manufacturing that for energy, creating a carbon debt that must occurs inside the system boundary. The dis- be overcome before the forest biomass– Neutrality placement occurs inside the system bound- based system yields net benefits (e.g., Analyses of the benefits of forest-based ary of a particular product and forms part of Schlamadinger et al. 1995, Searchinger et al. products and systems should incorporate its LCI. 2009). Such thinking is based on initia- spatial and temporal boundaries appropriate Figure 5-5 integrates harvested wood tion of measurement and comparison at the for forestry and forest products. Forest man- products and substitution benefits for the point of harvest. agement practices may be applied at the in- forest management regime in Figure 5-3b to Whether and how biomass is included dividual stand or project level, but wood provide the landscape context. It is based on in emissions accounting affects policies aimed supply systems involve large areas managed current patterns of wood use from harvested

S32 Journal of Forestry • October/November 2011 (supplement) sites across a landscape that support a viable forest industry. It does not include increased recovery of forest residuals for bioenergy use, which would offset more fossil fuel and increase the slope of the graph. In Figure 5-5 the displacement is the amount of carbon benefit that accrues from using biofuel in place of natural gas for drying of the long- lived products produced in the Inland Northwest. Displacement can be larger in other regions where fossil fuels comprise a greater share of the energy used to generate electricity or where more wood waste is used for energy. In this case from the Inland Northwest, the analysis incorporates LCI data on mill drying and the high percentage of nonfossil electricity generation in the re- Figure 5-4. Comparison of GHG emissions from electric power plants. (Source: Adapted gion caused by extensive hydroelectric re- from Lippke et al. 2011.) sources. Note that the total emissions (including biofuel emissions) resulting from production of these products shows up as a negative benefit in Figure 5-5, depicting the Table 5-7. Definitions of carbon neutrality. emissions associated with generating the total positive carbon benefits shown in this fig- Type Definition Example ure. The displacement factor above the line is the amount of equivalent fossil fuel emis- Inherent carbon neutrality Biomass carbon was only recently All biomass is “inherently carbon sions that were avoided by using biomass in removed from the atmosphere; neutral” place of natural gas for drying. The displace- returning it to the atmosphere merely closes the cycle ment factor takes into account the differen- Carbon-cycle neutrality If uptake of carbon (in CO2) by plants Biomass harvested from regions tial in burning efficiency between natural gas over a given area and time is equal to where forest carbon stocks are and biomass. emissions of biogenic carbon stable is “carbon-cycle neutral” attributable to that area, biomass As this example shows, where forest op- removed from that area is carbon- erations do not exceed the forest’s ability to cycle neutral regenerate, the gains from forest manage- Life-cycle neutrality If emissions of all greenhouse gases Wood products that store from the life cycle of a product atmospheric carbon in long-term ment are seen in carbon pools and offsets system are equal to transfers of CO2 and permanent storage equal to outside the forest, without a decline in forest from the atmosphere into that (or greater than) life-cycle carbon storage. The forest is carbon-cycle product system, the product system emissions associated with neutral in its own right; all products re- is life-cycle neutral products are (at least) “life-cycle neutral” moved from it are additional carbon sinks as Offset neutrality If emissions of greenhouse gases are Airline travel by passengers who long as they are in use, and the substitution compensated for by using offsets purchase offset credits equal to benefits of using wood in place of compara- representing removals that occur emissions associated with their outside of a product system, that travels is “offset neutral” ble building products or energy sources also product or product system is offset accrue. If a change in forest operations (e.g., neutral shorter rotations, high natural mortality Substitution neutrality If emissions associated with the life Forest-based biomass energy cycle of a product are equal to (or systems with life-cycle emissions without salvage, and reduced stocking be- less than) those associated with likely equal to (or less than) those cause of climate shifts) causes a decline in substitute products, that product or associated with likely substitute forest carbon storage, the slope of the graph product system is (at least) systems are (at least) changes and the forest itself is no longer substitution neutral “substitution neutral” Accounting neutrality If emissions of biogenic CO2 are The US government calculates carbon-cycle neutral. Maintaining or en- assigned an emissions factor of zero transfers of biogenic carbon to hancing forest productivity so that a contin- because net emissions of biogenic the atmosphere by calculating uous flow of products can come from the carbon are determined by calculating annual changes in stocks of changes in stocks of stored carbon, carbon stored in forests and forest forest provides the greatest carbon mitiga- that biogenic CO2 is accounting products; emissions of CO2 from tion benefit. neutral biomass combustion are not The forest is only the first tier. Making counted as emissions from the energy sector nor are emissions products that displace fossil fuel–intensive from decay of dead trees in the products provides a cumulative offset by re- forest counted as emissions in the ducing fossil fuel emissions and delivers the forest sector largest carbon benefit (Eriksson et al. 2007, Source: NCASI (2011). Lippke et al. 2010). Discussions about base-

Journal of Forestry • October/November 2011 (supplement) S33 ities that alter long-term average carbon stocks). The end point for the accounting may extend through the end of life of the product (World Resources Institute/World Business Council for Sustainable Develop- ment 2011). Life-cycle studies often combine all flows of GHGs to and from the atmosphere into a single number reflecting the total effects over a product’s life cycle. It may be important, however, to understand the timing of removals and emissions, particularly if comparing forest-based and substitute products or comparing alternative uses for land. Such comparisons may show short-term benefits attributable to delayed harvesting, but over time, these benefits diminish and Figure 5-5. Carbon trajectories under sustainable management of a forested landscape (as eventually cease as forests age and natural shown in Figure 5-3b). (Source: Oneil and Lippke 2010.) emissions approach uptake. The benefits associated with using products from forest- lines and additionality are about who gets spheric system, focusing on these transient based systems, however, often continue to the credit. Likewise, discussions about leak- conditions instead of the long-term balance accumulate (Schlmadinger and Marland age are about where it occurs in the global between growth and removals can lead to 1996, Lippke et al. 2010, 2011). Extending economy. These concepts are relevant in the different conclusions about the costs and the period of analysis through multiple rota- marketplace but irrelevant for climate benefits of harvested biomass and wood tions can be critical to understanding the change mitigation because if, for example, a products. short-term and long-term implications of construction company does not use wood, it The temporal scale of an analysis can be using forest-based products. will likely use a competing product with a important in several other ways, especially as Temporal considerations can also be higher carbon footprint. These market fac- it affects biomass carbon accounting. The important when discounting is used to re- tors are explored in Section 6. time period for accounting may be expanded flect the time value of emissions and reduc-

Even where growth and removals are in to include flows of CO2 into trees; CO2 tions (Levasseur et al. 2010). Such studies long-term balance, carbon stocks can fluctu- emissions from decomposing biomass in the are the norm in the physical models used in ate across the wood supply area. Although forest; and emissions associated with estab- climate modeling but are relatively uncom- the timing of year-to-year carbon fluxes can lishing, growing, or regenerating the forest mon in life-cycle studies and policy-related affect the radiative forcing of the atmo- (including land-use change and other activ- work.

