The dry forest biome covers extensive areas of the global tropics. However, the understanding of these forest formations from both human and biophysical perspectives varies widely both geographically and in terms of disciplinarity. While considerable resources have been made available for the sustainable management of the humid tropical forests, there has been a lack of comparable sustained attention on their dry forest equivalents. This special issue is an attempt to provide further insights into the state of the knowledge of global dry forests, and identify research gaps that could contribute to their long-term sustainability, both for human well-being and ecological integrity.

To provide an inter-continental overview of the floristics and biogeography of drought-adapted tropical vegetation formations, we compiled a dataset of inventory plots in South America (n=93), Africa (n=84), and Asia (n=92) from savannas (subject to fire), seasonally dry tropical forests (not generally subject to fire), and moist forests (no fire). We analysed floristic similarity across vegetation formations within and between continents. Our dataset strongly suggests that different formations tend to be strongly clustered floristically by continent, and that among continents, superficially similar vegetation formations (e.g. savannas) are floristically highly dissimilar. Neotropical moist forest, savanna and seasonally dry tropical forest are floristically distinct, but elsewhere there is no clear floristic division of savanna and seasonally dry tropical forest, though moist and dry formations are separate. We suggest that because of their propensity to burn, many formations termed “dry forest” in Africa and Asia are best considered as savannas. The floristic differentiation of similar vegetation formations from different continents suggests that cross-continental generalisations of the ecology, biology and conservation of savannas and seasonally dry tropical forests may be difficult.

Seasonally Dry Tropical Forests (SDTF) are gaining recognition as a significant biome and poorly conserved tropical biodiversity refuge. Understanding floristic relationships within SDTF is essential for their effective conservation. This study examines the floristic variation within SDTF of the Caatinga Biogeographic Domain, in north-eastern Brazil. SDTF trees, shrubs and arborescent cacti were sampled in six localities in the Brazilian states of Minas Gerais and Bahia. A number of soil chemical attributes were also measured to analyse vegetation-soil relationships across the study sites. Five floristically distinct SDTF communities were delineated. Differences in these communities are attributable to influences from adjacent savanna and rain forest surrounding the study sites, and also to soil properties such as Al3 , base saturation and gravel content. The high species richness of, and species dissimilarity between communities reflect the need for judicious conservation planning for SDTF that account for biodiversity values and forest structural integrity.

Globally, micronutrient deficiencies are more prevalent than calorie and protein deficiencies. In order to address global micronutrient deficiencies, increasing attention is being paid to the nutritional quality of people's diets. While conventional agriculture is key for ensuring adequate calories, dietary quality depends on the consumption of a diverse range of micronutrient rich foods. Many wild foods are rich in micronutrients, particularly fruits, vegetables, and animal source food. As a result there has been increasing interest in the value of wild foods to meeting nutritional requirements.

We review literature on the consumption of wild foods in dry forest areas to assess the current state of knowledge as to how dry forests may contribute to nutrition. We focus on papers that quantify consumption of wild forest foods. Although there is a great deal of literature that lends weight to the notion that dry forests are important for food security and nutrition, we find surprisingly little evidence of direct contributions to diets. Of 2514 articles identified by our search, only four quantify the consumption of wild foods from dry forests, and only one of these puts this consumption in the context of the entire diet. There is a need for research on the nutritional importance of dry forest foods which combines methodologies from nutrition science with an understanding and appreciation of the ecological, social, cultural and economic context.

Dry forests play a significant role if the livelihoods strategies of millions of people, including many of the world's poorest. This paper reviews the role of dry forests in providing goods and services to the rural poor. The review shows that while dry forests are essential, rural communities are engaged in multiple activities that generate income and the economic importance of forests and trees is context specific. Although the majority of households benefit from forest resources, poorer households tend to generate more relative income from forest products than wealthier households. Community forestry, tourism and payment for environmental service (PES) are promising alternative sources of environmental income, but the outcomes for the poorest remain uncertain. Trade in non-timber forest products (NTFP) is often viewed as a last resort and provides the safety net to cope with both environmental and economic shocks, especially for women. Hence, beyond timber, there are few examples of dry forest products that have generated a sustainable source of significant wealth. As such, it seems likely that dry forests will continue to play a more supplementary role in direct poverty alleviation but an increasingly important role as a safety net that prevents the most vulnerable from slipping into increased poverty and food insecurity during times of crisis.

