Aim Our goal was to test the hypothesis that ancient humans substantially contributed to shaping the current distribution of Brazil nut (Bertholletia excelsa), an Amazonian tree species that has been important for human livelihoods since pre-Columbian times. We scrutinized the putative association between Brazil nut and Amazonian Dark Earth soils (ADE) and geometric earthworks called geoglyphs, and examined the existence of continental patterns in human footprints on Brazil nut stands.Location Amazon Basin.Methods We carried out a spatially explicit meta-analysis of the variation of Brazil nut stand metrics across the Amazon Basin based on 87,617 density estimates and 488 average stand diameter assessments, and related these to previously published datasets and suitability maps of Brazil nut, ADE and geoglyphs.Results We found consistently higher Brazil nut suitability scores, stand densities and average stand diameters in the vicinities of ADE than at larger distances, regardless of their position along a gradient from south-western to north-eastern Amazonia. For geoglyph sites such a pattern was only found for Brazil nut habitat suitability scores. The available data further revealed an accumulation of Brazil nut stands with increasing densities and average diameters from south-western to central and eastern Amazonia.Main conclusions Our findings suggest that the chance of encountering Brazil nut stands bearing the marks of past human influences increases from south-western to central and eastern Amazonia. In south-western Amazonia, the regeneration of Brazil nut seems to have been controlled predominantly by natural processes, whereas in central and eastern Amazonia, anthropogenic disturbance has been more important since pre-Columbian times. However, it remains challenging to disentangle human influences on the distribution and abundance of Brazil nut from existing environmental gradients across the Amazon Basin. In general, the results of this meta-analysis bode well for the future coexistence of Brazil nut with different forms of contemporary human land use.

Understanding the factors that underlie the production of non-timber forest products (NTFPs), as well as regularly monitoring production levels, are key to allow sustainability assessments of NTFP extractive economies. Brazil nut (Bertholletia excelsa, Lecythidaceae) seed harvesting from natural forests is one of the cornerstone NTFP economies in Amazonia. In the Peruvian Amazon it is organized in a concession system. Drawing on seed production estimates of >135,000 individual Brazil nut trees from >400 concessions and ethno-ecological interviews with >80 concession holders, here we aimed to (i) assess the accuracy of seed production estimates by Brazil nut seed harvesters, and (ii) validate their traditional ecological knowledge (TEK) about the variables that influence Brazil nut production. We compared productivity estimates with actual field measurements carried out in the study area and found a positive correlation between them. Furthermore, we compared the relationships between seed production and a number of phenotypic, phytosanitary and environmental variables described in literature with those obtained for the seed production estimates and found high consistency between them, justifying the use of the dataset for validating TEK and innovative hypothesis testing. As expected, nearly all TEK on Brazil nut productivity was corroborated by our data. This is reassuring as Brazil nut concession holders, and NTFP harvesters at large, rely on their knowledge to guide the management of the trees upon which their extractive economies are based. Our findings suggest that productivity estimates of Brazil nut trees and possibly other NTFP-producing species could replace or complement actual measurements, which are very expensive and labour intensive, at least in areas where harvesters have a tradition of collecting NTFPs from the same trees over multiple years or decades. Productivity estimates might even be sourced from harvesters through registers on an annual basis, thus allowing a more cost-efficient and robust monitoring of productivity levels.

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Enterolobium cyclocarpum is a characteristic legume tree species of seasonally dry tropical forests (SDTFs) of Mesoamerica and northern South America typically used in silvopastoral and agroforestry systems. Remaining populations of E. cyclocarpum in Colombia are severely fragmented owing to the highly degraded state of SDTF in the country, posing threats to both their in situ persistence and their usefulness as seed sources for future planting efforts. We genotyped E. cyclocarpum populations at nine sampling sites across a latitudinal gradient of SDTF in Colombia by means of eight nSSR markers to elucidate the species diversity distribution in the country. Our data suggest that a deep divide seems to have existed between Caribbean and Andean populations of E. cyclocarpum in Colombian SDTF that may date back to the last glacial maximum (*21,000 BP), or longer. However, we only found evidence of genetic differentiation between trees from the southern Cauca River valley and populations at more northern locations. All the latter populations showed signs of admixture which may be the result of human-influenced

El Bosque Seco Tropical (bs-T) es uno de los ecosistemas más degradados de Colombia requiriendo acciones urgentes para la conservación de sus relictos remanentes y la restauración de áreas degradadas. La diversidad genética es una herramienta fundamental para identificar áreas prioritarias de conservación in situ, y evaluar la calidad de las poblaciones como fuentes de semilla para su uso en la restauración. Aquí se presentan los resultados de una caracterización genética realizada con marcadores moleculares ISSRs (Inter Simple Sequence Repeats) en 251 individuos de cuatro especies clave del bs-T Colombiano: Bursera simaruba, Platymiscium pinnatum, Hura crepitans y Caesalpinia ebano. Las poblaciones más diversas para las cuatro especies se encontraron en la región del Caribe y en el enclave del Cañón del Chicamocha. Platymiscium pinnatum y B. simaruba también mostraron valores altos de diversidad en el valle del río Cauca y el desierto de La Tatacoa, respectivamente. Además, se evidenció estructura genética en las cuatro especies que podría estar asociada a las transformaciones históricas del bs-T en los periodos geológicos del Pleistoceno y el Holoceno. Finalmente, se identificaron fuentes de semilla en cada región para cada especie y entre ellos se destacan el norte Caribe y el área del enclave del Cañón del Chicamocha, por su riqueza y particularidad genética.