S34 Journal of Forestry • October/November 2011 (supplement) section 6

Forest Carbon Policies

olicies to increase the benefits of for- projects where the value was based on mea- • Carbon pools—protocols typically est carbon can use a range of strate- surable increases in forest carbon stocks credit carbon sequestered in one or more P gies. At the national level, the quan- compared with a no-project scenario. carbon pools. The definitions and required tity of greenhouse gases (GHG) emitted can Forestry offset projects generally can be measurement method of these carbon pools be reduced by: classified into one of the following five cate- differ greatly among protocols. Typical car- • increasing net carbon sequestration gories based on adaptations of Helms’s (1998) bon pools include measurable aboveground rates in forests, and the Florida Department of Environmental biomass, estimated belowground biomass and • using wood products rather than en- Protection’s (Stevens et al. 2010) definitions. soil carbon, and some harvested wood prod- ergy- and emissions-intensive building Not all categories are recognized by the various ucts. Most project protocols do not credit products, and protocols governing forestry offset projects, wood biomass initially used for energy or the • converting forest residues into energy. and in some cases the definitions overlap. future storage of woody biomass in landfills, • Afforestation—establishing forests Voluntary carbon management pro- even though these uses are calculated as cli- where the preceding vegetation or land use grams for individuals and groups of land- mate benefits in national emissions reports. was not forests. owners have been promoted in the United • Crediting period—the crediting pe- • Reforestation—the reestablishment States, and countries that ratified the Kyoto riod specifies the time frame within which of forest cover after the previous forest was Protocol have introduced their own pro- credits for sequestered carbon may be issued removed. grams. Although the Chicago Climate Ex- from a specific project. • Forest management—management change (CCX) suspended activity in No- • Leakage—a project’s carbon benefits of existing forests to meet specified goals and vember 2010 and no federal cap-and-trade can be canceled out by activities elsewhere. objectives while maintaining forest produc- legislation that would include forest carbon Internal leakage occurs if an owner increases tivity. projects was enacted in 2010, there are vol- harvests on portions of its lands to replace • Forest conservation—management untary systems, regional programs (North- timber restricted from harvest under the off- and protection of existing forests to avoid east Regional Greenhouse Gas Initiative and set project. External leakage occurs outside conversion to nonforested land uses. Western Climate Initiative), and a state pro- the firm’s sphere of operations and occurs at • Forest preservation—management gram (in California) that could evolve into a regional, national, or global scale. and protection of existing forests to avoid more significant schemes. In other countries • Permanence and reversals—carbon degradation into less productive conditions. with temperate forests, increased demand sequestered by an offset project, particularly and prices for woody biomass used for en- Protocols for those project types typi- if credits are issued, should remain seques- ergy across Europe (European Union 2009) cally include the following elements, but the tered long enough to equal the atmospheric and the creation of carbon property rights requirements may differ significantly (Pear- effect of an emission. Based on IPCC defi- for post-1990 plantations in New Zealand son et al. 2008): nitions (Forster et al. 2007), 100 years of (New Zealand Government 2011) could in- • Eligibility—for forestry offset proj- new terrestrial carbon storage is considered a spire US incentive programs for landowners ects, many of the eligibility criteria (e.g., permanent offset for an emission of an equal to manage for forest-based climate benefits. landownership, commercial harvesting, and quantity of carbon dioxide. A reversal occurs use of pesticides) are not directly related to if carbon sequestered and credited during a Forest Carbon Offset Projects climate benefits. project’s lifetime is lost, typically to natural Forest carbon offset projects started as a • Carbon sequestration calculation pro- disasters such as wildfires or storms but also way to finance projects to reduce tropical cedures—methods to determine the num- to deliberate acts such as timber theft. deforestation with voluntary investments ber and timing of carbon credits earned Forestry offset protocols (see Box next from electric utilities (Dixon et al. 1993). throughout the life of an offset project in- page) have been created to serve several Many US consumers interested in mitigat- clude volume equations, growth-and-yield different purposes. Some are part of cap- ing climate change also preferred forest- tables, and direct measurements of standing and-trade programs, whether mandatory or based projects offered by voluntary offset forest biomass. voluntary. Others are part of emissions re- schemes (Niemeier and Rowan 2009). The • Baseline requirements—carbon cred- duction schemes. Still others were developed concept of offsets is that individual emitters its are earned for carbon sequestered above independently but have been adopted by can compensate for their carbon emissions and beyond a baseline, which may be fixed one or more programs: with carbon sequestered by qualifying proj- to a certain year, based on the national trend, • Mandatory GHG reduction pro- ects. The protocols for forestry carbon offset or defined as the “without project” scenario grams—caps are imposed on GHG emis- projects vary; most offset sales have been for or business-as-usual (BAU) case. sions. If emissions are tradable, polluters can

