Societal Impact Statement: The Brazil nut is a highly valuable non‐timber forest product from a wild, hyperdominant, emergent tree species that is increasingly vulnerable and exposed to habitat degradation. We provide evidence for how Brazil nut genetic resources are negatively affected by forest degradation and discuss the consequences of this for reproductive success. To avoid negative effects of genetic erosion and inbreeding, we discuss the need to cease large‐scale forest conversion and to promote landscape connectivity. This could support gene flow, maintain genetic diversity across individuals reproducing in clustered patterns and contribute to securing the long‐termed reproductive viability and resilience of this high socio‐economically and ecologically valuable species.Summary: Ecosystem degradation in the Amazon drives this biodiverse rainforest toward an ecological tipping point. Sustainable management and restoration of degraded rainforest therein are central to counteract this crisis. One hyperdominant, keystone species of high ecological and socio‐economic value, the Brazil nut tree, offers additional benefits as a major carbon sink and a nutritional source of the most prominent globally traded non‐timber forest product. Despite Brazil nut trees being protected by conservation regulation, forest degradation threatens sufficient gene‐flow among Brazil nut tree populations. This has impacts on the reproductive success, genetic diversity, and consequently on the resilience of this species to environmental change. We used 13 microsatellite loci to explore the consequences of forest degradation on the reduction in genetic diversity of Brazil nut populations. We examined the clustering of genetically related individuals as fine‐scale genetic structure (FSGS) and the variation in genetic diversity and inbreeding across adult trees and seedlings along a categorized forest‐degradation gradient ranging from conserved to degraded areas. In addition, we applied direct and indirect approaches to estimate contemporary pollen‐mediated gene flow. We found significant levels of FSGS, comparable to other similar tropical tree species. Brazil nut seedlings had consistently lower genetic diversity and higher inbreeding than adults, significantly associated with the degree of forest degradation of their origin. We observed limited pollen dispersal, differential patterns in pollen heterogeneity, and disproportionate paternal‐assignment rates from few individuals shaping the effective population size in our dataset. We discuss how this evidence for reproduction vulnerability may affect the genetic resources and undermine the resilience of this ecological and socio‐economic system in Peru.

Similarly to most breeding programs of native species, camu-camu (Myrciaria dubia (Kunt) McVaugh) improvement is also restricted, due to the scarcity of research results. In this situation, the prospection, collection and conservation of germplasm in genebanks ensure successful selection and breeding studies of the species. In this sense, the purpose of this study was the intraspecific characterization of the biometric variability in fruits of native camu-camu populations of the State of Roraima, in the northern Amazon region. Of 16 populations, 247 sub-samples were evaluated. Analyses were performed with the multivariate technique of principal components and hierarchical clustering, to determine the variables with highest intraspecific variability for the studied traits. The populations found in the lower Rio Branco region performed best for the studied traits, indicating the great potential of the region as a reservoir of promising subsamples for future breeding programs of the species in the northern Amazon.

This research examined how edaphoclimatic variations are related to dendrometric variables of the Tara tree in natural and agroforestry systems in Cajamarca, Peru. Evaluations followed three approaches: (a) principal components analysis (PCA) with environmental factors and altitude classes with 1 °C of temperature variation for edaphic and dendrometric variables; (b) evaluation of possible differences by the bootstrap method for the different variables in the PCAs; and (c) correlation analysis between plant density, plant and crown height, stem and crown diameter, and the number of stem branches with the physical and chemical attributes of the soil and with air temperature. In the altitudinal gradient from 2021 to 3007 ± 7 m, the temperature ranged from 19.8 to 13.4 ± 0.4 °C; the soils possessed alkaline pH, high organic matter (OM), K and CEC, lower contents of CaCO₃, N, P, K, B, Cu, Fe, Mn, and Zn. The soil properties with the most significant contribution to PCAs were OM, CEC, N content, and sand, with no variation among environments but among altitudes. None of the dendrometric variables varied as a function of altitude and temperature in PCAs run in the natural environment. However, in the agroforestry environment, there was a greater crown diameter, and tree and crown height in the 2185 m altitude class associated with Medicago sativa. In contrast, the opposite behavior was found in these variables and in the altitude class 2798 m associated with low Fe content, and already in the altitude class at 3007 m, a larger stem diameter is associated with higher levels of CaCO₃. The anthropic effect on the agroforestry environment did not significantly alter the soil’s CEC, OM, N, and sand. Tara’s crown diameter and tree height appeared higher in agroforestry environments. The variations of Fe and CaCO₃ in the soil might have influence on the development of Tara individuals in natural and agroforestry environments. It is important to carry out further studies for a better understanding of the relationship between the production of Tara pods and soil fertility in altitudinal variation, aiming to improve the income and employment of family farmers who exploit Tara in the Peruvian Andes.

