Research Design, Soil and Biodiversity Baseline for Long-term Farming Systems Comparison of Full Sun and Shaded Agroforestry Cocoa Production under Conventional and Organic Management in Alto Beni, Bolivia

Cocoa, mainly produced by 5 to 6 millions of smallholder farmers, is considered as one of the most sustainable production system in the humid tropics. Little is known about the sustainability of different cocoa production systems. A long-term experiment is set up in Alto Beni at 400m above sea level with a humid winter dry climate, 1’540 mm annual rainfall. The trial assesses the sustainability of five cocoa (Theobroma cacao) production systems with the parameters of yield and yield stability, input-output efficiency of nutrients and energy, soil fertility, biodiversity, economic result, climate change mitigation and adaptation. The two-factorial experiment is arranged in an completely randomised block design; the five cocoa treatments, based on local and international practices, are four times repeated. The production systems are differentiated by the diversity of shade canopy and by crops, from mono culture full sun cocoa to a agroforestry cocoa with leguminous species (Inga edulis, Erythrina poeppigiana) shade canopy, including fruits (e.g. Euterpe precatoria, Theobroma grandiflorum) and timber (e.g. Centrolobium ochroxylum, Swietenia macrophylla) species, and a higher diversified agroforestry system based on the natural successions of species. The management of the cocoa is conventional and organic. The five treatments are: mono culture full sun cocoa conventional, mono culture full sun organic, agroforestry conventional, agroforestry organic and successional agroforestry organic. Fallow plots and nearby forests plots are monitored for soil fertility and biodiversity. Field clearing started in 2007 followed by maize (Zea mays) crop and end of 2008 the cocoa plots (48m×48 m) were established. The results of the baseline studies concerning soil fertility show good nutrient level for cocoa production; the variance of soil parameters is documented in a soil map. According the FAO soil classification (2006) the soils are Lixisole and Luvisole with high base saturation

Challenges and approaches in data management of LTE trials in tropical field sites: Experiences from two trials in India and Bolivia

Quality data is the key commodity of research projects. But with the size of a research project, number of parties involved and range of data collected, the complexity of data management increases significantly. In long-term experiments (LTE), continuity and comparability of collected data throughout the study duration is important but being challenged by personnel changes and development in infrastructure and technology, as well as changes to the trial itself. Managing a longterm trial remotely at field sites in the tropics adds another layer of challenges, including timely transfer of new data, time consuming pre-processing and validation of data between field and scientific staff, data literacy of local field staff and language barriers due to varying levels of English and local languages within the project team. We share our challenges in data management and the strategies and tools used in the context of two LTE trials with field sites in India and Bolivia, managed by local partner organizations and coordinated by the Research Institute of Organic Agriculture in Switzerland, highlighting the technical infrastructure in use, definition of responsibilities and workflows. Our main considerations are a) finding a balance between data security, easy and timely sharing of data in both directions and minimising number of different data repositories and file versions, b) the use of simple, well-known tools that are flexible enough to consider (evolving) needs of different involved parties including field staff, and c) the importance of quick data availability for analysis to serve as a basis for decision making in trial management

Productivity and income in 5 different cocoa production systems

Cocoa agroforestry systems, combining cocoa with timber and fruit trees, are mainly promoted for their environmental benefits. Knowledge gaps exist about the economic performance of such systems. Here we present the productivity and income of 5 cocoa production systems from planting to entering the mature stage 11 years)

Organic management enhances soil quality and drives microbial community diversity in cocoa production systems

Maintaining soil quality for agricultural production is a critical challenge, especially in the tropics. Due to the focus on environmental performance and the provision of soil ecosystem services, organic farming and agroforestry systems are proposed as alternative options to conventional monoculture farming. Soil processes underlying ecosystem services are strongly mediated by microbes; thus, increased understanding of the soil microbiome is crucial for the development of sustainable agricultural practices. Therefore, we measured and related soil quality indicators to bacterial and fungal community structures in five cocoa production systems, managed either organically or conventionally for 12 years, with varying crop diversity, from monoculture to agroforestry. In addition, a successional agroforestry system was included, which uses exclusively on-site pruning residues as soil inputs. Organic management increased soil organic carbon, nitrogen and labile carbon contents compared to conventional. Soil basal respiration and nitrogen mineralisation rates were highest in the successional agroforestry system. Across the field sites, fungal richness exceeded bacterial richness and fungal community composition was distinct between organic and conventional management, as well as between agroforestry and monoculture. Bacterial community composition differed mainly between organic and conventional management. Indicator species associated with organic management were taxonomically more diverse compared to taxa associated with conventionally managed systems. In conclusion, our results highlight the importance of organic management for maintaining soil quality in agroforestry systems for cocoa production