Journal of Forestry • October/November 2011 (supplement) S35 tocol and its baseline approach. Differences Accounting Issues Examples of Offset Programs can be further compounded by leakage, per- Additionality and Baseline Set- Mandatory cap-and-trade systems manence, and buffer requirements. The sub- tings. With reduction in GHG emissions to • Clean Development Mechanism (CDM), stantial ranges in creditable carbon gener- the atmosphere as the goal, the net amount www.cdm.unfccc.int ated have a dramatic effect on the financial of carbon sequestered must be additional to • New South Wales Greenhouse Gas Re- viability of carbon offset projects compared what would have occurred without the offset duction Scheme, www.greenhousegas. with BAU timber management scenarios. project. For forest projects, additionality is rel- nsw.gov.au/default.asp When six different protocols were applied to atively easy to establish when new trees are • New Zealand Emission Trading Scheme, www.climatechange.govt.nz/emissions- the same southern pine plantation in a study planted and maintained but considerably trading-scheme/ by Galik et al. (2009c), break-even carbon more difficult to establish when based on a • Regional Greenhouse Gas Initiative prices ($/tCO2e) had a 20-fold range de- counterfactual assertion (e.g., “I was going to (RGGI), www.rggi.org. pending on the protocol’s rules about base- harvest in 10 years but instead will wait 30 • California AB 32 Scoping Plan’s Cap- line values, reversals, leakage, and uncer- years”). This is further complicated when proj- and-Trade Program (2012 start date) tainty. Most of the break-even prices were ect guidelines are designed by the project pro- Voluntary cap-and-trade systems far above the best 2010 value for voluntary ponent, and the underlying documentation is • Chicago Climate Exchange (CCX), carbon offsets, $10/tonne of CO2 (equiva- not audited by any official regulator, as would www.chicagoclimatex.com (suspended in lent to $8/green tonne of stumpage). be required for a real estate or stock transac- 2010) The costs associated with establishing tion. A carbon baseline must be established Voluntary emissions offset protocols and maintaining forestry offset projects also against which the net change in carbon stocks • American Carbon Registry (ACR), www.americancarbonregistry.org vary depending on verification requirements, is measured so that emissions reduction credits • Climate Action Reserve (CAR), www. carbon measurement procedures, monitor- can be quantified, verified, and registered. climateactionreserve.org ing frequencies, and third-party certifica- Baseline carbon values of forest inventories are • The GHG Protocol for Project Ac tion. Per hectare, costs for the high-cost determined through standard forestry biomet- counting and the Land Use, Land-Use protocol may be five times greater than for the ric methods that include direct and statisti- Change, and Forestry Guidance for low-cost protocol (Galik et al. 2009b). Trans- cally designed and modeled measurement GHG Project Accounting, www.ghg action costs for small ownerships (less than 100 techniques, but projections into the future protocol.org • Voluntary Carbon Standard (VCS) ha) were 10–20 times more costly per offset may require numerous assumptions. The Program, www.v-c-s.org credit than for larger ownerships. Differences baseline carbon value of wood products and in transaction costs for large ownerships wood energy that are used outside the proj- (greater than 10,000 ha) are still large but are ect are typically based on a study by Smith et minor in absolute terms (less than $1.20/ha) al. (2006). However, the Smith et al. (2006) purchase benefits from certified projects or because of economies of scale. estimates of the amount of wood still in use other polluters that have reduced their emis- Under regional and state programs, the are considerably lower than the sawmill effi- sions more than required. Among countries number of voluntary projects exceeds the ciency estimates of Smith et al. (2009) and that ratified the Kyoto Protocol, New Zealand number of projects with sales. As of the end the product lifetime estimates of Skog and New South Wales (Australia) have credits of 2010, no afforestation or reforestation (2008). The practical effect of using the generated from plantation forestry, and some forestry projects had been registered with Smith et al. (2006) estimates is to increase developing countries host Clean Develop- the Northeast Regional Greenhouse Gas the apparent carbon benefits of reducing ment Mechanism afforestation projects. Initiative (RGGI), Inc. (RGGI 2011), and current harvests. The potential to exaggerate • Voluntary cap-and-trade systems— just three conservation-based forest manage- the net climate benefits of a forest offset participation is voluntary; however, partici- ment and improved forest management project will be increased if it is assumed that pants are obligated to reduce their GHG projects had offset sales following protocols wood used for energy results in a direct loss emissions. As in mandatory cap-and-trade sys- approved by the California Air Resources of carbon without any fossil fuel substitu- tems, unused quotas or credits from offset Board (Climate Action Reserve [CAR] tion benefit. projects can be purchased to meet the cap. The 2011). Since less than 20% of credits in Cal- Additionality can be controversial be- demise of the CCX means that as of 2011, ifornia have been retired after offsetting an cause new activities earn credits whereas iden- there are no voluntary systems in operation. emission (CAR 2010), it would appear that tical activities initiated in the past do not. • Voluntary emissions offset proto- many purchasers are assuming that some of Thus, additionality sometimes rewards late cols—various organizations have developed the credits will be grandfathered in future entrants while appearing to punish those who rigorous standards for offset projects. These mandatory systems. This pattern has also have historically engaged in the desired be- protocols are usually independent of any re- been noted in international carbon markets havior. Additionality is also controversial be- quirement to reduce GHGs. (United Nations Economic Commission for cause determining the counterfactual often Europe/Food and Agriculture Organization requires judgments regarding motivation. Variation among Protocols 2010). As of 2011, uncertainty about ac- US registries and programs use BAU The amount of carbon credits gener- ceptable methodologies for measuring forest and base-year approaches. The BAU base- ated under protocols used in the United carbon and related climate benefits has sig- line is the emission that would have hap- States can differ dramatically for the same nificantly limited interest in developing for- pened without any new technologies or project (Galik et al. 2009c), depending on est carbon projects that involve large up- actions. This scenario works well for com- the sets of carbon pools allowed by the pro- front costs (Waage and Hamilton 2011). paring existing and improved technologies