From a broad review of 670 publications on gender and forests, ∼130 were found to address the world's dry forests. These were examined with the intent to extract gendered social, cultural, political and economic patterns of relevance in such forests. Seven interrelated themes recurred in this literature: 1) population pressure, 2) migration, 3) intra-familial and inter-group conflict, 4) hierarchy and significant power differences, 5) strict gender differentiation, 6) commercialization of crops and NTFPs, and 7) fuelwood collection. Based upon these themes, the uniqueness of each situation and the importance of finetuning any approach to local realities to generate outcomes that can benefit women, we propose four promising ways to enhance the prospects for gender equity in dry forest areas: 1) a strengthening of groups and collective action, 2) explicit challenges to traditional gender norms, 3) a focus on products and spaces that interest women, and 4) addressing migration and population issues.

Parmi 670 publications portant sur le genre et les forêts, nous en avons identifié ∼ 130 se concentrant sur les forêts sèches du monde. Nous y avons analysé les principaux enjeux par rapport aux relations de genre dans les sphères socio-culturelle, politique et économique. Sept thèmes communs et interreliés se sont dégagés de cette analyse : 1) la pression démographique, 2) la migration, 3) les conflits inter-familiaux et intergroupes, 4) la hiérarchie et la différence de pouvoir, 5) une différenciation prononcée selon le sexe, 6) la commercialisation des récoltes et des PFNL et 7) la collecte de bois de chauffe. Basé sur ces analyses et tenant compte de l'importance du contexte local dans tout enjeu par rapport au genre, nous proposons quatre voies prometteuses pour favoriser l'égalité des sexes dans les zones de forêts sèches : 1) un renforcement des groupes locaux et des actions collectives, 2) une volonté explicite de remettre en question les normes traditionnelles liées aux genre, 3) un accent sur les produits et espaces d'importance pour les femmes et 4) une approche qui aborde les questions de migration et de population.

A partir de una amplia revisión de 670 publicaciones sobre género y bosques, se encontró que ∼130 tratan los bosques secos del mundo. Éstas se examinaron con la intención de extraer patrones de género sociales, culturales, políticos y económicos relevantes en dichos bosques. En esta literatura son recurrentes siete temas relacionados entre sí: 1) presión poblacional, 2) migración, 3) conflictos intrafamiliares y entre grupos, 4) jerarquía y diferencias significativas de poder, 5) diferenciación estricta entre géneros, 6) comercialización de cultivos y productos forestales no maderables, y 7) recolección de leña. Tomando estos temas como punto de partida, la singularidad de cada situación y la importancia de afinar cualquier acercamiento a las realidades locales con el que generar resultados que puedan beneficiar a las mujeres, proponemos cuatro formas prometedoras de mejorar las perspectivas de equidad de género en las áreas de bosque seco: 1) el fortalecimiento de los grupos y la acción colectiva, 2) cuestionar de manera explícita las normas tradicionales de género, 3) un enfoque en productos y espacios de interés para las mujeres, y 4) tratar las cuestiones de migración y población.

Seasonally dry tropical forests (SDTFs), a varied and extensive ecosystem type in the tropics, are characteristically adapted to seasonal water stress in zones of low rainfall. Land-use change, resource extraction, alien invasives, changes to the atmosphere, and changing fire and climatic regimes may have serious implications for the continued persistence of SDTFs. This paper assesses the extent to which SDTFs may be resilient in the face of these threats, considering their dynamics, community-level characteristics, and functional traits of constituent species. There is evidence that some SDTF biodiversity- and structure-related properties are resistant to low- to moderate-intensity disturbances and have the potential to recover after severe, even chronic, disturbances, at timescales in the order of decades. Although global SDTFs are, on average, not necessarily more resilient than moist tropical forests (MTFs), they may be more resilient to particular disturbances such as fires and drought. SDTFs are vulnerable to regime shifts and there is considerable uncertainty about their future under a changing climate and its interactions with other anthropogenic effects.