Camu camu es una fruta nativa de la Amazonía, que llama la atención por el alto contenido de vitamina C (6,116 mg/ 100 g de pulpa), está en proceso de domesticación, por lo cual se está investigando un método de propagación vegetativa que permita avanzar en el proceso de mejoramiento genético. El objetivo de este trabajo fue evaluar la capacidad rizogénica de plantas matrices promisorias de camu camu "Myrciaria dubia (Kunth) McVaugh" según el aumento del número de hojas, mediante la técnica de estacas herbáceas en cámaras de subirrigación. El ensayo fue conducido mediante un Diseño de Bloques Completamente al Azar (DBCA) con arreglo factorial 9Ax3B, con 3 repeticiones y 15 estacas por unidad experimental. El factor A, estuvo constituido por nueve plantas matrices y el factor B: pares de hojas con 3 niveles: 1; 2 y 3 pares. El enraizamiento fue evaluado después de 90 días. Se observó que existió interacción estadística significativa para las variables: porcentaje de enraizamiento, longitud y número de raíces. Para las variables porcentaje de callo y porcentaje de mortalidad se encontró efecto de la planta matriz y pares de hojas. Los resultados muestran que el porcentaje de enraizamiento estuvo influenciado por efectos intrínsecos adherentes a la variabilidad genotípica de las plantas matrices, presentando un alto grado de dispersión, que osciló entre 91,11 % y 0,00 %, mostrando una alta variabilidad y marcada influencia de la planta matriz sobre el proceso de rizogénesis, influyendo de manera altamente significativa en el enraizamiento. Con respecto al área foliar, estacas con 2 y 3 pares de hojas, independiente de la planta matriz, presentaron mayor capacidad de enraizamiento. Con base en estos resultados se concluye que el efecto de la variabilidad genotípica y el área foliar influyen de manera altamente significativa en el proceso de rizogénesis de estacas herbáceas de camu camu.

En este trabajo es estudiado el efecto de dos densidades de siembra de la palmera aguaje (Mauritia flexuosa L.f.) sobre su crecimiento en altura; cuantificamos la proporción de plantas según sexo y determinamos los requerimientos ecológicos de iluminación y forma de copa del aguaje. El estudio se desarrolló en dos subparcelas con diferente densidad de siembra que fueron monitoreadas por 6 años después de 6 años de haber sido plantadas. Los resultados muestran que los individuos presentan mayor altura promedio y por lo tanto mayor crecimiento a mayor densidad de siembra. Es así que a los 12 años de establecidas las plantaciones, los individuos tuvieron en promedio 15.28 m y 13.1 m de altura a densidades de siembra mayores y menores, respectivamente. La proporción de palmeras fértiles se fue incrementando con el tiempo, siendo por lo general mayor a bajas densidades e incrementando en el tiempo la presencia de plantas femeninas. Existe una marcada competencia entre las copas de las palmeras por requerimientos de luz en las categorías buena y aceptable, por lo que se recomienda continuar con la evaluación y analizar el comportamiento futuro de las palmeras.