Improving productivity while maintaining ecological complexity remains a central challenge for sustainable intensification in tropical agroforestry systems. Production gap analysis has emerged as a key method for diagnosing the difference between actual and attainable production, yet applications to individual tree scales in heterogeneous perennial systems remain scarce. The clove tree ( Syzygium aromaticum ), whose buds constitute Madagascar's second-largest export crop, exhibits strong inter-annual and intra-field production variability driven by endogenous flowering cycles and climatic fluctuations. A total of 126 trees were monitored over two contrasting seasons (2024 and 2025), integrating exhaustive harvest measurements, dendrometric variables, drone-derived competition indices, and flowering intensity assessments. Attainable production and production gaps were estimated using stochastic frontier analysis, allowing simultaneous estimation of structural determinants and management drivers of inefficiency. Here we show that production gap analysis at the tree scale can be applied to irregular-flowering perennial crops embedded in structurally complex agroforestry systems. Mean observed production of 3.1 kg tree⁻¹ against a mean attainable production of 17.4 kg tree⁻¹ yields an average production gap of 81.8%, substantially larger than those reported for intensively managed perennial crops. Doubling estimated crown lateral surface area increased attainable production by approximately 76%, while trunk diameter exerted an additional positive effect. Production gaps widened from 72% in 2024 to 92% in 2025, coinciding with a rainfall deficit and increased dry spell intensity during the January-April period, when floral bud initiation is thought to occur, although the causal role of these climatic factors requires validation across additional seasons. These findings identify concrete leverage points for improving clove productivity, including crown expansion through adapted pruning and spacing and more frequent weed control in fields where labor and capital allow. More broadly, this work provides a transferable method for diagnosing productivity constraints in irregular-flowering tropical perennial crops in heterogeneous agroforestry landscapes.

Understanding why agroforestry systems are more or less diversified in species is essential for sustaining livelihoods and ecological functions in perennial-crop landscapes. In eastern Madagascar, clove-based agroforestry dominates upland production systems, yet field structure varies markedly across short distances. We clarified the association between landscape-scale rice production capacity and agroforestry diversification–specialisation dynamics in clove-dominated landscapes. We combined tree-inventory data from 54 plots with a quantitative proxy of village-level rice self-sufficiency across three neighbouring villages with contrasting access to irrigated lowlands. Four agroforestry system types, namely complex agroforests, diversified cash-oriented systems, clove-dominated systems and simple parklands, were identified through rule-based classification. Village-level access to irrigated lowlands was strongly associated with their distribution. In rice-surplus villages (Ampahibe, + 15

Understanding why agroforestry systems are more or less diversified in species is essential for sustaining livelihoods and ecological functions in perennial-crop landscapes. In eastern Madagascar, clove-based agroforestry dominates upland production systems, yet field structure varies markedly across short distances. Our objective was to clarify how landscape-scale rice production capacity influences agroforestry diversification–specialisation trajectories in clove-dominated landscapes. We combined tree-inventory data from 54 plots with landscape descriptors and a quantitative proxy of village-level rice self-sufficiency to analyse agroforestry composition across three neighbouring villages with contrasting access to irrigated lowlands. Four agroforestry system types—complex agroforests, diversified cash-oriented systems, clove-dominated systems and simple parklands—were identified through rule-based classification. Village-level access to irrigated lowlands was strongly associated with their distribution. In the valley with extensive irrigated lowlands, agroforestry systems remained highly diversified, integrating fruit, forest and cash-crop species. In intermediate landscapes, mixed configurations occurred. In upland areas where irrigated lowlands were scarce, clove became the main means of securing staple foods through market purchases, corresponding to simplified, clove-dominated systems. Contrary to expectations, within-village topography did not influence perennial species composition. Village-scale differentiation aligned with food-security constraints operating at the household level rather than fine-scale ecological sorting. These findings suggest that contemporary agroforestry configurations result from the interaction between historical trajectories—colonial coffee plantations, farmer-led clove expansion and post-independence enrichment practices—and present-day rice availability, which appears to filter how diversification or specialisation unfolds. Our results highlight that maintaining agroforestry diversity in clove-producing regions depends as much on securing stable rice production systems as on managing perennial-crop markets.

