R. Birdsey’s research while affiliated with Woodwell Climate Research Center and other places

Managing forests and forest products to help mitigate climate change was quantified in three coordinated studies involving six regions within North America. Each country-specific study examined several mitigation scenarios in a comparative analysis, using harmonized tools with site-specific data and a systems approach that included forest ecosystem, harvested wood products, and substitution benefits relative to a forward-looking baseline. Here we synthesized the North American case studies by comparing normalized annual mitigation potential (net change in emissions and removals relative to the baseline), and examined differences in ecosystems and drivers that affected the ranking of mitigation activities. Considering all six study sites, the highest mitigation potential over the 32-year study period occurred in southern temperate and tropical regions where avoided deforestation, increased afforestation, and accelerated forest recovery after disturbance resulted in the greatest reduction in net emissions. The only effective scenario common to all regions was increased production of longer-lived wood products, where longer product lifetimes delayed emissions to the atmosphere, and increased substitution benefits from using wood in place of more emissions-intensive materials. We conclude that regionally differentiated mitigation scenarios that take into account diverse ecosystems dynamics and drivers offer the highest mitigation potential and a practical way to allocate resources for forestry activities.

Forests are important ecosystems that are under increasing pressure from human use and environmental change, and have a significant ability to remove carbon dioxide from the atmosphere, and are therefore the focus of policy efforts aimed at reducing deforestation and degradation as well as increasing afforestation and reforestation for climate mitigation. Critical to these efforts is the accurate monitoring, reporting and verification of current forest cover and carbon stocks. For planning, the additional step of modeling is required to quantitatively estimate forest carbon sequestration potential in response to alternative land-use and management decisions. To be most useful and of decision-relevant quality, these model estimates must be at very high spatial resolution and with very high accuracy to capture important heterogeneity on the land surface and connect to monitoring efforts. Here, we present results from a new forest carbon monitoring and modeling system that combines high-resolution remote sensing, field data, and ecological modeling to estimate contemporary above-ground forest carbon stocks, and project future forest carbon sequestration potential for the state of Maryland at 90 m resolution. Statewide, the contemporary above-ground carbon stock was estimated to be 110.8 Tg C (100.3–125.8 Tg C), with a corresponding mean above-ground biomass density of 103.7 Mg ha⁻¹ which was within 2% of independent empirically-based estimates. The forest above-ground carbon sequestration potential for the state was estimated to be much larger at 314.8 Tg C, and the forest above-ground carbon sequestration potential gap (i.e. potential-current) was estimated to be 204.1 Tg C, nearly double the current stock. These results imply a large statewide potential for future carbon sequestration from afforestation and reforestation activities. The high spatial resolution of the model estimates underpinning these totals demonstrate important heterogeneity across the state and can inform prioritization of actual afforestation/reforestation opportunities. With this approach, it is now possible to quantify both the forest carbon stock and future carbon sequestration potential over large policy relevant areas with sufficient accuracy and spatial resolution to significantly advance planning.

KEY FINDINGS 1. Net uptake of 217 teragrams of carbon (Tg C) per year by the forest sector in North America is well documented and has persisted at about this level over the last decade. The strength of net carbon uptake varies regionally, with about 80% of the North American forest carbon sink occurring within the United States (high confidence, very likely). 2. Forest regrowth following historical clearing plays a substantial role in determining the size of the forest carbon sink, but studies also suggest sizeable contributions from growth enhancements such as carbon dioxide fertilization, nitrogen deposition, or climate trends supporting accelerated growth (medium confidence). Resolving each factor’s contribution is a major challenge and critical for developing reliable predictions. 3. Annual harvest removals from forestry operations in select regions decrease forest carbon stocks, but this decline in stocks is balanced by post-harvest recovery and regrowth in forestlands that were harvested in prior years. Removal, processing, and use of harvested biomass causes carbon emissions outside of forests, offsetting a substantial portion (about half) of the net carbon sink in North American forests (high confidence). 4. Recent trends in some disturbance rates (e.g., wildfires and insects) have diminished the strength of net forest carbon uptake across much of North America. Net loss of forest carbon stocks from land conversions reduced sink strength across the continent by 11 Tg C per year, with carbon losses from forest conversion exceeding carbon gains from afforestation and reforestation (medium confidence). 5. Several factors driving the carbon sink in North American forests are expected to decline over coming decades, and an increasing rate of natural disturbance could further diminish current net carbon uptake (medium confidence). Note: Confidence levels are provided as appropriate for quantitative, but not qualitative, Key Findings and statements.

