A systems approach to assess climate change mitigation options in landscapes of the United States forest sector

Abstract

BackgroundUnited States forests can contribute to national strategies for greenhouse gas reductions. The objective of this work was to evaluate forest sector climate change mitigation scenarios from 2018 to 2050 by applying a systems-based approach that accounts for net emissions across four interdependent components: (1) forest ecosystem, (2) land-use change, (3) harvested wood products, and (4) substitution benefits from using wood products and bioenergy. We assessed a range of land management and harvested wood product scenarios for two case studies in the U.S: coastal South Carolina and Northern Wisconsin. We integrated forest inventory and remotely-sensed disturbance data within a modelling framework consisting of a growth-and-yield driven ecosystem carbon model; a harvested wood products model that estimates emissions from commodity production, use and post-consumer treatment; and displacement factors to estimate avoided fossil fuel emissions. We estimated biophysical mitigation potential by comparing net emissions from land management and harvested wood products scenarios with a baseline (‘business as usual’) scenario.ResultsBaseline scenario results showed that the strength of the ecosystem carbon sink has been decreasing in the two sites due to age-related productivity declines and deforestation. Mitigation activities have the potential to lessen or delay the further reduction in the carbon sink. Results of the mitigation analysis indicated that scenarios reducing net forest area loss were most effective in South Carolina, while extending harvest rotations and increasing longer-lived wood products were most effective in Wisconsin. Scenarios aimed at increasing bioenergy use either increased or reduced net emissions within the 32-year analysis timeframe.ConclusionsIt is critical to apply a systems approach to comprehensively assess net emissions from forest sector climate change mitigation scenarios. Although some scenarios produced a benefit by displacing emissions from fossil fuel energy or by substituting wood products for other materials, these benefits can be outweighed by increased carbon emissions in the forest or product systems. Maintaining forests as forests, extending rotations, and shifting commodities to longer-lived products had the strongest mitigation benefits over several decades. Carbon cycle impacts of bioenergy depend on timeframe, feedstocks, and alternative uses of biomass, and cannot be assumed carbon neutral.Electronic supplementary materialThe online version of this article (10.1186/s13021-018-0100-x) contains supplementary material, which is available to authorized users.

Mitigation Impact of Different Harvest Scenarios of Finnish Forests That Account for Albedo, Aerosols, and Trade-Offs of Carbon Sequestration and Avoided Emissions

“…The results of this study demonstrate that deciding on a forest harvest scheme for producing climate mitigation requires a holistic consideration of all associated effects, and that appropriate management of boreal forests can have an important climate change mitigation role. Our results, in support of previous similar findings (e.g., EASAC, 2017;Dugan et al, 2018), should caution policy makers who are emphasizing the increased utilization of forest biomass for short-living products and bioenergy as a measure to mitigate climate change. Within the analyzed 50 years timeframe, the largest mitigation effects emerged in the scenarios where carbon stocks increased because of longer rotations.…”

“…The sink reduction due to increased wood use for bioenergy or short-living wood products like pulp and paper is not easily compensated (Ter-Mikaelian et al, 2015;Seppälä et al, 2019). Especially in boreal forests where trees grow slowly and soil carbon stock plays a major role, the time span of climate benefits from increased traditional wood use has been found to be too long (Mitchell et al, 2012;Lemprière et al, 2013;Chen et al, 2018;Dugan et al, 2018) to cope with the very limited carbon budget determined by the objectives of Paris Agreement (IPCC, 2018). Studies analyzing climatic impact of wood use show that the result depends heavily on the assumed portfolio of wood products and therefore the obtained substitution benefits (Seppälä et al, 2019).…”

Meeting GHG reduction targets requires accounting for all forest sector emissions

“…We show results with and without the substitution credit (a decrease in forest sector emissions) because it cannot be verified. We show the potential impact it has on the overall forest sector carbon sink, even though the displacement factor may be unrealistically high (Smyth et al 2017, Dugan et al 2018). For forest sector emissions assessments, the uncertainty suggests exclusion of the credit.…”

“…We assumed 75% of 'waste wood' was used for fuelwood in homes or at mills (wood manufacturing losses in table 1). We accounted for displacement of fossil fuel energy sources using a displacement factor of 0.68 assuming a mix of coal and natural gas replacement (Smyth et al 2017, Dugan et al 2018).…”

Ips typographus and Dendroctonus ponderosae Models Project Thermal Suitability for Intra- and Inter-Continental Establishment in a Changing Climate

“…Growing trees absorb carbon dioxide (CO 2 ) and can store it for hundreds to thousands of years. Increasing atmospheric concentrations of CO 2 , largely caused by industrial activities, are contributing to global climate change (IPCC, 2013) and forest carbon sequestration and storage have become important mitigation strategies (Dugan et al, 2018;Xu et al, 2018). Multiple factors affect in situ forest carbon storage capacity including tree growth and decay rates, management, and tree mortality due to deforestation and natural disturbances Allen, 2002 Li et al, 2003;Canadell and Raupach, 2008).…”