• Energy Research

Abstract Wood density is a critical control on tree biomass, so poor understanding of its spatial variation can lead to large and systematic errors in forest biomass estimates and carbon maps. The need to understand how and why wood density varies is especially critical in tropical America where forests have exceptional species diversity and spatial turnover in composition. As tree identity and forest composition are challenging to estimate remotely, ground surveys are essential to know the wood density of trees, whether measured directly or inferred from their identity. Here, we assemble an extensive dataset of variation in wood density across the most forested and tree-diverse continent, examine how it relates to spatial and environmental variables, and use these relationships to predict spatial variation in wood density over tropical and sub-tropical South America. Our analysis refines previously identified east-west Amazon gradients in wood density, improves them by revealing fine-scale variation, and extends predictions into Andean, dry, and Atlantic forests. The results halve biomass prediction errors compared to a naïve scenario with no knowledge of spatial variation in wood density. Our findings will help improve remote sensing-based estimates of aboveground biomass carbon stocks across tropical South America.

Abstract This paper presents a case study of charcoal producers supplying a small town in central Mozambique, as a contrast to the predominant focus of previous work on charcoal supply to major urban areas. It gives an in-depth account of the situations in which people produce charcoal, linking this to the role it plays in their livelihoods. Charcoal is made for a diverse set of reasons ranging from women wishing for financial autonomy from their husbands, through to gaining supplementary income from field opening. Those making charcoal have a wide range of livelihood strategies and produce in a wide range of situations. The findings counter the idea that charcoal production is a livelihood of last resort. Furthermore, the current de-facto licencing regime facilitates this diversity, but stands in contrast to the law. Enforcing the full requirements of the law would possibly reduce the flexible opportunities for income that charcoal provides for many households within the study area.

Agriculture needs to reduce inputs of inorganic fertilizers and close the loop on nutrients that can otherwise become environmental pollutants. This can be achieved by promoting recycling of nutrients within the agricultural landscape. We investigated the extent to which plants found in riparian buffer zones have the potential to provide nutrients to crops as a green manure, through plant growth and decomposition studies. Under controlled conditions, species typical of Scottish riparian buffer strips were tested for their ability to accumulate biomass and nutrients in tissue under N‐ and P‐replete conditions and whether this ability enhanced the utility of the resulting green manure in promoting crop growth. In this proof‐of‐concept study, we found that green manure derived from riparian buffer strips did not effectively replace inorganic fertilizer and only had a significant positive effect on growth, yield, and nutrient accumulation in barley (Hordeum vulgare L.) when it was integrated with the addition of inorganic fertilizers. The individual species tested varied in the amount of P they accumulated in their tissue (1.38–52.73 mg P plant−1), but individual species did not differ in their ability to promote yield when used as a green manure. Our results indicate that selecting certain species in the buffer strip on the basis of their nutrient accumulating abilities is not an effective way to increase the utility of buffer strip green manure as a nutrient source for crops.Core Ideas We need to close the loop on nutrients that become environmental pollutants. Green manure from riparian buffer strips cannot replace chemical fertilizers. Buffer strip green manure integrated with fertilizer promotes plant growth. Common riparian buffer species have variation in nutrient accumulation. Selection of P‐ and N‐accumulating plants does not provide a superior green manure.

International climate negotiations have stressed the importance of considering emissions from forest degradation under the planned REDD+ (Reducing Emissions from Deforestation and forest Degradation + enhancing forest carbon stocks) mechanism. However, most research, pilot-REDD+ projects and carbon certification agencies have focused on deforestation and there appears to be a gap in knowledge on complex mosaic landscapes containing degraded forests, smallholder agriculture, agroforestry and plantations. In this paper we therefore review current research on how avoided forest degradation may affect emissions of greenhouse gases (GHG) and expected co-benefits in terms of biodiversity and livelihoods. There are still high uncertainties in measuring and monitoring emissions of carbon and other GHG from mosaic landscapes with forest degradation since most research has focused on binary analyses of forest vs. deforested land. Studies on the impacts of forest degradation on biodiversity contain mixed results and there is little empirical evidence on the influence of REDD+ on local livelihoods and tenure security, partly due to the lack of actual payment schemes. Governance structures are also more complex in landscapes with degraded forests as there are often multiple owners and types of rights to land and trees. Recent technological advances in remote sensing have improved estimation of carbon stock changes but establishment of historic reference levels is still challenged by the availability of sensor systems and ground measurements during the reference period. The inclusion of forest degradation in REDD+ calls for a range of new research efforts to enhance our knowledge of how to assess the impacts of avoided forest degradation. A first step will be to ensure that complex mosaic landscapes can be recognised under REDD+ on their own merits.