Background: We determine the potential of forests and the forest sector to mitigate greenhouse gas (GHG) emissions by changes in management practices and wood use for two regions within Canada's managed forest from 2018 to 2050. Our modeling frameworks include the Carbon Budget Model of the Canadian Forest Sector, a framework for harvested wood products that estimates emissions based on product half-life decay times, and an account of marginal emission substitution benefits from the changes in use of wood products and bioenergy. Using a spatially explicit forest inventory with 16 ha pixels, we examine mitigation scenarios relating to forest management and wood use: increased harvesting efficiency; residue management for bioenergy; reduced harvest; reduced slashburning, and more longer-lived wood products. The primary reason for the spatially explicit approach at this coarse resolution was to estimate transportation distances associated with delivering harvest residues for heat and/or electricity production for local communities. Results: Results demonstrated large differences among alternative scenarios, and from alternative assumptions about substitution benefits for fossil fuel-based energy and products which changed scenario rankings. Combining forest management activities with a wood-use scenario that generated more longer-lived products had the highest mitigation potential. Conclusions: The use of harvest residues to meet local energy demands in place of burning fossil fuels was found to be an effective scenario to reduce GHG emissions, along with scenarios that increased the utilization level for harvest, and increased the longevity of wood products. Substitution benefits from avoiding fossil fuels or emissions-intensive products were dependent on local circumstances for energy demand and fuel mix, and the assumed wood use for products. As projected future demand for biomass use in national GHG mitigation strategies could exceed sustainable biomass supply, analyses such as this can help identify biomass sources that achieve the greatest mitigation benefits.

Forests play a leading role in regional and global terrestrial carbon (C) cycles. Changes in C sequestration within forests can be attributed to areal expansion (increase in forest area) and forest growth (increase in biomass density). Detailed assessment of the relative contributions of areal expansion and forest growth to C sinks is crucial to reveal the mechanisms that control forest C sinks and it is helpful for developing sustainable forest management policies in the face of climate change. Using the Forest Identity concept and forest inventory data, this study quantified the spatial and temporal changes in the relative contributions of forest areal expansion and increased biomass growth to China's forest biomass C sinks from 1977 to 2008. Over the last 30 years, the areal expansion of forests has been a larger contributor to C sinks than forest growth for planted forests in China (62.2 % vs. 37.8 %). However, for natural forests, forest growth has made a larger contribution than areal expansion (60.4 % vs. 39.6 %). For all forests (planted and natural forests), growth in area and density has contributed equally to the total C sinks of forest biomass in China (50.4 % vs. 49.6 %).The relative contribution of forest growth of planted forests showed an increasing trend from an initial 25.3 % to 61.0 % in the later period of 1998 to 2003, but for natural forests, the relative contributions were variable without clear trends, owing to the drastic changes in forest area and biomass density over the last 30 years. Our findings suggest that afforestation will continue to increase the C sink of China's forests in the future, subject to sustainable forest growth after the establishment of plantations.

México desarrolla un sistema de medición, reporte y verificación de los flujos de gases de efecto invernadero (GEI) asociados a REDD+. Este sistema permitirá consolidar el reporte nacional de emisiones de GEI a un nivel de incertidumbre intermedio o Tier 2, a la vez de transitar hacia un menor nivel incertidumbre o Tier 3, con el uso de modelos de la dinámica del carbono e información de sitios de monitoreo intensivo del carbono. Por ello, desde el 2012 la CONAFOR coordina un esfuerzo de colaboración institucional nacional e internacional, para la compilación de información derivada de inventarios forestales, teledetección, datos de perturbación, y modelación consistente con las Guías de Buenas Prácticas del IPCC para la mejora de información sobre la dinámica del carbono forestal multitemporal y multi-espacial en México. Actualmente, se tienen resultados preliminares desarrollados para los cinco estados de Acción Temprana REDD+, usando como principal insumo al modelo CBM-CFS3 la misma información que se emplea en el enfoque Tier 2. También, se tienen resultados de pruebas para la reducción de incertidumbre en insumos y supuestos empleados. Paralelamente, se analiza información sobre reservorios y flujos de carbono derivados de la red de sitios de monitoreo intensivo, a fin de completar en julio del 2015, protocolos de medición y recomendaciones para el análisis de datos de campo tipo el Inventario Nacional Forestal y de Suelos, mejoras a las estimaciones de GEI regionales, validación de los resultados de modelación, evaluación costo-efectividad y nivel de incertidumbre, además de transferencia de información y experiencias, mediante publicaciones y el fortalecimiento de capacidades a instituciones. http://foris.fao.org/wfc2015/api/file/5547c18315ae74130aee69d5/contents/1a9551d5-d5f1-45d6-9ef0-6764f93ed4c1.pdf