Martinique is a French Caribbean island known across the world for its richly diverse flora and fauna and for its agricultural production (bananas and sugar cane). Until the early 20th century, Martinique was also a producer and exporter of many other commodities, including cocoa, coffee, pepper, and vanilla. These crops have gradually declined and now only supply the local market. However, for some years now, farmers supported by the French Directorate for Food, Agriculture and Forestry have been working to revive an early method of production of these crops by reestablishing agroforestry systems in which crops are grown under shade while maintaining the original forest cover. The study reviews the first attempts to implement these methods for cocoa and vanilla plantations. This research conducted an initial assessment of the technical management of these plots after a few years of implementation, in order to better understand the interests, issues at stake, limiting factors, and prospects that arise with a return to these former practices. Thirteen plots and eleven technical options for agroforestry management were identified. Surveys among farmers indicated the high added value of these products on the local market but also revealed severe constraints arising from working conditions and a difficult environment. Initial economic analyses, according to those surveyed, indicated positive gross margins and revenue per working day from the fifth year and, importantly, a return on investments from the seventh and eighth years of implementation. The study shows that these early agroforestry systems could be promoted in Martinique. Their technical and operational feasibility highlights the potential of a resurgent sector to deliver sound economic returns in the future. In the long term, development of this practice could revive other abandoned crops, reduce fragmentation of forest lands caused by clearing and urban sprawl, promote agroecology through the planting of trees and service plants, and encourage farmers to set up activities with access to a currently undervalued land resource.

La Martinique est une île caribéenne française reconnue mondialement pour sa richesse floristique et faunistique et pour ses productions agricoles (banane et canne à sucre). Jusqu’au début du XXe siècle, elle était aussi productrice et exportatrice de nombreuses autres denrées : cacao, café, poivre, vanille. Ces cultures ont progressivement périclité, assurant juste l’approvisionnement du marché local. Quelques agriculteurs appuyés par la Direction de l’Alimentation, de l’Agriculture et de la Forêt de France (DAAF), ont déjà mis en œuvre une démarche de relance d’un mode ancien de productions agroforestières en réinstallant des systèmes de productions sous couvert forestier. Ces systèmes intègrent des cultures sous ombrage tout en maintenant en place la forêt originelle. L’étude recense les premières tentatives sur des cacaoyères et des vanilleraies. Elle propose un premier bilan de la gestion technique des parcelles après quelques années de mise en place, afin de mieux comprendre les intérêts, les enjeux, les facteurs limitants et les perspectives liés au retour de ces pratiques anciennes. Treize parcelles ont été identifiées. Il en ressort onze itinéraires techniques de gestion agroforestière. Les enquêtes auprès des agriculteurs ont révélé une forte valeur ajoutée des productions sur le marché local. Mais elles montrent aussi les contraintes fortes liées aux conditions de travail et à l’environnement. Les premières analyses économiques à dire d’acteurs ont révélé une marge brute et une valorisation de la journée de travail positives dès la cinquième année, et surtout un retour sur investissement à partir de la septième et huitième année de mise en place. Ce travail montre qu’il est possible de promouvoir en Martinique ces systèmes agroforestiers originaux. La faisabilité illustre le fort potentiel d’une filière renaissante avec de futurs retours économiques solides. À long terme, le développement de cette pratique pourrait relancer d’autres productions délaissées, réduire le mitage des terres forestières lié au défrichement et à l’urbanisation, promouvoir l’agroécologie en favorisant l’implantation d’arbres et de plantes de service, et favoriser l’installation d’agriculteurs avec un accès à une ressource foncière actuellement peu valorisée.

This article explores the significance, challenges, and future prospects of Madagascar’s cash crops: vanilla, cloves, lychees, black pepper and cinnamon. Cultivated by small-scale farmers in biodiverse agroforestry plots, these cash crops have historical importance in Madagascar's export-oriented economy that has seen Madagascar become the world's leading producer of vanilla, the second largest exporter of cloves and essential clove oil, and the leading exporter of lychees to the European market. Despite contributing substantially to the country's exports, farmers remain vulnerable, as the markets for these products are controlled by global food industry giants and are subject to significant price fluctuations. Other factors that contribute towards farmer’s vulnerability include climate change, local security conditions, competition from other producing countries and the introduction of synthetic vanillin. Despite the volatilities, farmers’ income and food security remain tied to these cash crops. Diversification is recommended to ensure better resilience against volatile conditions, including diversification of crops, land management practices, and product uses. By adapting agroforests to integrate a variety of cash crops and food crops, farmers’ income and food security will be protected long-term. Further research on agro-biodiversity management is now needed to continue to mitigate market dynamics and environmental challenges.

Madagascar is a world hotspot of biodiversity, with an endemism rate that reach up to 80%. Therefore, its flora represents a potential reservoir for bio-compounds, the development of which represents a scientific, an economic as well as an environmental challenge. Today, the harmfulness of petrochemical dyes to both human health and the environment is established. An alternative relies on the production of natural dyes trough green chemistry processes. Our research, based on indigenous empirical knowledge of dyers at Madagascar (in Indian Ocean), proposes as a first step to record all Malagasy dye plant species through an ethnobotanical survey and chemical screening of the coloration potential of some plant extracts. In a second step, the most interesting plant extracts (in aqueous ethanolic solution) were selected for a more indepth characterization of the color properties of the raw extracts. Several Malagasy plants species have been identified to have promising coloration potential as alternative sources of dyes or pigments. Two sources of natural yellow and two sources of natural red dyes will be discussed in this study. The plant biomass includes barks of Acridocarpus excelsus and Harungana madagascariensis, leaves of Tectona grandis and roots of Paracarphalea kirondron. The main chemical families identified in these four plant extracts are polyphenols, flavonoids, tannins, xanthonoids and quinonoids. Most of the pigments extracted from these five plants showed very good stability toward pH and high temperatures (up to 200 degrees C). Moreover, some plant extracts also showed high antioxidant and antimicrobial properties. Finally, an acute toxicity test performed using a zebrafish model showed that most of these extracts are less toxic than the usual artificial dyes. It should be noted that very little information has been found in the literature about the composition of roots of the endemic species P. kirondron. HPCL/DAD/MS analysis of the yellow colors extracted from P. kirondron showed a high concentration of different quinonoid pigments with potentially new structures (research in progress in laboratory). The diversity of dye plants from Madagascar is a promising source of natural dyes that can replace the artificial ones. However, the supply of a production chain for these dyes involves the respect for the rights of local actors and the implementation of actions to manage this biodiversity in a sustainable way.

The article reports the AMS (accelerator mass spectrometry) radiocarbon investigation of the historic Grand Baobab of Mahajanga.The largest African baobab of Madagascar exhibits a cluster structure, which consists of 6 fused ordinary stems and of 3 small binding stems.Two samples were collected from the largest stem and from a primary branch, out of which several tiny segments were extracted and dated by radiocarbon.The oldest dated sample segment had a radiocarbon date of 214 ± 17 BP, which corresponds to a calibrated age of 265 ± 25 calendar years.The dating results indicate that the Grand Baobab of Mahajanga is 275 ± 25 years old.

The article discloses the AMS (accelerator mass spectrometry) radiocarbon dating results of the Egg baobab, a superlative Grandidier baobab (Adansonia grandidieri) from the Andomiry Forest, Atsimo-Andrefana region, Madagascar.The investigation of the baobab shows that it consists of 5 perfectly fused stems and exhibits a closed ring-shaped structure with a very large false cavity inside.The calculated overall wood volume of the Egg baobab is 450 m 3 .Two wood samples were collected from the exterior of the stems, out of which nine tiny segments were extracted and dated by radiocarbon.The oldest sample segment had a radiocarbon date of 921 ± 24 BP, which corresponds to a calibrated age of 840 ± 25 years.According to this value the Egg baobab is 875 ± 75 years old.

While agroforestry is promoted in many regions worldwide, limited attention is paid to farmer-led transitions toward agroforestry. Agroforestry systems (AFS) are ubiquitous and structure the landscapes along the east coast of Madagascar. These systems are managed by smallholders and produce a variety of products, some for export (mainly clove products, vanilla, and lychees), others for self-consumption or for sale locally (including fruit, tubers, timber and fuelwood). We compared information in historical documents with data collected in household surveys in 2016 in one village to identify the socio-technical and economic determinants that guided farmers' strategies over a century and led to the current production systems and landscapes. The agricultural policy implemented by the French colonial power, required farmers to produce industrial crops for export. Reluctantly at first, farmers gradually abandoned shifting rice cultivation ( tavy ) to grow cash crops, mainly coffee, paving the way for an economy based on trade and monetization. Later, farmers replaced coffee by clove trees, gradually transforming shifting cultivation into AFS with cloves. Simultaneously, they extended paddy rice cultivation and diversified their AFS in response to economic and climatic disturbances and to more gradual changes, thereby demonstrating their continual responsiveness. Similar dynamics can be observed in many contexts where the colonial powers forced farmers to produce cash crops to supply industries in the metropolitan area, obliging them to diversify their production and cropping systems. Our results provide valuable insights into the multiple drivers of these transitions toward agroforestry and into the complexity of the processes involved.

An inventory of the species in and around the clove agroforestry systems (AFS) on the east coast of Madagascar revealed that none of the currently grown species derive from the native Malagasy biodiversity: the herbaceous and woody plants which comprise planned agrobiodiversity, i.e. are deliberately planted by the farmer, are without exception, introduced species. The associated agrobiodiversity, including plants that grow spontaneously and are protected or tolerated by farmers, is composed of a mix of native and introduced species. This situation, which is paradoxical for an island with a very high level of endemicity is the result of a double process of species introduction. The first is associated with the waves of migration, which, during the past three thousand years or so, allowed colonisation of the island, previously devoid of human occupants. The migrant populations originating from Austronesia and then from Africa, introduced their own crops and associated growing practices and only exploited local biodiversity through gathering, which did not require planting or tending. This situation is therefore the result of a long process of farmers' strategies to manage natural resources in a context of subsistence agriculture. The second process is more recent and is associated with increasing occupation by Europeans from the 16th/eighteenth century onwards, which peaked at the end of the nineteenth century with the French colonisers, who introduced and then developed cash crops (coffee, cloves, vanilla). This long-term retrospective study sheds light on the dynamics at the origin of the biodiversity "melting pot" visible today in the AFS along the east coast of Madagascar. It shows the constant evolution and adaptation of farmers' strategies and cropping systems, but also their historical roots. The cohabitation between introduced and indigenous species, observed today in Madagascar, is found in other AFSs built around an introduced cash crop, in various tropical zones. Knowing the origins and determinants of this cohabitation could be useful to support future evolutions of these cropping systems in the current context of changing agricultural practices in response to ecological and macroeconomic pressures.

It is commonly accepted that species should move toward higher elevations and latitudes to track shifting isotherms as climate warms. However, temperature might not be the only limiting factor determining species distribution. Species might move to opposite directions to track changes in other climatic variables. Here, we used an extensive occurrence data set and an ensemble modelling approach to model the climatic niche and to predict the distribution of the seven baobab species (genus Adansonia) present in Madagascar. Using climatic projections from three global circulation models, we predicted species' future distribution and extinction risk for 2055 and 2085 under two representative concentration pathways (RCPs) and two dispersal scenarios. We disentangled the role of each climatic variable in explaining species range shift looking at relative variable importance and future climatic anomalies. Four baobab species (Adansonia rubrostipa, Adansonia madagascariensis, Adansonia perrieri¸ and Adansonia suarezensis) could experience a severe range contraction in the future (>70% for year 2085 under RCP 8.5, assuming a zero-dispersal hypothesis). For three out of the four threatened species, range contraction was mainly explained by an increase in temperature seasonality, especially in the North of Madagascar, where they are currently distributed. In tropical regions, where species are commonly adapted to low seasonality, we found that temperature seasonality will generally increase. It is, thus, very likely that many species in the tropics will be forced to move equatorward to avoid an increase in temperature seasonality. Yet, several ecological (e.g., equatorial limit, or unsuitable deforested habitat) or geographical barriers (absence of lands) could prevent species to move equatorward, thus increasing the extinction risk of many tropical species, like endemic baobab species in Madagascar.