Dans les centres urbains du Mozambique, le charbon de bois est la principale source d'énergie pour la cuisson. La demande croissante entraîne des taux élevés d'extraction du bois sur des zones croissantes de forêts de miombo et de mopane. La production de charbon de bois peut entraîner des changements dans la fourniture de services écosystémiques et la dégradation des forêts tout en contribuant de manière significative au revenu rural et, éventuellement, à la réduction de la pauvreté. En tant que tel, la compréhension de la production et du commerce du charbon de bois a des implications importantes pour les zones rurales et pour le développement durable des ressources forestières. Ici, nous étudions la production et le commerce du charbon de bois grâce à des recherches empiriques menées dans la province de Gaza, la principale source de charbon de bois région de Maputo, Mozambique.Nous analysons la structure actuelle des principales chaînes d'approvisionnement en charbon de bois de la province de Gaza à Maputo et la répartition des bénéfices le long de celles-ci.Sept villages du district de Mabalane, à Gaza, à différents stades d'engagement avec l'industrie du charbon de bois, ont été sélectionnés pour enquête.Nous avons mené des enquêtes auprès des ménages et des entretiens semi-structurés avec des informateurs clés (chefs de village, producteurs de charbon de bois, titulaires de licence, grossistes, transporteurs et techniciens forestiers), de mai à octobre 2014.Nos résultats mettent en évidence deux principales chaînes d'approvisionnement en charbon de bois comprenant quatre principaux groupes d'acteurs a) Petites entreprises locales les opérateurs produisant du charbon de bois à petite échelle avec la main-d' œuvre des ménages, qui vendent aux grossistes b) Les opérateurs à grande échelle produisant et commercialisant de grands volumes de charbon de bois à l'aide de main-d' œuvre migrante, qui vendent leur propre production aux grossistes.Bien que la production de charbon de bois constitue une source de revenus importante pour les ménages ruraux de Mabalane, dans le cadre de la chaîne d'approvisionnement a) plus de 90% des avantages monétaires n'atteignent pas les communautés locales et restent avec des agents externes.Les deux principaux facteurs entravant la génération de revenus plus importants au niveau communautaire sont : 1) les charges bureaucratiques liées à l'obtention des droits de commercialisation du charbon de bois sous forme de licences ; et 2) les faibles capacités institutionnelles pour la gouvernance des ressources forestières.Nous concluons que l'accès aux marchés et le contrôle des forêts sont essentiels si les communautés locales veulent générer de plus grands avantages de la production de charbon de bois tout en visant une production durable de charbon de bois.Les institutions locales fortes pour l'obtention des droits de commercialisation et la gestion des ressources forestières doivent être développées, tandis que la restructuration du système d'octroi de licences en faveur des petits producteurs et un contrôle plus rigoureux de la réglementation pourraient soutenir ce processus. En los centros urbanos de Mozambique, el carbón vegetal es la principal fuente de energía para cocinar. La creciente demanda impulsa altas tasas de extracción de madera en áreas crecientes de bosques de miombo y mopane. La producción de carbón vegetal puede conducir a cambios en la provisión de servicios ecosistémicos y la degradación de los bosques, al tiempo que contribuye significativamente a los ingresos rurales y, posiblemente, a la mitigación de la pobreza. Por lo tanto, comprender la producción y el comercio de carbón vegetal tiene implicaciones importantes para las áreas rurales y para el desarrollo sostenible de los recursos forestales. Aquí, investigamos la producción y el comercio de carbón vegetal a través de investigaciones empíricas realizadas en la provincia de Gaza, el principal suministro de carbón vegetal área de Maputo, Mozambique. Analizamos la estructura actual de las principales cadenas de suministro de carbón desde la provincia de Gaza hasta Maputo y la distribución de beneficios a lo largo de ellas. Se seleccionaron siete aldeas en el distrito de Mabalane, Gaza, en diferentes etapas de compromiso con la industria del carbón. Realizamos encuestas de hogares y entrevistas semiestructuradas con informantes clave (líderes de aldeas, productores de carbón, titulares de licencias, mayoristas, transportistas y técnicos forestales), de mayo a octubre de 2014. Nuestros resultados destacan dos cadenas principales de suministro de carbón que comprenden cuatro grupos de actores principales a) Pequeña escala local operadores que producen carbón vegetal a pequeña escala con mano de obra doméstica, que venden a mayoristas b) Operadores a gran escala que producen y comercializan grandes volúmenes de carbón vegetal utilizando mano de obra migrante, que venden su propia producción a mayoristas. Si bien la producción de carbón vegetal constituye una importante fuente de ingresos para los hogares rurales en Mabalane, en la cadena de suministro a) más del 90% de los beneficios monetarios no llegan a las comunidades locales y permanecen con agentes externos. Dos de los principales factores que impiden la generación de mayores ingresos a nivel comunitario son: 1) las cargas burocráticas para obtener derechos de comercialización de carbón vegetal en forma de licencias; y 2) las