Above- and belowground biomass and nutrient stocks in monoculture and agroforestry cacao production systems in the Alto Beni, Bolivia

Prácticamente no queda ningún lugar en el planeta que pueda considerarse como naturaleza intacta. Los humanos penetran en todas las áreas de esta tierra, ya sea a través de las emisiones de gases de efecto invernadero o de otros tipos de contaminación atmosférica y ambiental. La deforestación y la conversión del suelo a la agricultura son procesos que acompañan a la expansión de los humanos en esta tierra, y que dan forma a los paisajes. En este contexto, los bosques tropicales están hoy en día en el punto de mira de la deforestación y el cambio de uso del suelo. Para mantener o restaurar las funciones del ecosistema y la biodiversidad de los bosques tropicales, se necesitan usos alternativos del suelo agrícola. Para examinar sistemas de producción alternativos, el Instituto de Investigación en Agricultura Orgánica (FiBL) puso en marcha el proyecto de investigación "Comparación de sistemas de cultivos en los trópicos" (https://systems-comparison.fibl.org/). En Alto Beni (Bolivia) se están probando cinco sistemas diferentes de producción de cacao en un ensayo a largo plazo con respecto a sus impactos económicos, ecológicos y sociales. Los sistemas de cultivo van desde los monocultivos hasta los sistemas agroforestales simples, cada uno de ellos bajo gestión convencional y orgánica, pasando por los sistemas agroforestales multistrata altamente complejos. Las parcelas se establecieron en 2008, en un diseño de bloques completamente randomizados, con cuatro réplicas. El objetivo general de esta tesis es comparar, dentro del experimento a largo plazo en Bolivia, los diferentes sistemas de cultivo de cacao en términos de su capacidad para acumular y convertir el carbono, y sacar conclusiones sobre la disponibilidad de nutrientes a través de la actividad microbiana. Se planteó la hipótesis de que (1) los AFS almacenan más biomasa por encima y por debajo del suelo, en forma de carbono, a lo largo del tiempo, y que (2) tanto el manejo orgánico como los AFS dan lugar a una mayor actividad biológica. Para verificar esto, (1) se estudiaron los diferentes reservorios de biomasa sobre el suelo, (2) se midió la biomasa obtenida de la poda, (3) se registró la caída anual de hojas, (4) se analizó la descomposición de la hojarasca en un año, y (5) se estimó el crecimiento de las raíces.   El trabajo realizado mostró que la biomasa total sobre el suelo es mayor en los AFS que en los monocultivos. Sin embargo, en los monocultivos, la biomasa de los árboles de cacao es mayor que en los otros sistemas de cultivo. La biomasa total sobre el suelo en AFS es sólo un tercio de la biomasa acumulada en los árboles de los bosques circundantes. En los AFS bien manejados, la biomasa producida por la poda puede ser el doble de la caída natural de las hojas, y es por lo tanto una importante fuente de carbono y nitrógeno. La vida media de la descomposición de la hojarasca en los distintos sistemas no difirió, a pesar de los diferentes microclimas y de la mayor actividad microbiana en las parcelas manejadas orgánicamente. Las hojas ricas en nitrógeno de las leguminosas se descompusieron más rápidamente que las hojas de cacao, ricas en lignina. La calidad del suelo mejoro 6 años después de la instalación, en las parcelas manejadas orgánicamente en comparación con las parcelas convencionales, como lo demuestran los mayores niveles de carbono y nitrógeno, así como una mayor actividad microbiana. El crecimiento de las raíces finas también es mayor en las parcelas de AFS y de gestión biológica que en los monocultivos. Los diferentes estudios muestran que los AFS tienen una pronunciada ventaja sobre los monocultivos en términos de acumulación de biomasa, aunque no alcancen el nivel de los bosques primarios o secundarios. Los trabajos muestran que existe una fuerte vinculación de los diferentes depósitos de carbono en los AFS. La mayor biomasa sobre el suelo y las leguminosas de rápido crecimiento permiten una poda regular, que estimula el ciclo del carbono y del nitrógeno. La hojarasca acumulada es descompuesta por los microorganismos, lo que permite mejorar las condiciones del suelo y la disponibilidad de nutrientes. Por lo tanto, del presente trabajo se puede concluir que el AFS no puede impedir per se la deforestación de los bosques tropicales para la obtención de tierras agrícolas. Sin embargo, los AFS, a diferencia de los monocultivos, tienen un mejor balance ecológico, con más biomasa y mejores suelos. Por lo tanto, los AFS, más estables y sostenibles, son preferibles, desde una perspectiva ecológica, a los monocultivos diseñados para obtener beneficios a corto plazo.Auf der Erde gibt es kaum noch einen Ort, der als Unberührte Natur gelten kann. Der Mensch dringt in alle Bereich dieser Erde vor, und sei es durch Treibhausgasemissionen oder andere Arten der Luft- und Umweltverschmutzung. Waldrodungen und die Nutzbarmachung der Flächen für die Landwirtschaft sind Prozesse, die die Ausbreitung des Menschen auf dieser Erde begleiten, und die die Landschaften gestalten. Die tropischen Wälder stehen dabei heutzutage im Fokus der Waldrodung und des Landnutzungswandels. Um die ökosystemaren Funktionen und die Biodiversität der tropischen Wälder zu erhalten oder wiederherzustellen, bedarf es alternativer Landwirtschaftlichernutzungsformen. Um alternative Produktionssysteme zu testen, wurde vom Forschungsinstituts für Ökologischen Landbau (FiBL) das Forschungsprojekte “Vergleich von Anbausystemen in den Tropen” ins leben gerufen (https://systems-comparison.fibl.org/). Im Alto Beni (Bolivien) werden in einem Langzeitversuch fünf verschiedene Kakaoanbausysteme hinsichtlich ihrer ökonomischen, ökologischen und sozialen Auswirkungen getestet. Die Anbausysteme reichen von Monokulturen über einfache Agroforstsystemen, jeweils in konventioneller und ökologischer Bewirtschaftung, hin zu hoch komplexen sukzessionalen, multistrato Agroforstsystemen. Die Flächen wurden 2008, in einem vollständig randomisierten Blockdesign, mit vierfacher Wiederholung eingerichtet. Das generelle Ziel dieser Doktorarbeit ist im Rahmen des Langzeitversuches in Bolivien die verschiedenen Kakaoanbausysteme zu vergleichen, hinsichtlich Ihrer Kapazität Kohlenstoff zu speichern und umzusetzen, sowie Rückschlüsse zu ziehen auf die Verfügbarkeit von Nährstoffen durch die mikrobielle Aktivität. Es wurden die Hypothesen aufgestellt, dass (1) AFS mehr Ober- und Unterirdischebiomasse, in Form von Kohlenstoff, über die Zeit speichern, und dass (2) sowohl ein biologisches Management als auch AFS dazuführen, dass eine höhere biologische Aktivität vorherrscht. Um dies zu überprüfen, wurden (1) die verschiedenen oberirdischen Biomassepools untersucht, (2) die anfallende Biomasse durch den Baumschnitt erfasst, (3) der jährliche Blattfall aufgenommen, (4) die Zersetzung der Blattstreu binnen eines jahres analysiert, und (5) das Wurzelwachstum abgeschätzt. Die durchgeführten Arbeiten haben gezeigt, dass die gesamte oberirdische Biomasse in den AFS größer ist als in den Monokulturen. Jedoch ist in den Monokulturen die Biomasse der Kakaobäume größe als in den anderen Anbausystemen. Die gesamte oberirdische Biomasse in den AFS beträgt nur etwa ein Drittel der Biomasse, die in den Bäumen der umliegenden Wälder gespeichert ist. In gemanagten AFS kann die Biomasse, die durch den Baumschnitt anfällt, doppelt so hoch sein wie der natürliche Laubfall, und ist somit eine wichtige Kohlenstoff und Stickstoff Quelle. Die Halbwertszeit der Streuzersetzung in den verschiedenen Systemen unterschied sich nicht, trotz unterschiedlichem Mikroklima und höherer Mikrobielleraktivität in den organisch gemanagten Flächen. Stickstoffreiche Blätter von Leguminosen wurden schneller zersetzt als die ligninhaltigen Kakaoblätter. Die Bodenqualität ist 6 Jahren nach der Installation, in den biologisch gemanagten Flächen verbessert im Vergleich zu den konventionellen Flächen, was sich sowohl durch höhere Kohlenstoff und Stickstoff Werte bemerkbar macht, als auch in einer höheren mikrobiellen Aktivität. Auch das Feinwurzelwachstum ist in AFS und biologisch gemanagten Flächen größer, als in den Monokulturen. Die unterschiedlichen Untersuchungen zeigen, dass AFS hinsichtlich der Biomassenakkumulation einen ausgeprägten Vorteil haben gegenüber Monokulturen, auch wenn sie nicht das Niveau der Primär- oder Sekundärwälder erreichen. Die Arbeit zeigt, dass es in den AFS eine starke Verknüpfung der verschiedenen Kohlenstoffpools gibt. Mehr oberirdische Biomasse und schnell-wachsende Leguminosen ermöglichen einen regelmäßigen Baumschnitt, der den Kohlenstoff- und Stickstoffkreislauf anregt. Die anfallende Streu wird von Mikroorganismen zersetzt und führt zu besseren Bodenverhältnissen und der Verfügbarkeit von Nährstoffen. Aus der vorliegenden Arbeit lässt sich daher ableiten, dass AFS nicht per se die Abrodung der Regenwälder für landwirtschaftliche Flächen verhindern können. AFS im Gegensatz zu Monokulturen jedoch eine bessere ökologische Bilanz aufweisen, mit mehr Biomasse und besseren Böden. Die stabileren und nachhaltigeren AFS sind daher aus ökologischer Perspektive den auf kurzfristigen Gewinn ausgelegten Monokulturen vorzuziehen.There is hardly any place left on earth that can be considered untouched nature. Humans penetrate into all areas of this earth, and may it be through greenhouse gas emissions or other types of air and environmental pollution. Deforestation and the conversion of land to agriculture are processes that accompany the spread of humans on this earth, and which shape the landscapes. In this context, tropical forests are nowadays in the focus of forest clearing and land use change. To maintain or restore the ecosystem functions and biodiversity of tropical forests, alternative agricultural land uses are needed. In order to test alternative production systems, the Research Institute of Organic Agriculture (FiBL) launched the research project "Comparison of cropping systems in the tropics" (https://systems-comparison.fibl.org/). In Alto Beni (Bolivia), five different cacao production systems are being tested in a long-term trial with regard to their economic, ecological and social impacts. The farming systems range from monocultures to simple agroforestry systems, each under conventional and organic management, to highly complex successional, multistrata agroforestry systems. The plots were established in 2008, in a completely randomized block design, with four replications. The general objective of this dissertation is to compare, within the long-term experiment in Bolivia, the different cacao cropping systems in terms of their capacity to store and convert carbon, and to draw conclusions on the availability of nutrients through microbial activity. It was hypothesized that (1) AFS store more above and below ground biomass, in the form of carbon, over time, and that (2) both biological management and AFS result in higher biological activity. To verify this, (1) the different aboveground biomass pools were studied, (2) the biomass obtained from pruning was measured, (3) the annual leaf fall was recorded, (4) the decomposition of leaf litter within one year was analyzed, and (5) the root growth was estimated. The work performed showed that total aboveground biomass is greater in AFS than in monocultures. However, in the monocultures, the biomass of cacao trees is larger than in the other cropping systems. The total aboveground biomass in AFS is only about one-third of the biomass stored in trees in the surrounding forests. In managed AFS, the biomass produced by pruning can be twice that of natural leaf fall, and is thus an important source of carbon and nitrogen. The half-life of litter decomposition in the different systems did not differ, despite different microclimates and higher microbial activity in the organically managed plots. Nitrogen-rich leaves of legumes were decomposed faster than lignin-rich cacao leaves. Soil quality is improved 6 years after installation, in the organically managed plots compared to the conventional plots, as evidenced by higher carbon and nitrogen levels, as well as higher microbial activity. Fine root growth is also greater in AFS and biologically managed plots than in the monocultures. The different studies show that AFS have a pronounced advantage over monocultures in terms of biomass accumulation, even if they do not reach the level of primary or secondary forests. The work shows that there is a strong linkage of the different carbon pools in AFS. More aboveground biomass and fast-growing legumes allow regular pruning, which stimulates carbon and nitrogen cycling. Accumulated litter is decomposed by microorganisms, leading to better soil conditions and nutrient availability. Therefore, it can be concluded from the present work that AFS cannot per se prevent the clearing of rainforests for agricultural land. However, AFS, unlike monocultures, have a better ecological balance, with more biomass and better soils. The more stable and sustainable AFS are therefore preferable from an ecological perspective to monocultures which are designed for short-term profit.2022-03-1

Economic Performance of Five Different Cacao Production Systems

Agroforestry systems for cocoa production are commonly promoted for biodiversity conservation, climate change mitigation and adaptation as well as for food security and risk mitigation. Generally, these systems include timber, legume or fruit trees, and sometimes additional crops. Knowledge gaps exist about the economic performance of cocoa based agroforestry systems, including the by-crops. Here we present the economic performance of 5 cocoa production systems from planting to entering the mature stage (11 years). In a long-term trial in Bolivia, a gradient of complexity from monocultures, agroforestry systems to successional agroforestry systems (SAFS) is studied. Additionally, for monocultures and agroforestry, conventional and organic management are compared, while SAFS are managed organically. Income was calculated taking into account yields of cocoa, fruit trees and by-crops with farm gate prices. Only for cocoa organic premium prices were reached and taken into account. Labour time was registered for management, input preparation and post-harvest. Cocoa yields were lower in the agroforestry systems compared with monocultures, and lowest in SAFS. For monocultures, they were higher under conventional management, while in agroforestry systems management had no influence. Total system yields in agroforestry systems (dry matter) were 3–4 times higher than in monocultures. This was mainly due to banana production in agroforestry systems and from a diversity of by-crops in SAFS. Income over all years was comparable among all systems. In agroforestry systems, cocoa was responsible for more than 50 % of the income, while in SAFS the share of cocoa was smaller, as some crops like pineapples or peach palm had good markets in the region. The income generated per workday invested during the whole period did not differ between the systems. Income analysis shows the importance of cocoa as a cash crop, but also the potential of by-crops depending on the development of their markets. On the other hand, agroforestry systems contribute to food security and mitigate risks of price or yield fluctuations in the cash crop. In conclusion, the data show that with different strategies and plantation design, the same level of income and income per work day invested can be reached. More information on the trial layout can be found here: https://systems-comparison.fibl.or

Below- and aboveground production in cocoa monocultures and agroforestry systems

Farmers expect yield reduction of cash crops like cocoa when growing in agroforestry systems compared to monocultures, due to competition for resources, e.g. nutrients and water. However, complementarities between species in the use of resources may improve resource use efficiency and result in higher system performance. Cocoa trees have a shallow rooting system while the rooting characteristics of the associated trees are mainly unknown. This work investigates fine root distribution and production in five cocoa production systems: two monocultures and two agroforestry systems under conventional and organic farming, and a successional agroforestry system. In the organic systems a perennial leguminous cover crop was planted and compost was added, while herbicides and chemical fertilizers were applied in the conventional ones. We measured cocoa fine root parameters in the top 10 cm of soil and annual total fine root production at 0–25 and 25–50 cm depth. We related the root data with both the aboveground performance (tree and herbaceous biomass), and the cocoa and system yields. Cocoa fine roots were homogenously distributed over the plot area. Around 80% of the total fine roots were located in the upper 25 cm of soil. The total fine root production was 4-times higher in the agroforestry systems and the organic monoculture than in the conventional monoculture. The roots of the associated tree species were located in the same soil space as the cocoa roots and, in principle, competed for the same soil resources. The cocoa yield was lower in the agroforestry systems, but the additional crops generated a higher system yield and aboveground biomass than the conventional cocoa monocultures, implying effective resource exploitation. The leguminous cover crop in the organic monoculture competed with the cocoa trees for nutrients, which may explain the lower cocoa yield in this system in contrast with the conventional monoculture

Different agroforestry designs for diversified organic cocoa production – cocoa and by-crop yield development in 11 years of a long-term trial

Agroforestry systems for cocoa production are commonly promoted for biodiversity conservation, climate change mitigation and adaptation as well as for food security and risk mitigation. Generally, these systems include timber, legume or fruit trees. Sucessional or dynamic agroforestry systems represent a special type of design and management approach, using high densities and diversity of trees and crops occupying different strata and with varying life cycles. Here we present results on absolute and potential yields of 3 organic cocoa production systems entering the mature stage from a long-term trial in Bolivia: A complex successional dynamic agroforestry system (SAFS), a simpler but diversified agroforestry system (AF ORG) and a cocoa monoculture (MONO ORG). Cocoa yields were highest in MONO ORG, followed by the AF ORG, and lowest in SAFS. Total system yields in both types of agroforestry systems (dry matter) were 3.5 to 4 times higher than in monocultures over the 11 years. This was mainly due to banana production in AF ORG and from a multitude of by-crops in SAFS. In mature SAFS peach palm was the by-crop with the highest dry matter production. The results demonstrate how different crops can be associated with cocoa while still reaching elevated cocoa yields. The potential of agroforestry systems to sustainably intensify production on one surface is high and could still be optimised with the use of improved and locally selected varieties of cocoa and fruit trees. Different designs of agroforestry systems can contribute to diversification of diets and incomes of producing families and regions

Cocoa and by-crop yields in three organic production systems entering mature stage

Agroforestry systems for cocoa production are commonly promoted for biodiversity conservation, climate change mitigation and adaptation as well as for food security and risk mitigation. Generally, these systems include timber, legume or fruit trees. Sucessional or dynamic agroforestry systems represent a special type of design and management approach, using high densities and diversity of trees and crops occupying different strata and with varying life cycles. Here we present yields of three organic cocoa production systems entering the mature stage from a long-term trial in Bolivia: A complex successional dynamic agroforestry system (SAFS), a simpler but diversified agroforestry system (AF ORG) and a cocoa monoculture (MONO ORG). Average cocoa yields in the mature phase (9-11 years) were highest in MONO ORG (1520 kg/ha), followed by the AF ORG (910 kg/ha), and lowest in SAFS (790 kg/ha) (yields considering the 8 best yielding clones out of 12. Total system yields in both types of agroforestry systems (dry matter) were 3.5 to 4 times higher than in monocultures over the 11 years. This was mainly due to banana production in AF ORG and from a multitude of by-crops in SAFS. While in young SAFS(until 8 years) crops like cassava, and pineapple were contributing to total yields, peach palm was the most relevant by-crop in the mature phase with around 4 t/ha fresh yields. Additional interesting crops were ginger and curcuma, that growing under the cocoa in SAFS yielded around 1 kg of fresh tubers per m2. The results demonstrate how different crops can be associated with cocoa while still reaching elevated cocoa yields. The potential of agroforestry systems to sustainably intensify production on one surface is high and could still be optimised with the use of improved and locally selected varieties of cocoa and by-crops. Different designs of agroforestry systems can contribute to diversification of diets and incomes of producing families and regions

Forest structural parameters and aboveground biomass in old-growth and secondary forests along an elevational gradient in Mexico

Background: Tropical montane forests are important reservoirs of carbon and biodiversity but are threatened by deforestation and climate change. It is important to understand how forest structure and aboveground biomass change along gradients of elevation and succession. Questions: What are the interactive effect of elevation and two stages of succession on forest structure parameters? Studied species: Tree communities. Study site and dates: Cofre de Perote, Veracruz, Mexico. August to December 2015. Methods: We studied four sites along an elevational gradient (500, 1,500, 2,500, and 3,500 m). At each elevation and each forest type, we established five 20 × 20 m plots (n = 40 plots). Within each plot, we measured stem density, mean diameter at breast height (dbh), and tree height and derived basal area and aboveground biomass (AGB). Results: AGB peaked at 2,500 m and was significantly related to elevation and succession, with higher values in old-growth forests than in secondary forests at higher altitudes. Lower values of mean dbh and basal area were found at higher elevations. At the lowest elevation, both successional stages had the same values of stem density and AGB. At both lower elevations, secondary forests had higher values of dbh and basal area. There were high biomass stocks in the old-growth forest at 2,500 and 3,500 m. Conclusions: Old-growth forests at higher elevations are threatened by deforestation, consequently these remaining fragments must be preserved because of their storage capacity for biomass and their ability to mitigate climate change.Background: Tropical montane forests are important reservoirs of carbon and biodiversity but are threatened by deforestation and climate change. It is important to understand how forest structure and aboveground biomass change along gradients of elevation and succession. Questions: What are the interactive effect of elevation and two stages of succession on forest structure parameters? Studied species: Tree communities. Study site and dates: Cofre de Perote, Veracruz, Mexico. August to December 2015. Methods: We studied four sites along an elevational gradient (500, 1,500, 2,500, and 3,500 m). At each elevation and each forest type, we established five 20 × 20 m plots (n = 40 plots). Within each plot, we measured stem density, mean diameter at breast height (dbh), and tree height and derived basal area and aboveground biomass (AGB). Results: AGB peaked at 2,500 m and was significantly related to elevation and succession, with higher values in old-growth forests than in secondary forests at higher altitudes. Lower values of mean dbh and basal area were found at higher elevations. At the lowest elevation, both successional stages had the same values of stem density and AGB. At both lower elevations, secondary forests had higher values of dbh and basal area. There were high biomass stocks in the old-growth forest at 2,500 and 3,500 m. Conclusions: Old-growth forests at higher elevations are threatened by deforestation, consequently these remaining fragments must be preserved because of their storage capacity for biomass and their ability to mitigate climate change