Clove production in the eastern coastal region of Madagascar is typical of an export crop grown by particularly vulnerable smallholders. Products from clove trees, along with vanilla, account for the largest proportion of Madagascar's agricultural exports. There is a marked contrast between the national economic stakes and the situation of smallholders hampered by fluctuating world market prices, a particularly erratic climate in this cyclone-prone area, and land fragmentation due to high demographic pressure. Clove trees were first introduced by French settlers and grown in monospecific plantations according to their development model. These clove plantations dominate the landscape but appear at first sight to be deteriorating, thus mobilizing R&D actors with the intention of improving the sector. What if it turned out, on the contrary, that farmers had gradually developed, over generations, diverse and diversified clove systems adapted to the prevailing uncertainty? This is what we wanted to test by implementing a method combining farmer surveys and field observations. We assumed that the density of associated and clove trees, the identification of species within these stands, and the clove tree growth status, reflected the past and present dynamics and the sought-after functions. In two Fenerive-Est villages, we analysed findings from a sample of thirty clove plots, and revealed six different types of system in terms of vegetation structure, species combinations and ages. The trend was in favour of clove tree maintenance and renewal, but also diversification of associated tree species and uses of the underlying layers, to the detriment of the per-hectare clove tree density. The systems had also evolved according to the age of the clove trees. Interventions to improve clove production in Madagascar must be designed within the framework of these diversified, multifunctional and evolving systems, without overlooking other derivative components and products.

Les paysages agraires de la côte nord-est malgache sont marqués par des rizières et des systèmes agroforestiers diversifiés, dominés par une ou plusieurs cultures de rente (giroflier, litchi, vanille, café) ainsi que des productions vendues localement et/ou autoconsommées (fruits, café, tubercules, bois). Cette diversification répond à une stratégie d’intensification des systèmes et de diversification des revenus. Les ménages combinent ainsi une résilience directe par l’autoconsommation du riz comme une résilience « économique » indirecte, basée sur la vente des produits de rente dont le revenu permet l’achat du riz manquant et l’amélioration des conditions de vie. Cette stratégie, même si elle dépend des fluctuations des prix sur le marché international, atténue l’impact de ces aléas sur les revenus.

Over the past years, our research on baobabs mainly focused on the largest Malagasy species, namely the Reniala or Grandidier baobab (Adansonia grandidieri Baill.). The biggest A. grandidieri are located in the Morombe area, especially in the so-called Andombiry Forest. This giant forest of Reniala hosts well over 6000 mature individuals, out of which more than 30 have very large sizes, i.e., circumferences over 20 m. We investigated, measured and dated by AMS radiocarbon the largest specimens. We found that all large Grandidier baobabs are multi-stemmed. They mostly exhibit a closed ring-shaped structure, with a false cavity inside. In this architecture, which enables Grandidier baobabs to reach very large sizes, the stems that build the ring typically have similar ages. Here we present the AMS radiocarbon investigation of two large baobabs, A 215 (girth 21.50 m) and A 257 (girth 25.70 m). According to dating results, the baobab A 215 has an age of only 375 years. It consists of four fused stems and has a closed ring-shaped structure. The baobab A 257 has the second largest trunk of all known live Reniala trees. It also exhibits a closed ring-shaped structure, with five fused stems around a false cavity, which has an opening toward the exterior. The dating results indicate that A 257 is around 900 years old.