débiles capacidades institucionales para la gobernanza de los recursos forestales. Concluimos que el acceso a los mercados y el control sobre los bosques es clave para que las comunidades locales generen mayores beneficios de la producción de carbón vegetal mientras apuntan a la producción sostenible de carbón vegetal. Deben desarrollarse instituciones locales sólidas para obtener derechos de comercialización y gestionar los recursos forestales, mientras que la reestructuración del sistema de licencias a favor de los pequeños productores y un control más riguroso de las regulaciones podrían apoyar este proceso. In urban centres of Mozambique, charcoal is the major energy source for cooking.Growing demand drives high wood extraction rates over increasing areas of miombo and mopane woodlands.Charcoal production can lead to changes in ecosystem service provision and woodland degradation while also significantly contributing to rural income and, possibly, poverty alleviation.As such, understanding charcoal production and trade has important implications for rural areas and for the sustainable development of woodland resources.Here, we investigate charcoal production and trade through empirical research conducted in Gaza Province, the main charcoal supply area for Maputo, Mozambique.We analyse the present structure of the main charcoal supply chains from Gaza province to Maputo and the profit distribution along them.Seven villages in the Mabalane district, Gaza, at different stages of engagement with the charcoal industry, were selected for investigation.We conducted household surveys and semi-structured interviews with key informants (village leaders, charcoal producers, licence holders, wholesalers, transporters and forest technicians), from May to October 2014.Our results highlight two main charcoal supply chains comprising four main actor groups a) Local small-scale operators producing charcoal on a small-scale with household labour, who sell to wholesalers b) Large-scale operators producing and commercialising large volumes of charcoal using migrant labour, who sell their own production to wholesalers.While charcoal production constitutes an important income source for rural households in Mabalane, under supply chain a) more than 90% of the monetary benefits do not reach local communities and remain with external agents.Two of the main factors impeding the generation of greater revenues at community level are: 1) bureaucratic burdens in obtaining charcoal commercialisation rights in the form of licences; and 2) weak institutional capacities for woodland resource governance.We conclude that access to markets and control over woodlands is key if local communities are to generate greater benefits from charcoal production while aiming at sustainable charcoal production.Strong local institutions for obtaining commercialisation rights and managing woodland resources have to be developed, while the restructuring of the licencing system in favour of small-scale producers and more rigorous control of the regulations could support this process. في المراكز الحضرية في موزمبيق، يعد الفحم مصدر الطاقة الرئيسي للطهي. يؤدي الطلب المتزايد إلى ارتفاع معدلات استخراج الأخشاب على مناطق متزايدة من غابات الميومبو والموبان. يمكن أن يؤدي إنتاج الفحم إلى تغييرات في توفير خدمات النظام الإيكولوجي وتدهور الغابات مع المساهمة أيضًا بشكل كبير في الدخل الريفي، وربما التخفيف من حدة الفقر. على هذا النحو، فإن فهم إنتاج الفحم وتجارته له آثار مهمة على المناطق الريفية وعلى التنمية المستدامة لموارد الغابات. هنا، نقوم بالتحقيق في إنتاج الفحم وتجارته من خلال البحوث التجريبية التي أجريت في محافظة غزة، وهي مصدر الفحم الرئيسي منطقة مابوتو، موزمبيق. قمنا بتحليل الهيكل الحالي لسلاسل توريد الفحم الرئيسية من محافظة غزة إلى مابوتو وتوزيع الأرباح على طولها. تم اختيار سبع قرى في منطقة مابالاني، غزة، في مراحل مختلفة من المشاركة مع صناعة الفحم، للتحقيق فيها. أجرينا دراسات استقصائية للأسر المعيشية ومقابلات شبه منظمة مع المخبرين الرئيسيين (قادة القرى ومنتجي الفحم وأصحاب التراخيص وتجار الجملة والناقلين وفنيي الغابات)، من مايو إلى أكتوبر 2014. تسلط نتائجنا الضوء على سلسلتين رئيسيتين لتوريد الفحم تضم أربع مجموعات فاعلة رئيسية أ) على نطاق صغير محلي المشغلون الذين ينتجون الفحم على نطاق صغير مع العمالة المنزلية، الذين يبيعون لتجار الجملة ب) المشغلون على نطاق واسع ينتجون ويسوقون كميات كبيرة من الفحم باستخدام العمالة المهاجرة، الذين يبيعون إنتاجهم الخاص لتجار الجملة. في حين أن إنتاج الفحم يشكل مصدر دخل مهم للأسر الريفية في مابالاني، في إطار سلسلة التوريد أ) أكثر من 90 ٪ من الفوائد النقدية لا تصل إلى المجتمعات المحلية وتبقى مع وكلاء خارجيين. اثنان من العوامل الرئيسية التي تعوق توليد إيرادات أكبر على مستوى المجتمع هي: 1) الأعباء البيروقراطية في الحصول على حقوق تسويق الفحم في شكل تراخيص ؛ و 2) ضعف القدرات المؤسسية لإدارة موارد الغابات. نستنتج أن الوصول إلى الأسواق والسيطرة على الغابات أمر أساسي إذا كانت المجتمعات المحلية ستولد فوائد أكبر من إنتاج الفحم مع استهداف إنتاج الفحم المستدام. يجب تطوير مؤسسات محلية قوية للحصول على حقوق التسويق وإدارة موارد الغابات، في حين أن إعادة هيكلة نظام الترخيص لصالح صغار المنتجين والسيطرة الأكثر صرامة على هذه العملية يمكن أن تدعم.

AbstractData capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research—from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non‐forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC‐BY 4.0 licence and can be access from: https://doi.org/10.5281/zenodo.6637599. To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology—from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle.