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Fue determinada la variabilidad genética poblacional de la castaña Bertholletia excelsa en la región de Madre de Dios, mediante el análisis de 11 marcadores microsatélites en un total de 108 árboles. Los resultados globales mostraron una gran diversidad alélica (89 alelos, con una media de 8.09 alelos por locus), a nivel poblacional la mayor riqueza alélica fue encontrada en Iberia (AR = 4.82) y la menor en Itahuania (AR = 3.64), estas mismas localidades fueron las únicas que presentaron exceso de heterocigotos. Los resultados del análisis factorial de correspondencia (AFC) muestra una fuerte sobreposición genética entre la mayoría de las localidades analizadas. Los resultados del índice de Fijación (Fst) muestra que las localidades de Iñapari y Iberia están más relacionadas entre sí (Fst = 0.048), pero ligeramente diferenciadas con las demás localidades (los valores de Fst con las demás poblaciones variaron entre -0.001 a 0.193). El dendrograma basado en la distancia genética de Nei (1978) muestra que las 11 localidades se encuentran conformando tres agrupaciones genéticas diferentes, (A): Amigos, Pukiri, Itahuania y Manuripe; (B): Heath, Tambopata, Virgen del Carmen, Pariamanu, Iberia e Iñapari; y (C) conformada solo por la localidad de Alerta. Las agrupaciones dentro de los clusters podrían ser atribuidos a las escasas barreras físicas entre las localidades dentro de cada cluster, en tanto que las diferenciaciones entre los clusters podrían estar relacionado a la presencia de ríos entre estas agrupaciones, los cuales podrían constituir barreras físicas infranqueables para el flujo de genes entre estas agrupaciones.

Bertholletia excelsa é uma espécie arbórea economicamente importante no Peru, Brasil e Bolívia. Na Amazônia peruana, a produção de mudas é um gargalo enfrentado por concessionários para o reflorestamento. Assim, o objetivo deste trabalho foi avaliar o crescimento inicial e a qualidade de mudas de B. excelsa em dois ambientes de produção. Trinta dias após a germinação as mudas foram transplantadas para tubetes de 115 cm³ com substrato padrão para em seguida serem arranjadas em dois ambientes a 60% de sombreamento. O experimento foi inteiramente casualizado com os tratamentos "viveiro florestal" (T1) e "câmara de sub-irrigação" (T2) com quatro repetições de 10 plantas cada. ANOVA seguida pelo teste de Tukey foram aplicados sobre as médias (p < 0,05). O ambiente de produção teve efeito no desenvolvimento de mudas de B. excelsa. Maiores taxas de crescimento em altura, massa seca da parte aérea, massa seca da raiz e massa seca total foram observadas no T2. Mudas de B. excelsa produzidas na câmara de sub-irrigação apresentaram maiores índices de qualidade de Dickson com 135 dias. Made available in DSpace on 2020-06-22T19:16:19Z (GMT). No. of bitstreams: 1 11837-30746-1-PB.pdf: 569360 bytes, checksum: aeb97d0a02a3ec7408ec6d361ebf09cb (MD5) Previous issue date: 2020

Ecosystem services of Amazonian forests are disproportionally produced by a limited set of hyperdominant tree species. Yet the spatial variation in the delivery of ecosystem services by individual hyperdominant species across their distribution ranges and corresponding environmental gradients is poorly understood. Here, we use the concept of habitat quality to unravel the effect of environmental gradients on seed production and aboveground biomass (AGB) of the Brazil nut, one of Amazonia’s largest and most long-lived hyperdominants. We find that a range of climate and soil gradients create trade-offs between density and fitness of Brazil nut trees. Density responses to environmental gradients were in line with predictions under the Janzen–Connell and Herms–Mattson hypotheses, whereas tree fitness responses were in line with resource requirements of trees over their life cycle. These trade-offs resulted in divergent responses in area-based seed production and AGB. While seed production and AGB of individual trees (i.e., fitness) responded similarly to most environmental gradients, they showed opposite tendencies to tree density for almost half of the gradients. However, for gradients creating opposite fitness-density responses, area-based seed production was invariable, while trends in area-based AGB tended to mirror the response of tree density. We conclude that while the relation between environmental gradients and tree density is generally indicative of the response of AGB accumulation in a given area of forest, this is not necessarily the case for fruit production., Frontiers in Plant Science, 12, ISSN:1664-462X

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., Plants, People, Planet, 3 (2), ISSN:2572-2611