S36 Journal of Forestry • October/November 2011 (supplement) but is often less useful for land-based seques- leakage. Market leakage is often underesti- also critical in addressing concerns about re- tration practices, where natural ecosystem mated at the project or regional level in the versals and permanence. dynamics and future market-based actions United States because alternative wood sup- Estimates of Forest Carbon Flux. Car- increase the uncertainty of any projection. plies may come from other regions or na- bon stocks in the forest sector do not directly Changing forest management objectives, tions. As noted in Section 2, domestic pro- affect atmospheric GHG levels; rather, car- markets for alternative land uses, timber duction has fluctuated around 300 million bon flux, typically assessed as a change in prices, and ecosystem service prices (e.g., the m3 of wood products since 1980 while con- carbon stocks, is what matters in evaluating price of sequestered carbon, wildlife habitat sumption continued to increase (Smith et al. the contribution of forests. The change in acres, and water yields) all contribute to a 2009). When Murray et al. (2004) modeled carbon flux, relative to a baseline or BAU high level of inherent uncertainty when a the large reduction in timber harvests from scenario, is therefore the relevant metric. For BAU baseline is defined. Unlike the baseline public lands in the Pacific Northwest in the tracking flux at broad (state and regional) emissions of a direct emitter of CO2 (e.g., a 1990s, they estimated a market leakage rate scales and for generating baseline reference coal-fired power plant), which can be pre- of more than 80% as timber demand was values, comprehensive forest inventories based cisely measured and operationally con- met through harvests elsewhere in North on remeasured, permanent, sample plots pro- trolled, forest BAU baselines are difficult to America. Underestimating market leakage vide the most accurate and precise estimates. establish at the project level. rates will proportionally overestimate the However, such inventories do not measure In the base-year approach, an inventory global climate benefits of forest offset proj- woody carbon, biomass, or even volume. In- is taken at the beginning of the project pe- ects. However, most project-based forest stead, they assess forest area, enumerate and riod, and a second inventory is conducted offset protocols ignore market leakage alto- track live and dead trees, and measure tree some years later, using the same inventory gether, allow the project proponent to circumference and assess tree height. Some design. The net change in carbon stocks (of choose the leakage rate, or set a maximum inventories also sample down wood, litter, all allowable carbon pools within the forest market leakage rate of 20%. soils, and understory vegetation. offset project) represents the carbon seques- Temporal and Spatial Boundaries. Getting from those data to estimated tration related to the forest for that period The spatial and temporal boundaries for carbon stock involves several sources of er- and is the basis for the number of carbon carbon accounting in offset programs are ror: measurement, sampling, model, and credits issued. In a sustainably managed very program-specific. In offset programs, model selection. Commitment to quality forest, this net change in carbon stocks will selection of these boundaries is closely related assurance—as practiced, for example, by the reflect forest management actions, such as to the leakage and permanence issues discussed Forest Inventory Analysis Program (Pollard harvesting, treeplanting, and fertilizing. It previously and based on a combination of sci- 2005)—can control measurement error. will also reflect effects of natural events such entific and policy considerations. Because pro- Sampling error can be controlled by increas- as weather, wildfire, insects, and disease. grams have different policy priorities, these ing sample size, which typically does not in- Reversals and Permanence. If forest boundaries vary considerably, even for seem- troduce bias as long as the sample is repre- carbon credits are used to permanently offset ingly similar project types. sentative. Model error, the uncertainty not industrial emissions, the forest project must Spatial boundaries are usually deter- explained by the variables included in a establish permanence by ensuring an equiv- model, can be accounted for when modeling alent amount of new carbon storage over mined based on the scale of the offset proj- time. Because of the unpredictability of ect, the jurisdiction of the program author- error propagation (e.g., Phillips et al. 2000) wildfires, insect infestations, and weather, ity, and, to some extent, the need to prevent as long as model authors report error infor- permanence is typically achieved through leakage. Accordingly, spatial boundaries mation. However, model selection error can insurance mechanisms to guarantee that any vary considerably. In principle, the bound- introduce substantial bias and cannot be re- losses will be compensated. Some registries aries of the accounting should extend to all solved without investing in improved inven- and programs require that any released car- areas potentially affected by the offset proj- tory technology and/or models on a scale not bon be included in the net change calcula- ect activity, but as a practical matter, spatial previously contemplated. tions so that credits previously issued can be boundaries are usually extended only to Model selection error arises from the paid back; no additional credits can then be those areas directly affected by the project. need to estimate carbon stores for each live issued until the net change in carbon stocks Under normal circumstances, therefore, tree by selecting from thousands of arguably is again positive. Various mechanisms are boundaries extend only as far as needed to plausible, analytically defensible computa- typically used to address permanence for address direct benefits and internal leakage. tion pathways generated from different land use, including deed restrictions on land Limiting the boundaries in this manner risks combinations of published biomass, vol- use, long-term or permanent conservation missing important indirect benefits and ume, and density equations for whole trees, easements, buffers, and reserve pools (whereby large-scale leakage. boles, branches, and bark, based on dbh portions of the carbon sequestered are held in Temporal boundaries in offset pro- alone or dbh and height. Under the most reserve to offset potential losses). Insurance is grams also vary significantly. For forest- optimistic scenario of a sensitivity analysis of another approach to guaranteeing that the based projects, however, the temporal live-tree carbon stores in northwest Oregon, promised climate benefits materialize. boundaries are especially significant, e.g., in model selection error (half the prediction Market Leakage. In the forest climate selecting and modeling baseline conditions; range expressed as a percentage of the pre- project literature, meeting consumer de- as noted previously, the baseline can have diction envelope midpoint) was Ϯ37% mand with new purchases from outside the dramatic effects on the estimated benefits of (Melson et al. 2011). Given that sampling project boundary is referred to as market offset projects. Temporal boundaries are error for the same analysis implied a 95%

Journal of Forestry • October/November 2011 (supplement) S37 confidence interval of 6%, model selection pieces taken by two inventory crews even in plots as described previously. Sampling error accounts for most uncertainty in carbon stores. the same season agreed only 26–57% of the is not a factor, because remote sensing takes In most cases, carbon flux is a small time, and the lengths of coarse wood pieces a census rather than a sample of the forested fraction of carbon stocks and can be far agreed only 72% of the time; in both cases, landscape. Nevertheless, modeling carbon smaller than the error of estimated carbon “agreement” was defined as within a Ϯ20% stores directly from spectral imagery or SAR stocks. When flux is calculated as a differ- tolerance. Estimating carbon flux from soil has limitations: (1) saturation of the re- ence in carbon stocks, the error of the differ- can be problematic due to sampling and sponse signal in stands with dense canopies ence can exceed the estimate of flux. An measurement costs as well as horizontal and and high biomass (Lefsky et al. 2002); (2) analysis of Canada’s managed forests esti- vertical variability, even at the plot scale; ac- little if any direct response signal from tree mated annual net forest carbon fluxes of curate flux is not possible because the soil boles, the vegetation component containing Ϫ2 Ϯ 20 teragrams (Tg) of C/year from sample is removed from the ground and the most biomass; and (3) inability to consis- 1990 to 2008 (Stinson et al. 2011). A study therefore cannot be remeasured the way a tently detect changes in understory trees, down of carbon balance in European forests that tree can be remeasured. wood, and herbaceous cover under dense can- used estimates based on ecological site stud- These challenges to obtaining accurate opy. These deficiencies partly explain recent ies, national forest inventories, and vegeta- estimates of forest carbon flux at broad scale enthusiasm over using LiDAR (Light Detec- tion models calculated standard errors, not apply equally to obtaining estimates at the tion and Ranging systems) (e.g., Wulder et accounting for model selection error, rang- stand or project scale, e.g., to establish a al. 2010); unfortunately, LiDAR acquisition ing from 21 to 133% of estimated flux project baseline or show a change in carbon at a coverage density suitable for character- (Luyssaert et al. 2010). The current “sys- stores or flux. Additional challenges include izing forest carbon is prohibitively costly. tems” in place for estimating forest carbon ensuring a representative sample, obtaining Remote-sensing estimates of carbon flux are grossly inadequate and do not fully sufficient sample size to control sampling er- stocks remains attractive because of its ap- use the data that is available. The error esti- ror, and the need to model the carbon im- parently low cost, spatially comprehensive mates are generated via an entirely ad hoc pacts of prospective management alterna- coverage, and perhaps the deterministic re- approach that omits what is likely the great- tives (e.g., BAU versus an offset project). sult—uncertainty information is essentially est component of error (model selection). Unless vigorous effort is invested in avoiding never carried along with pixel-level or ag- For example, a US EPA (2010) report found subjectivity in plot placement (both in terms gregated estimates (for example, as standard uncertainty of Ϯ20% in estimates of forest of which stands are selected for sampling errors incorporating measurement, model, ecosystem carbon flux and Ϯ25% in esti- and where the samples are collected from and model selection errors); indeed, it would mates of harvested wood products carbon sampled stands) and in assuring that stand be hard to know how to do so in a meaning- flux. However, the Monte Carlo–based er- edges are sampled with appropriate proba- ful way, but this does not mean that the un- ror simulation used to predict uncertainty bility, inventories built on stand or compart- certainty does not exist. When no uncer- accounted primarily for sampling and model ment “exams” often exhibit sample location tainty is recognized, however, it is easy to error and did not address model selection bias that compromises representativeness. assume that stock change can be legitimately error (Smith and Heath 2000). This is especially true when the stakes in the computed by comparing modeled stocks at Especially under disturbance regimes, it outcome of the inventory are high (such as different times. In fact, even seemingly large can be important to understand carbon flux refunding carbon offset payments if prom- differences may not be real, and even the from pools other than live trees, because ised sequestration cannot be proven): sam- best validation results (typically for over- these other pools contain 65–100% (for a pling results could easily be manipulated by story trees) show models explaining barely nonstocked stand) of total ecosystem carbon plot placement or, conversely, by manage- 70% of the variation; for subcanopy carbon (Van Miegroet et al. 2007). Obtaining accu- ment activity being different at plot loca- components, such as down deadwood and rate estimates of nonlive tree pools, however, tions than elsewhere. Given the large num- snags, there is virtually no relationship be- can be especially challenging. For instance ber of plausibly valid carbon calculation tween model predictions and field-observed tracking down wood over long time intervals pathways, there is ample opportunity for values (e.g., Wimberly et al. 2003). in an extensive forest inventory still is not “equation shopping” to generate the greatest Clearly, numerous challenges exist in feasible because no system of accounting offset value. developing suitably accurate estimates of for components of change, analogous to The considerable cost of implementing carbon flux in forest-based carbon offset growth, removals, and mortality of standing a comprehensive, systematic inventory de- projects for supporting investment decisions trees, has been developed; the few studies, to sign at project scale has driven some to pro- (e.g., McKinley et al. in press). Offset pro- date, have involved only small areas and pose relying instead on remotely sensed esti- grams must recognize these limitations, pro- short time intervals and required substantial mates of forest carbon flux for monitoring viding mechanisms that protect against effort (e.g., Vanderwel et al. 2008). More- (e.g., Ahern et al. 1998, Running et al. claims of benefits or assignments of liabili- over, the density of standing and down 1999). Carbon storage has been estimated ties that are artifacts of uncertainties in esti- wood is unpredictable, and questions re- via spectral imagery (Law et al. 2006, Black- mates of carbon stocks and flux. main about the ability to develop estimates ard et al. 2008, Powell et al. 2010) and syn- Improvements in measurement and of flux from estimates of deadwood for the thetic aperture RADAR (SAR) (Bergen and sampling methods are needed. Although same plot at two points in time (Woodall Dobson 1999) from satellite and airborne measurement and sampling error are rela- and Monleon 2008). The difficulties are il- platforms. These approaches have relied on tively manageable for generating estimates lustrated by Westfall and Woodall (2007) “ground truth” of the same carbon estimates of live-tree carbon stocks and fluxes at broad who found that measurements of fine wood modeled from vegetation assessed on field scale, there are important opportunities to