México desarrolla un sistema de medición, reporte y verificación de los flujos de gases de efecto invernadero (GEI) asociados a REDD+. Este sistema permitirá consolidar el reporte nacional de emisiones de GEI a un nivel de incertidumbre intermedio o Tier 2, a la vez de transitar hacia un menor nivel incertidumbre o Tier 3, con el uso de modelos de la dinámica del carbono e información de sitios de monitoreo intensivo del carbono. Por ello, desde el 2012 la CONAFOR coordina un esfuerzo de colaboración institucional nacional e internacional, para la compilación de información derivada de inventarios forestales, teledetección, datos de perturbación, y modelación consistente con las Guías de Buenas Prácticas del IPCC para la mejora de información sobre la dinámica del carbono forestal multitemporal y multi-espacial en México. Actualmente, se tienen resultados preliminares desarrollados para los cinco estados de Acción Temprana REDD+, usando como principal insumo al modelo CBM-CFS3 la misma información que se emplea en el enfoque Tier 2. También, se tienen resultados de pruebas para la reducción de incertidumbre en insumos y supuestos empleados. Paralelamente, se analiza información sobre reservorios y flujos de carbono derivados de la red de sitios de monitoreo intensivo, a fin de completar en julio del 2015, protocolos de medición y recomendaciones para el análisis de datos de campo tipo el Inventario Nacional Forestal y de Suelos, mejoras a las estimaciones de GEI regionales, validación de los resultados de modelación, evaluación costo-efectividad y nivel de incertidumbre, además de transferencia de información y experiencias, mediante publicaciones y el fortalecimiento de capacidades a instituciones. http://foris.fao.org/wfc2015/api/file/5547c18315ae74130aee69d5/contents/1a9551d5-d5f1-45d6-9ef0-6764f93ed4c1.pdf

México desarrolla un sistema de medición, reporte y verificación de los flujos de gases de efecto invernadero (GEI) asociados a REDD+. Este sistema permitirá consolidar el reporte nacional de emisiones de GEI a un nivel de incertidumbre intermedio o Tier 2, a la vez de transitar hacia un menor nivel incertidumbre o Tier 3, con el uso de modelos de la dinámica del carbono e información de sitios de monitoreo intensivo del carbono. Por ello, desde el 2012 la CONAFOR coordina un esfuerzo de colaboración institucional nacional e internacional, para la compilación de información derivada de inventarios forestales, teledetección, datos de perturbación, y modelación consistente con las Guías de Buenas Prácticas del IPCC para la mejora de información sobre la dinámica del carbono forestal multitemporal y multi-espacial en México. Actualmente, se tienen resultados preliminares desarrollados para los cinco estados de Acción Temprana REDD+, usando como principal insumo al modelo CBM-CFS3 la misma información que se emplea en el enfoque Tier 2. También, se tienen resultados de pruebas para la reducción de incertidumbre en insumos y supuestos empleados. Paralelamente, se analiza información sobre reservorios y flujos de carbono derivados de la red de sitios de monitoreo intensivo, a fin de completar en julio del 2015, protocolos de medición y recomendaciones para el análisis de datos de campo tipo el Inventario Nacional Forestal y de Suelos, mejoras a las estimaciones de GEI regionales, validación de los resultados de modelación, evaluación costo-efectividad y nivel de incertidumbre, además de transferencia de información y experiencias, mediante publicaciones y el fortalecimiento de capacidades a instituciones.