1. Forest landscape restoration (FLR) has gained momentum globally and guidance is needed to identify those species, sites and planting methods that increase restoration success. Incorporating native Non-Timber Forest Product (NTFP) species in FLR approaches provides an opportunity to simultaneously deliver ecological and economic benefits. The Brazil nut tree is one of the most valuable Amazonian NTFP species and could fulfil a cornerstone role in Amazon FLR. However, the factors defining establishment success within Brazil nut restoration activities remain unknown. 2. Here, we evaluate the effect of management practices, restoration site (pastures, agroforestry, secondary forest and canopy gaps in old growth forest) and environmental conditions on the establishment success (tree growth, survival and fruit production) of Brazil nut restoration projects implemented by smallholders in the Peruvian Amazon. We performed a field study at 25 restoration sites of 1–38 years in age, where we conducted measurements on 481 trees and interviewed 21 smallholders. We used mixed effect models to identify drivers of performance. 3. Twenty years after planting, diameter growth in secondary forests was 38%, 34%, and 24% higher than in canopy gaps, pastures, and agroforestry sites, respectively. Survival rate was similar for trees planted in pastures and secondary forests, but 15–20% higher there than trees planted in agroforestry sites, and 7–12% higher than in canopy gaps. Fruit production was 262% higher for reproductive trees in secondary forest sites compared to pastures, but production probability did not differ between restoration sites. These results show that secondary forests are the most suitable sites for planting Brazil nut trees. 4. In addition to restoration site effects, we also found significant effects of management practices. Survival rate increased with application of fire for clearing and weeding and economic investments and decreased with potentially inefficient herbivore protection. Fruit production was lower for trees planted further away from smallholders’ homes. These results show that smallholders’ management has a substantial effect on establishment success. 5. Our findings suggest a significant importance of post-planting maintenance of trees to increase success of FLR projects. Further, our study shows that evaluation of past restoration activities can guide future forest restoration in tropical landscapes., Forest Ecology and Management, 498, ISSN:0378-1127, ISSN:1872-7042

The low natural regeneration of the Brazil nut (Bertholletia excelsa) in the Madre de Dios region of Peru is a major concern for the conservation and sustainable use of this species which sustains one of the cornerstone non-timber forest product economies in Amazonia. The Brazil nut is a gap-dependent, long-lived pioneer species that has been shown to regenerate more effectively in fallows than in mature forests. Aside from light and nutrient availability, recruitment success of the species might also be influenced by conspecific negative distance-dependent (CNDD) processes as shown for a myriad of other tropical tree species, but to date has not been studied in the Brazil nut. We measured Brazil nut recruitment in forty 150 × 10 m2 transects (totaling 6 ha), proportionally laid out in mature forest and fallow land. We found a higher likelihood of regeneration in fallows than in mature forest, which was mainly due to more successful transitioning from seedlings to saplings in fallows. Recruitment rates in fallows increased with the number of fire events occurring over the past 12 years, largely owing to the accumulation of resprouting individuals, but this positive correlation was only observed up to three fire events. We observed CNDD recruitment of the Brazil nut in fallows but not in mature forest, suggesting that pests and diseases might also condition Brazil nut recruitment. Our findings suggest that a better management of fallow land and more controlled use of fire in neighboring land uses could be a cost-effective manner to create Brazil nut rich forests through natural regeneration. On the other hand, the absence of high density Brazil nut stands in mature forests in Madre de Dios might mean that the impact of ancient humans there has been more limited than in other Amazonian regions.

Bertholletia excelsa, conhecida como castanha-do-brasil, é uma espécie arbórea economicamente valiosa na Amazônia. Sementes de B. excelsa aparecem como um dos produtos florestais não-madeireiros mais importantes na Bolívia, Brasil e Peru. No entanto, estas sementes possuem dormência fisiológica, o que torna a germinação lenta, irregular e frequentemente em baixas percentagens. Tal característica biológica representa um gargalo para a produção de mudas de alta qualidade. Em um experimento em Puerto Maldonado, Peru, dez frutos foram coletados por indivíduo em 15 árvores de B. excelsa em cada uma de duas áreas: um plantio experimental e uma floresta nativa. Várias variáveis relacionadas à biometria de frutos, germinação, crescimento inicial e índices de qualidade de mudas foram mensuradas no sentido de comparar mudas de B. excelsa produzidas por sementes originadas de duas áreas e também quanto à posição de sementes no fruto, inferior e superior. Comprimento e diâmetro do fruto apresentaram baixa variação e a maioria dos frutos teve forma achatada. As sementes foram mais abundantes na posição inferior (média = 12,9 ± 2,2) do que na posição superior (média = 6,5 ± 2,1) no interior do fruto. Considerando o número total de sementes por fruto, as médias foram 9,4 ± 3,2 e 17,5 ± 3,7 para floresta plantada e nativa, respectivamente. A germinação completa não diferiu entre as áreas (F1, 56 = 1,945, p = 0,169). Mudas produzidas com sementes de plantios e da posição inferior no interior do fruto apresentaram maiores índices de qualidade. Made available in DSpace on 2019-08-29T01:07:14Z (GMT). No. of bitstreams: 1 6223180631PB.pdf: 1680058 bytes, checksum: 71b8a96170f8a271e49a69e56a6923f6 (MD5) Previous issue date: 2019

Gold mining is the largest source of mercury (Hg) pollution worldwide. The discharge of mercury in the environment bears direct human health risks and is likely to increase cascading effects throughout local food chains. In the Peruvian Amazon the mining process consists of slashing and burning trees, followed by extraction of gold-bearing sediment, amalgamation with Hg and gold recovery, leading each year to the degradation of 6,000-10,000 ha and the release of 180 metric tons of Hg per year to the enviroment. The purpose of this study was to determine soil Hg levels in soils of abandoned alluvial gold mine spoils and undisturbed forest in the Madre de Dios region, the epicenter of alluvial gold mining in Peru. We selected gold mine spoils of the two most important technologies locally applied for gold extraction, i.e., Minimally Mechanized Mining (MMM) and Highly Mechanized Mining (HMM), in the native communities of Laberinto and Kotzimba, respectively. We collected 127 and 35 soil samples (0-20cm depth) from potentially contaminated sites and undisturbed forest, respectively. Physicochemical analysis and determination of Hg levels were determined for all soil samples. None of the samples had Hg concentrations above Peruvian, Canadian and British Environmental Quality Standards for Agricultural Soil (6.6mg/kg). Hg levels in MMM and HMM were not significantly different between the two areas. The main variables explaining variation of soil Hg concentrations were the vegetation cover, soil organic matter, soil pH and clay particle content, which explained up to 80% of data set variation. Surprisingly, highest Hg concentrations were found in untouched old-growth forest bordering the mine spoils, but there was also a trend of increasing Hg concentrations with the regenerating vegetation. Our findings suggest that Hg concentrations in old mine spoils are low and shouldn’t stand in the way of efforts to restore soil conditions and develop sustainable land uses. However, it is urgent to end the use of Hg in mining operation to decrease human and environmental risks.

La diversidad genética poblacional de Bertholletia excelsa “castaña” fue estimada en siete localidades del departamento de Madre de Dios. Se colectaron un total de 164 muestras, las cuales fueron evaluadas con seis loci microsatélites. Todos los loci microsatélites resultaron polimórficos, reportándose un total de 47 alelos, con una media de 7.83 por locus. Los resultados de AFC, SAMOVA (98.06% de la variación se encuentra dentro de las localidades y solo 2.24% entre ellas) y distancia genética (distancia promedio = 0.017), mostraron que las siete localidades evaluadas presentan poca diferenciación genética entre ellas; presentado un elevado flujo genético demostrado en los resultados de Nm que variaron de 6.26 al infinito. También, los resultados globales de F (0.024), ST R (0.045) muestran una débil diferenciación genética entre las poblaciones. En términos generales, cada localidad ST presenta una amplia variabilidad genética con pocas diferencias entre ellas. Considendo el conjunto de localidades como una única población no se observa diferencia a la panmixia (Ho= 0.68, He= 0.69, F = 0.01). Los resultados is obtenidos tanto dentro de las localidades como entre ellas pueden ser atribuidos a las escasas barreras físicas entre las localidades, un tiempo de generación alto y una duración de vida alta de los árboles (numero eficiente alto) y un sistema de reproducción alogamico de la castaña.

En este estudio, se presenta la capacidad de respuesta de Bertholletia excelsa a una aplicación localizada de nutrientes con fuentes de nitrógeno, fósforo y potasio en suelos ácidos con cuatro niveles de urea, superfosfato triple y cloruro de potasio, respectivamente. Los resultados muestran diferencias significativas (P

A falta de opções tecnológicas de concessionários de florestas para a produção de mudas de espécies nativas na Amazônia peruana é um gargalo para o reflorestamento na região. Neste estudo, uma nova tecnologia de produção de mudas de baixo custo e acessível a produtores foi desenvolvida. Assim, o objetivo neste trabalho foi avaliar a eficiência do uso de baldes como microambientes e substratos para o crescimento inicial de plântulas de Bertholletia excelsa. Aos 40 dias após a emergência, as plântulas foram repicadas para tubetes com capacidade de 115 cm³, contento um substrato padrão composto por areia + serragem + serragem carbonizada na proporção (1:1:1 v/v). Posteriormente, os tubetes foram acondicionadas em baldes (microambientes) com telado a 100% de sombra. O delineamento experimental foi inteiramente ao acaso e os tratamentos foram: T1 = areia, T2 = areia + serragem, T3 = casca de castanha decomposta e T4 = solo de floresta. O substrato T2 favoreceu o comprimento de parte aérea, raiz, número de folhas, massa seca da parte aérea, raízes e total, além do índice de esbeltez de mudas de B. excelsa. A qualidade das mudas de B. excelsa produzidas em microambientes foi semelhante entre os tratamentos, independente do substrato utilizado. Made available in DSpace on 2019-09-19T00:35:03Z (GMT). No. of bitstreams: 1 Dionisio2019ProductionofBertholletiaexcelsa.pdf: 1329865 bytes, checksum: a36d753a393d5a2d7ad6afd1298c1928 (MD5) Previous issue date: 2019