S38 Journal of Forestry • October/November 2011 (supplement) improve the models that transform inven- cially if these disclosures differentiate be- tails adaptation to and mitigation of these tory measurements into estimates of carbon tween emissions that recirculate atmo- effects (Malmsheimer et al. 2008). Changes flux. Existing allometric equations (volume spheric carbon and emissions that add to in planted species selection, silvicultural and biomass of all tree components) need to atmospheric carbon. Importantly, informa- treatments, fire regimes, and insect damage be evaluated for their validity for different tion disclosure requirements are often polit- must be accounted for when projecting for- populations of trees (e.g., across geography, ically and socially more acceptable than reg- est carbon dynamics. Third, the uncertain- species, site classes, and diameter ranges) ulatory programs that mandate behavior ties present risk management problems. A and, undoubtedly, many more need to be modifications. central question is how to strike a smart developed. The transportability of models • Building codes and procurement balance between in-forest sequestration by and model forms across forest types also policies—substituting wood products for managing for increased carbon density needs evaluating, because a poor match be- steel, aluminum, concrete, plastic, and other across all forest carbon pools, and use for tween models and actual trends could over- materials permanently reduces GHG emis- bioenergy that offsets fossil fuel use and the sions (see Section 5). Local government pol- predict the level of benefits and promote du- removal of carbon to long-term sequestra- bious projects (Bottcher et al. 2008). A icies, such as building codes and procure- tion in harvested wood products and landfill critical question will be whether it is possible ment policies, which encourage or require storage (Matthews and Robertson 2005). to achieve these and other improvements in the use of life-cycle assessments on the car- The near certainty of eventual disturbance measurement and sampling methods and bon consequences of material choices, can makes dependence on in situ carbon storage quantitative risk assessments at a sufficiently have significant climate change and energy low cost to avoid the situation where achiev- benefits. sinks a high-risk alternative in many areas ing levels of accuracy comparable with those Those alternative policy approaches do (Galik and Jackson 2009). required for regulated financial transactions not require the precision in forest carbon The most effective management strate- exceeds the total financial value of forest accounting needed in offset programs. Us- gies to satisfy multiple economic, environ- management projects. Policy alternatives to ing life-cycle analyses, numerous scientific mental, and societal objectives will vary offsets that avoid the expensive imperative studies have already determined the rela- from site to site. There is substantial litera- for high accuracy measurement of flux while tive carbon benefits of various products and ture developing around management and still achieving climate benefits include, for processes, including forest biomass–based mitigation practices that maximize land- example, “bonus payments” for treeplanting products; thus there is no need to quantify scape-level ecosystem carbon stocks while or carrying higher tree stocking or permit the carbon benefits in each application of considering uncontrollable disturbances and waivers for sanitation/salvage prescriptions those products. sustain or increase carbon sequestration in aimed at capturing carbon benefits from wood and bioenergy products that achieve mortality via substitution. Managing Forest Carbon fossil fuel substitution benefits (Hines et al. Benefits and Risks 2010). Other approaches could maximize Policy Alternatives to Offsets The capacity of US forests to sequester product and energy benefits while putting Science-based forest carbon policies carbon over the next 100 years is subject to less emphasis on the levels of ecosystem car- should be part of a comprehensive energy powerful, disruptive forces: climate change; bon stocks. A major challenge for the future policy to achieve energy independence and development pressure; conversion of forest- will be ensuring policy and market environ- deliver carbon benefits while providing en- land to nonforest uses; and likely expansion ments that promote the application of strat- vironmental and social benefits, including of exotic plants, insects, and pathogens. At egies best suited to specific circumstances. clean water, wildlife habitat, and recreation. the same time, political imperatives for clean If bioenergy is to contribute to climate Economic incentives—in the form of tax energy will drive production of energy from mitigation, the bioenergy sector will need to credits, subsidies on required reforestation biomass, including forest biomass. We can expand. How this changes demand for forest inputs, or direct payments for easily measur- expect concerted efforts to mitigate climate products depends on renewable energy pol- able attributes (e.g., forest cover)—can en- change by increasing the carbon in US for- icies, the treatment of bioenergy in climate courage forest landowners to retain their forests and using wood-based energy and prod- policies, and the relative cost of producing ests as forests and manage their forests for ucts. All this will occur against a backdrop of energy from forest biomass versus other re- carbon benefits. Markets and economic incen- intense international competition among newable energy sources and fossil fuels. De- tives are powerful tools; however, two other companies that make traditional and non- effective policy mechanisms have promise. traditional forest products. veloping more efficient forms of bioenergy, • Information disclosure—The Toxic That presents several challenges for the such as combined heat and power, will also Release Inventory, Green Energy purchas- forestry sector. First, we cannot simply ex- be important. Emissions reduction benefits ing programs, and the Safe Drinking Water trapolate past forest and wood use trends to of wood energy use will vary by wood source, Act have shown that information disclosure, forecast likely futures or even apply models forest condition, the extent of forest distur- whether required by government or by pri- without accounting for the many uncertain- bance, and geographic region. Markets and vate entities, can motivate firms to change ties. For instance, carbon accumulation rates policies will determine how much new forest their behavior. Easily understood programs will likely change with a different climate biomass is purpose grown to meet energy requiring companies to disclose their GHG and species mix, and mortality relationships goals and whether harvest residues can be emissions for processes or products could could be quite different than in the past. redirected to produce energy that offsets fos- encourage the use of forest products, espe- Second, a rational management response en- sil fuel use (Morris 2008).

