• Energy Research

La biomasse forestière est un indicateur essentiel pour la surveillance des écosystèmes et du climat de la Terre. Il s'agit d'une contribution essentielle à la comptabilisation des gaz à effet de serre, à l'estimation des pertes de carbone et de la dégradation des forêts, à l'évaluation du potentiel des énergies renouvelables et à l'élaboration de politiques d'atténuation du changement climatique telles que REDD+, entre autres. La cartographie mur à mur de la biomasse aérienne (AGB) est maintenant possible avec la télédétection par satellite (RS). Cependant, les méthodes RS nécessitent des données in situ existantes, à jour, fiables, représentatives et comparables pour l'étalonnage et la validation. Nous présentons ici l'initiative Forest Observation System (Fos), une coopération internationale visant à établir et à maintenir une base de données mondiale sur la biomasse forestière in situ. Les estimations de la hauteur de l'AGB et de la canopée avec leurs incertitudes associées sont dérivées à une échelle de 0,25 ha à partir de mesures sur le terrain effectuées dans des parcelles de recherche permanentes à travers les forêts du monde. Toutes les estimations des placettes sont géolocalisées et ont une taille qui permet une comparaison directe avec de nombreuses mesures RS. Le Fos offre le potentiel d'améliorer la précision des produits de la biomasse à base de RS tout en développant de nouvelles synergies entre la RS et les communautés de recherche sur les écosystèmes terrestres. La biomasa forestal es un indicador esencial para monitorear los ecosistemas y el clima de la Tierra. Es un insumo crítico para la contabilidad de gases de efecto invernadero, la estimación de las pérdidas de carbono y la degradación forestal, la evaluación del potencial de energía renovable y para el desarrollo de políticas de mitigación del cambio climático como REDD+, entre otras. El mapeo de pared a pared de la biomasa sobre el suelo (AGB) ahora es posible con la teledetección satelital (RS). Sin embargo, los métodos de RS requieren datos in situ existentes, actualizados, confiables, representativos y comparables para la calibración y validación. Aquí, presentamos la iniciativa del Sistema de Observación Forestal (FOS), una cooperación internacional para establecer y mantener una base de datos global de biomasa forestal in situ. Las estimaciones de altura de AGB y dosel con sus incertidumbres asociadas se derivan a una escala de 0,25 ha a partir de mediciones de campo realizadas en parcelas de investigación permanentes en los bosques del mundo. Todas las estimaciones de parcelas están geolocalizadas y tienen un tamaño que permite la comparación directa con muchas mediciones de RS. El FOS ofrece el potencial de mejorar la precisión de los productos de biomasa basados en RS al tiempo que desarrolla nuevas sinergias entre las comunidades de investigación de ecosistemas basados en RS y en tierra. Forest biomass is an essential indicator for monitoring the Earth's ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. AGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world's forests. All plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities. الكتلة الحيوية للغابات هي مؤشر أساسي لرصد النظم الإيكولوجية للأرض ومناخها. وهو مدخل حاسم في المحاسبة المتعلقة بغازات الدفيئة، وتقدير خسائر الكربون وتدهور الغابات، وتقييم إمكانات الطاقة المتجددة، ووضع سياسات للتخفيف من آثار تغير المناخ مثل المبادرة المعززة لخفض الانبعاثات الناجمة عن إزالة الغاباتوتدهورها، من بين أمور أخرى. أصبح من الممكن الآن رسم خرائط من الجدار إلى الجدار للكتلة الحيوية فوق الأرض (AGB) باستخدام الاستشعار عن بعد عبر الأقمار الصناعية (RS). ومع ذلك، تتطلب طرق RS بيانات موجودة وحديثة وموثوقة وتمثيلية وقابلة للمقارنة في الموقع للمعايرة والتحقق من الصحة. نقدم هنا مبادرة نظام مراقبة الغابات، وهو تعاون دولي لإنشاء وصيانة قاعدة بيانات عالمية للكتلة الحيوية للغابات في الموقع. يتم اشتقاق تقديرات ارتفاع AGB والمظلة مع أوجه عدم اليقين المرتبطة بها على مقياس 0.25 هكتار من القياسات الميدانية التي تم إجراؤها في قطع البحث الدائمة عبر غابات العالم. جميع تقديرات المخطط محددة جغرافيًا ولها حجم يسمح بالمقارنة المباشرة مع العديد من قياسات RS. يوفر نظام التشغيل الحر إمكانية تحسين دقة منتجات الكتلة الحيوية القائمة على RS مع تطوير أوجه تآزر جديدة بين RS ومجتمعات أبحاث النظام الإيكولوجي الأرضية.