Les forêts tropicales à sècheresse saisonnière (SDTFs), un type d'écosystème étendu et varié dans les tropiques, sont adaptées de manière caractéristique au stress dû au manque d'eau dans les zones de faible précipitations. Les changements d'utilisation des terres, l'extraction des ressources, les espèces étrangères envahissantes, Les changements atmosphériques et les régimes climatiques et des feux changeants pourraient avoir des implications sérieuses sur une continuation de la persistance des SDTFs. Ce papier évalue jusqu'où les SDTFs peuvent être résistantes face à ces menaces, en considérant leurs dynamiques, leurs caractéristiques au niveau communautaire, et les traits de fonctionnement des espèces les constituant. Des preuves émergent qu'une partie de la biodiversité et des propriétés liées à la structure des SDTFs est résistante aux dérangements faibles à modérés et que celles-ci détiennent un potentiel de rétablissement après des désordres sévères, et même chroniques, dans une échelle de temps, ordonnée par décennies. Bien que les SDTFs globales ne soient généralement pas nécessairement plus résistantes que les forêts tropicales humides (MTFs), elles pourraient faire preuve d'une plus grande résistance face à certains sinistres tels que le feu et la sècheresse. Les SDTFs sont vulnérables aux changements de régime, et une question considérable demeure quant à leur futur dans un climat changeant et ses interactions avec d'autres effets anthropogéniques.

El bosque seco tropical (BST) es un tipo de ecosistema variado y extenso de los trópicos que se adapta característicamente al estrés hídrico estacional en zonas de baja precipitación. Los cambios de uso del suelo, la extracción de recursos, las especies exóticas invasoras, los cambios en la atmósfera, y los cambios en los regímenes de incendios y del clima pueden tener graves consecuencias para la persistencia continuada del BST. Este artículo evalúa el grado de resiliencia que puede alcanzar el BST frente a estas amenazas, teniendo en cuenta su dinámica, sus características a nivel de comunidad, y los rasgos funcionales de las especies que lo constituyen. Existen pruebas de que algunas propiedades del BST relacionadas con la biodiversidad y su estructura muestran resistencia a perturbaciones de intensidad baja a moderada y tienen potencial para recuperarse después de trastornos graves, o incluso crónicos, en escalas temporales del orden de décadas. Aunque en promedio y a nivel global el BST no es necesariamente más resiliente que el bosque húmedo tropical, si pudiera serlo frente a ciertas perturbaciones como los incendios y la sequía. El BST es vulnerable a los cambios de régimen y existe bastante incertidumbre sobre su futuro en un clima cambiante

Dry forests today are managed following the standards of scientific forestry imported in the tropics in the XIXth century by the colonial empires. The model proved efficient to control deforestation and regulate production but its evolution even after decolonization increased the segmentation between forests and agriculture and the lack of consideration for local knowledge by the forest administration. The process of decentralization of forest management that disseminated in the 1990s aimed at bringing back local communities within the formal management of forests. However the results of this process, often restricted to a simple transfer of tools and techniques, have fallen below expectations. If discourses shifted towards a better recognition of local needs, knowledge and constraints, the day-to-day implementation of participatory forest management in the dry lands remains fraught with administrative inefficiencies and a mistrust of local communities. Sustainable management of dry forests is yet to be invented.

The dry forests in Madagascar represent a remarkable tropical forest ecosystem, occupying almost the entire west slope of the island up to the very northern tip, especially on substrates associated with sedimentary formations. These forests span several woody vegetation types of the island, including (i) the southwestern coastal bushland, (ii) the southwestern dry spiny forest-thicket, and (iii) the western dry forest. These landscapes show a high degree of biodiversity with several centers of endemism hosting a globally unique fauna, with disparities in richness and diversity according to the groups, probably related to paleo-refugia. These landscapes also provide important ecosystem services for various ethnic groups residing along the coast, also hosting the only autochthonous group in Madagascar, the Mikea forest people. In this paper we review the scientific literature to highlight the importance of dry forests socio-ecological landscapes in order to identify knowledge gaps where future research is required to better inform management and policy to better balance conservation and development interests. For this, we recommend the adoption of transdisciplinary approaches that engage with a broad number of stakeholders in order to allow policy adaptations to better cope with current and future changes (e.g., agriculture, energy demands and needs).