Journal of Forestry • October/November 2011 (supplement) S39 conclusion

Integrating Forests into a Rational Policy Framework

orests are an integral component of for a long time after being retired from ser- strong policy driver in the United States over the global carbon cycle and may vice. Substantial volumes of wood go into the past few decades, especially in the Pacific F change in response to climate change. construction products and structures: even Coast and Northeast regions. Evidence of US forest policies can foster changes in forest during the midst of the recent “Great Reces- increasing losses to disturbances that are not management that will provide measurable sion” (2007–2009), US housing starts ex- captured in forest growth modeling and reductions in carbon emissions over time ceeded 440,000 annually. Additional wood decreasing rates of carbon accumulation in while maintaining forests for environmental is used for furniture and other products, maturing forests suggests that a strong con- and societal benefits, such as timber and which at the end of their useful lives may be servation-oriented strategy may not always nontimber forest products, vibrant rural converted to energy. Paper may go into produce significant global climate benefits. communities, clean water, and wildlife hab- long-term use (e.g., books) or be recovered The climate benefits of active forest manage- from the waste stream for energy produc- itat. Policies founded on three tenets reflect- ment are most apparent when substitution ing the stocks and flows of woody biomass in tion. Other wood—construction debris, benefits that occur in the consumer sector US forests can ensure that our forests will yard waste, unrecycled paper—winds up in are included. As we move forward with pol- produce sustainable carbon, environmental, landfills, where it often deteriorates more icy discussions regarding the many positive and societal benefits. slowly than is generally assumed. In total, the rate of carbon accumulation from wood roles of US forests at local, national, and 1. Keep Forests as Forests and products in use and in landfills was about 88 global scales, it will be imperative that objec- Manage Appropriate Forests million tonnes of carbon dioxide equivalents tive, science-based analysis and interpreta- tions are used, and that particularly close for Carbon (CO2e) in 2008, about 12% of the rate of attention is paid to assumptions underlying For more than 70 years, US forest cover sequestration in forests. the analyses. has increased and net growth has exceeded US policymakers should take to heart removals and mortality. Therefore, carbon 3. The Substitution Effect Is the finding of the Intergovernmental Panel storage is increasing in the United States. In Real, Irreversible, and some forests (e.g., old-growth), other con- Cumulative on Climate Change in its Fourth Assessment siderations and other benefits will usually Compared with steel, aluminum, con- Report when it concluded that “In the long outweigh carbon benefits. However, forests crete, or plastic products, considerably less term, a sustainable forest management strat- will change with or without management, energy, and vastly less fossil fuel–derived en- egy aimed at maintaining or increasing for- and choosing not to manage has its own car- ergy, is required to make wood products. est carbon stocks, while producing an an- bon consequences. Young, healthy forests The low embodied energy of wood building nual sustained yield of timber, fibre or are carbon sinks. As forests mature, they products, structures, furniture, cabinets, and energy from the forest, will generate the larg- generally become carbon-cycle neutral or other products has been well documented est sustained mitigation benefit” (IPCC even carbon emission sources. Net primary through life-cycle assessments. Not only is 2007a, 543). An integrated rational energy productivity declines and the decay of trees the quantity of energy used in manufactur- and environmental policy framework must killed by natural disturbances—wind- ing wood products low compared with other be based on the premise that atmospheric storms, fire, ice storms, hurricanes, insect materials, but the quantity of fossil energy is greenhouse gas levels are increasing primar- and disease infestations—emits carbon comparatively very low: one-half to two- ily because of the addition of geologic fossil without providing the carbon benefits avail- thirds of the energy used by the North fuel–based carbon into the carbon cycle. able through product and energy substitution. American wood products industry is bioen- Forest carbon policy that builds on the sci- ergy. For instance, compared with steel entific information summarized in this arti- 2. Recognize that Substantial framing with an average recycled content, cle can be an important part of a compre- Quantities of Carbon Are the manufacture of wood framing requires hensive energy policy that promotes energy Stored in Wood Products for one-half or less the total energy, and one- independence and delivers real carbon ben- fourth to one-fifth the fossil energy. Long Periods of Time efits while providing essential environmen- Wood is one-half carbon by weight, Conserving forests for recreational, aes- tal and social benefits, including clean water, and it lasts a long time in service—and often thetic, and wildlife habitat goals has been a wildlife habitat, and recreation.