AbstractTropical peatlands are globally significant in the terrestrial carbon cycle as they are comprised of a large forest carbon sink and a large peat carbon store—both of which can potentially be exchanged with the atmosphere on decadal time frames. Greenhouse gas emissions from fire-disturbance and development of tropical peatlands over the last few decades, and the potential for ongoing emissions, highlights the need for policy to slow or halt emissions and to activate mechanisms to sequester carbon through restoration of degraded peatlands. The UN REDD + scheme provides a means for developing countries to receive payments for avoided deforestation and forest degradation, but the steps to achieve REDD+ compliance are rigorous and the details required can be a barrier to activating benefits—especially for peatlands where repeated cycles of fire interrupt forest recovery and create a range of recovery classes. Therefore, to improve estimates of peat fire emissions and of carbon balance of tropical peatlands, the biomass and combustion factor parameters need to be developed and applied according to forest recovery stage. In this study we use published activity data from the extensive 1997 fires in the peatlands of Indonesian Borneo to detail a transparent and accountable way to estimate and report emissions from tropical peatland fires. This example for estimating and reporting emissions is provided to assist REDD+ countries to efficiently develop their capacity for improving emissions estimates from fire-impacted tropical peatlands.

AbstractForest biomass is an essential indicator for monitoring the Earth’s ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (AGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. AGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world’s forests. All plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities.

Understanding the recovery rate of forest carbon stocks and biodiversity after disturbance, including fire, is vital for developing effective climate-change-mitigation policies and actions. In this study, live and dead carbon stocks aboveground, belowground, and in the soil to a 30 cm depth, as well as tree and shrub species diversity, were measured in a tropical lowland dry forest, 23 years after a fire in 1998, for comparison with adjacent unburned reference forests. The results showed that 23 years since the fire was insufficient, in this case, to recover live forest carbon and plant species diversity, to the level of the reference forests. The total carbon stock, in the recovering 23-year-old forest, was 199 Mg C ha−1 or about 90% of the unburned forest (220 Mg C ha−1), mainly due to the contribution of coarse woody debris and an increase in the 5–10 cm soil horizon’s organic carbon, in the burned forest. The carbon held in the live biomass of the recovering forest (79 Mg C ha−1) was just over half the 146 Mg C ha−1 of the reference forest. Based on a biomass mean annual increment of 6.24 ± 1.59 Mg ha−1 yr−1, about 46 ± 17 years would be required for the aboveground live biomass to recover to equivalence with the reference forest. In total, 176 plant species were recorded in the 23-year post-fire forest, compared with 216 in the unburned reference forest. The pioneer species Macaranga gigantea dominated in the 23-year post-fire forest, which was yet to regain the similar stand structural and compositional elements as those found in the adjacent unburned reference forest.

Indonesian mangrove carbon stocks are estimated to be 1,083 ± 378 MgC ha−1. In the past three decades Indonesia has lost 40% of its 2.9 Mha of mangroves; this is estimated to have resulted in annual CO2-equivalent emissions of 0.07–0.21 Pg. Mangroves provide a wide range of ecosystem services, including nutrient cycling, soil formation, wood production, fish spawning grounds, ecotourism and carbon (C) storage1. High rates of tree and plant growth, coupled with anaerobic, water-logged soils that slow decomposition, result in large long-term C storage. Given their global significance as large sinks of C, preventing mangrove loss would be an effective climate change adaptation and mitigation strategy. It has been reported that C stocks in the Indo-Pacific region contain on average 1,023 MgC ha−1 (ref. 2). Here, we estimate that Indonesian mangrove C stocks are 1,083 ± 378 MgC ha−1. Scaled up to the country-level mangrove extent of 2.9 Mha (ref. 3), Indonesia’s mangroves contained on average 3.14 PgC. In three decades Indonesia has lost 40% of its mangroves4, mainly as a result of aquaculture development5. This has resulted in annual emissions of 0.07–0.21 Pg CO2e. Annual mangrove deforestation in Indonesia is only 6% of its total forest loss6; however, if this were halted, total emissions would be reduced by an amount equal to 10–31% of estimated annual emissions from land-use sectors at present. Conservation of carbon-rich mangroves in the Indonesian archipelago should be a high-priority component of strategies to mitigate climate change.

AbstractLess than half of anthropogenic carbon dioxide emissions remain in the atmosphere. While carbon balance models imply large carbon uptake in tropical forests, direct on-the-ground observations are still lacking in Southeast Asia. Here, using long-term plot monitoring records of up to half a century, we find that intact forests in Borneo gained 0.43 Mg C ha−1 per year (95% CI 0.14–0.72, mean period 1988–2010) in above-ground live biomass carbon. These results closely match those from African and Amazonian plot networks, suggesting that the world’s remaining intact tropical forests are now en masse out-of-equilibrium. Although both pan-tropical and long-term, the sink in remaining intact forests appears vulnerable to climate and land use changes. Across Borneo the 1997–1998 El Niño drought temporarily halted the carbon sink by increasing tree mortality, while fragmentation persistently offset the sink and turned many edge-affected forests into a carbon source to the atmosphere.