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S48 Journal of Forestry • October/November 2011 (supplement) About the Task Force

Robert W. Malmsheimer Paper Science and founder and director of report, “Forest Management Solutions in Task Force Chair, and Professor of Forest Pol- the Forest Products Management Develop- Mitigating Climate Change in the United icy and Law, SUNY College of Environmental ment Institute at the University of Minne- States.” He has a BS in natural resource Science and Forestry, Syracuse, New York sota. Bowyer has a BS in forest management management from the University of Califor- Malmsheimer, a professor at SUNY from Oklahoma State University, an MS in nia–Berkeley and an MBA in international ESF since 1999, teaches courses in natural wood science from Michigan State Univer- business from the University of Phoenix; he resources policy and environmental and nat- sity, and a PhD in wood science and tech- also completed graduate work in silviculture ural resources law. His research focuses on nology from the University of Minnesota. and fire ecology at the University of Wash- how laws and the legal system affect forest ington. He has more than 35 years of diverse and natural resources management, includ- Jeremy S. Fried experience as a line and staff officer with the ing how climate change and carbon seques- Research Forester, Resource Monitoring and US Forest Service in the Washington Office, tration policies affect forest and natural re- Assessment Program, Pacific Northwest Re- two regions, six national forests, and inter- sources. Before becoming a professor, search Station, US Forest Service, Portland, national programs. Malmsheimer practiced law for 6 years. He Oregon has a PhD in forest policy from SUNY ESF, Fried has been with the PNW Research Robert L. Izlar a JD from Albany Law School, and a BLA Station’s Forest Inventory and Analysis unit Director, University of Georgia Center for For- from SUNY ESF. He is a SAF Fellow and since 1999, serving as California FIA analyst est Business, Athens, Georgia the chair of the SAF Committee on Forest since 2000 and as team leader from 1999 to Izlar has been director of the University Policy. He cochaired the 2007–2008 SAF 2009. His research focus is interdisciplinary of Georgia Center for Forest Business since Task Force on Climate Change and Carbon application of systems analysis and geo- 1998, and he teaches courses on renewable Sequestration, and he has chaired and served graphic information science to contempo- natural resources policy and consulting. He on numerous national and state SAF com- rary natural resource management issues. has 26 years’ experience in private forest in- mittees and task forces. Current and recent examples include eco- dustry, including stints as head of the Geor- nomic feasibility of landscape-scale fuel gia and Mississippi forestry associations. He James L. Bowyer treatments, forest carbon accounting, ini- has a bachelor’s and a master’s in forest re- Professor Emeritus, University of Minnesota tial attack simulation and optimization, sources from the University of Georgia and Department of Bioproducts and Biosystems impacts of climate change on wildland an MBA from Georgia Southern University. Engineering, President of Bowyer & Associates, fire, and building inventory-based models He served as SAF Georgia Division chair in Inc., and Director of the Responsible Materials of fire effects. Before joining the PNW 1995 and Oconee Chapter chair in 2010, Program in Minneapolis-based Dovetail Part- Research Station, he served on the forestry and was elected a Fellow in 2003. He is a ners, Inc. faculties at Michigan State and Helsinki fellow of the Royal Swedish Academy of Bowyer is president of Bowyer & Asso- universities. He has a PhD in forest manage- Agriculture and Forestry and is a SAF Cer- ciates, Inc., a business-oriented environment and economics from the University of tified Forester and a Registered Forester in mental consulting firm, and director of the California–Berkeley and an MS in forest Georgia. Responsible Materials Program in Minne- ecology and soils from Oregon State Univer- apolis-based Dovetail Partners, Inc., a non- sity. Fried served as the resource measure- Reid A. Miner profit focused on the effects and trade-offs ments subject area representative on SAF’s Vice President for Sustainable Manufacturing, of environmental decisions, including con- Forest Science and Technology Board and as National Council for Air and Stream Im- sumption choices, land use, and policy alter- an officer (secretary, chair-elect, and chair) provement (NCASI), Research Triangle Park, natives. Bowyer is a 27-year member of SAF of both the Management Science/Opera- North Carolina and an elected fellow of the International tions Research and GIS working groups. Miner has worked for National Council Academy of Wood Science. He has served as for Air and Stream Improvement since president of the Forest Products Society and Edmund Gee 1974. For the past 15 years, he has focused of the Society of Wood Science and Tech- USDA Forest Service National Woody Bio- on sustainability topics, including the nology, vice president of the Consortium for mass Utilization Team Leader and National connections between the forest products Research on Renewable Industrial Materi- Partnership Coordinator industry and the global carbon cycle. His als, and chairman of the Tropical Forest Gee is the past chair of the Interagency work has involved collaborations with a Foundation. He was head of the University Woody Biomass Utilization Group. He was range of organizations, including the United of Minnesota’s Department of Wood and one of the coauthors of the SAF task force Nations Food and Agriculture Organiza-

Journal of Forestry • October/November 2011 (supplement) S49 tion, the International Finance Corpora- PhD in forestry and economics from North carbon accounting into a forest manage- tion of the World Bank Group, the Inter- Carolina State University, an MBA from ment framework, ecological and economic governmental Panel on Climate Change Louisiana Tech University, an MS in resource constraints to biomass feedstock availability, (IPCC), the US Forest Service, the Environ- management from SUNY ESF, and an AB in life-cycle analysis, and timber supply analy- mental Defense Fund, the Council for Sus- biology from the University of North Caro- sis. Before her midcareer return to academia, tainable Biomass Production, the World lina. He is a SAF Fellow, a councilman from she worked as a Registered Professional For- Resources Institute, and the World Business District 11, editor of the Southern Journal of ester in both consulting and government Council for Sustainable Development. He Applied Forestry, and has served as a chair of forestry positions in several central British was a contributing author to IPCC’s Fourth the Mississippi state society and local SAF Columbia areas devastated by the mountain Assessment Report and is on US EPA’s and chapter. Munn is a SAF Certified Forester pine beetle epidemic. IPCC’s lists of expert reviewers on carbon and a Mississippi Registered Forester. accounting. Miner has BS and MS degrees William C. Stewart in chemical engineering from the University Elaine Oneil Forestry Specialist, Environmental Science, of Michigan. Research Scientist, University of Washington, Policy and Management Department, Univer- and Executive Director, Consortium for Re- sity of California–Berkeley Ian A. Munn search on Renewable Industrial Materials Stewart is a Cooperative Extension for- Professor of Forestry Economics and Manage- (CORRIM), Seattle estry specialist who has been based at UC ment, Mississippi State University, Mississippi Oneil is a research scientist at the Uni- Berkeley since 2007. He is also the director Munn has been a professor in the De- versity of Washington and the executive di- of the Center for Forestry and co-director partment of Forestry at Mississippi State rector of the Consortium for Research on for the Center for Fire Research and Out- University since 1993. He teaches the de- Renewable Industrial Materials, a 17-uni- reach at UC Berkeley. His current areas of partment’s capstone course in professional versity research consortium that conducts research and extension focus on the linkages practices, as well as a course in advanced for- life-cycle inventory and life-cycle assess- between managed forests and climate change, est management. He also coordinates stu- ments on wood products from cradle to the economic aspects of fire-adapted silvi- dent internships for academic credit. His re- grave. She has a BS in forestry from the Uni- culture in California, and succession plan- search focuses on nonindustrial private versity of British Columbia and MSc and ning with family forest owners. He has an forest landowner issues, including land- PhD degrees from the University of Wash- MS and PhD in forest economics and policy owners’ willingness to provide ecosystem ington. Her focus is on forest management from the University of California–Berkeley services, recreational opportunities, and log- operational research: the effects of harvest- and a BS in environmental earth sciences ging residues and short-rotation woody ing on bald eagle nesting, management of from Stanford University. He is active on crops for biofuels. Before pursuing his PhD Douglas-fir at the edge of its climatic range, technical committees of the Northern Cali- degree, Munn was a timberland manager for climate change impacts on forest health in fornia SAF and has served on numerous na- a forest products firm for 10 years. He has a Inland West forests, integration of forest tional and state scientific review task forces.

S50 Journal of Forestry • October/November 2011 (supplement) Subject Index

Accounting neutrality, S33t Food, Conservation, and Energy Act of 2008, S26 Greenhouse gases (GHG) Afforestation, S35 Forest, management, S35 comparison of emissions, S32f Baseline requirements, forest offset projects, S35 Forest biomass executive summary, S9 Billion Ton Report, S24 energy from, S13 forest carbon policies and, S13, S35–S39 Bioenergy, managing forests, S7 total estimated annual flux, S20t Health Forests Restoration Act of 2003, S26 Biomass Commercial Utilization Grants Program, S26 Forest biomes Inherent carbon neutrality, S33t Biomass Crop Assistance Program (BCAP), S26 area, storage, and gross photosynthesis, S21t Insects, forest mortality, S18 Biomass energy production, S30–S32 climate-related characteristics, S21–S22 Intergovernmental Panel on Climate Change (IPCC), balance and benefits, S31 forest carbon policies and, S35–S39 forest-atmosphere fluxes and, S21, S22f Biomass feedstocks, S24–S26 Kyoto Protocol, forest carbon policies, S35–S39 Forest carbon offset projects, S7, S35–S39 availability, S24 Land-use change, effects on forest carbon, S18–S19 additionality and baseline settings, S36 economics, S25–S26 Leakage, forest offset projects, S35 estimates of forest carbon flux, S37 environmental consequences and constraints, S25 Life-cycle assessment methods (LCA), S7, S27 factors that affect supply, S24–S25 market leakage, S37 Life-cycle neutrality, S33t government policy, S26 policy alternatives to, S39 MAI, definition, S15 landowner preferences, S26 reversals and permanence, S37 Mandatory GHG reduction programs, forest offset use and issues, S10 temporal and spatial boundaries, S37 projects, S36 Biomass Research and Development Act of 2000, S26 variation among protocols, S36 Market price biomass, S24 Bituminous coal, comparison of GHG emissions, S32f Forest carbon, see also Carbon Methane emissions, from wood degradation, S30 Boreal forests, S21–S23, S22f accounting, S19 Northeast Regional Greenhouse Gas Initiative, S35– Building codes and procurement policies, S39 atmosphere fluxes, S22–S23 S36 Business-as-usual case (BAU), S35–S39 dynamics, S7 Offset neutrality, S33t California Air Resources Board (Climate Action Re- fire effects, S17–S18 Performance-based biomass, S24 serve CAR), S36 flux from disturbances, S17–S19 Permanence and reversals, forest offset projects, S35 Carbon, see also Forest carbon flux in US sector in 2008, S16t Potentially available biomass, S24 Carbon accounting, S7 insects and disease, S18 Reforestation, S35 Carbon-cycle neutrality, S33t land-use change, S18–S19 Renewable biomass, definitions, S26 Carbon emissions management and capture, S15–S17 Resources Planning Act, S19–S20 determination of neutrality, S32, S33t Roundwood, US industrial, S19f managing benefits and risks, S39 floor structure, S28f Safe Drinking Water Act, S39 policies, S7, S10, S13, S35–S39 from manufacture of wood products, S27, S28t Stand-scale trajectories, S14 stocks and flows, S9, S14–S20 Carbon flux Substitution effect, S10, S11, S40 storage in wood products, S11, S27, S29f estimates by pool, US, S16–S17 Substitution neutrality, S33t from forest disturbances, S17–S19 sustainably managed, S13 Supply curve biomass, S24 US forestry sector in 2008, S16t total estimated annual flux, S20t Sustainable management Carbon framework, S11, S13, S13f trajectories, S14–S15, S16 carbon trajectories under, S34f Carbon pools trajectories under sustainable management, S34f forest carbon pools, S32f forest offset projects, S35 weather-related disturbances, S18 Technically available biomass, S24 sustainable management, S32f Forest conservation, S35 Temperate forests, S21–S23, S22f Carbon sequestration calculation procedures, forest off- Forest growth, removals, and mortality, US, S24f Tillamook Fire, Oregon Coast Range, S18 set projects, S35 Forest Inventory and Analysis (FIA), S17–S19 Timberlands, annual flux, 2006, S20f Chicago Climate Exchange (CCX), S35–S36 Forest Offset Programs, examples, S36 Tongass National Forest, S15 Climate change, disturbances and mortality, S22–S23 Forest preservation, S35 Toxic Release Inventory, S39 Climate-forest interactions, S10, S21–S23 Forest products, versus energy-intensive materials, S13 Tropical forests, S21–S23, S22f Combined heat and power systems (CHP), S30–S31 Forests Voluntary cap-and-trade systems, forest offset projects, Combustion, S30–S31 integrating into a rational policy framework, S11, S36 Coordinated resource offering protocol (CROP), S24 S40 Voluntary emissions offset protocols, forest offset proj- Crediting period, forest offset projects, S35 management, S7 ects, S36 Water fluxes, climate-forest interactions, S22–S23 Disease, forest mortality, S18 US area of land, S19t Electric power plants, comparison of GHG emissions, Weather, effects on forest carbon, S18 Forest-scale trajectories, S15 S32f Western Climate Initiative, S35 Forest soils, carbon trajectories, S16–S17 Eligibility, forest offset projects, S35 Wood energy, S30–S32 Fossil fuel-produced energy, S13 Energy, wood, S30–S32 Wood-fossil fuel substitution effects, S27–S34 Fossil fuels, S27–S34 combustion and gasification, S30–S31 Wood products substitution, S10, S31 consumption, entire structures, S28 carbon storage in, S11, S27, S40 Energy fluxes, climate-forest interactions, S22–S23 exterior wall designs, S29t emissions from manufacture, S27, S28t Energy Policy Act of 2005, S26 floor design, S29t end-of-life considerations, S28–S29 Environment, consequences of biomass use, S25 Gasification, S30–S31 fate of in solid waste sites, S30t Environmental Protection Agency’s report, forest car- Genetic tree improvement, S25 projected half-lives for end uses, S30t bon policies and, S35–S39 Global carbon pools, S13, S13f substitutions for, S7, S10, S27–S28, S40 Fire, forest carbon and, S17–S18 Green Energy purchasing programs, S39 Woody crops, S25

Journal of Forestry • October/November 2011 (supplement) S51