Revisiting the ‘cornerstone of Amazonian conservation’: a socioecological assessment of Brazil nut exploitation

The Brazil nut (the seeds of the rainforest tree Bertholletia excelsa) is the only globally traded seed collected from the wild by forest-based harvesters across the Amazon basin. The large geographic scale of Brazil nut exploitation and the significant contributions to local livelihoods, national economies, and forest-based development over the last decades, merit a review of the “conservation-through-use” paradigm. We use Elinor Ostrom’s framework for assessing sustainability in socioecological systems: (1) resource unit, (2) users, (3) governance system, and (4) resource system, to determine how different contexts and external developments generate specific conservation and development outcomes. We find that the resource unit reacts robustly to the type and level of extraction currently practiced; that resource users have built on a self-organized system that had defined boundaries and access to the resource; that linked production chains, market networks and informal financing work to supply global markets; and that local harvesters have used supporting alliances with NGOs and conservationists to formalize and secure their endogenous governance system and make it more equitable. As a result, the Brazil nut model represents a socioecological system that may not require major changes to sustain productivity. Yet since long-term Brazil nut production seems inextricably tied to a continuous forest cover, and because planted Brazil nut trees currently provide a minimal contribution to total nut production basin-wide, we call to preserve, diversify and intensify production in Brazil nut-rich forests that will inevitably become ever more integrated within human-modified landscapes over time.     

Age and Growth Patterns of Brazil Nut Trees (Bertholletia excelsa Bonpl.) in Amazonia,Brazil

Various techniques have been used to estimate the age of Brazil nut trees (Bertholletia excelsa Bonpl.), but these techniques produce large discrepancies. Here, we first verified that two individuals of known ages from a plantation in central Amazonia, Brazil, have a congruent number of growth rings. The indexed average tree‐ring curve was significantly correlated with total precipitation during the rainy season (November–June) over a 50‐yr period, confirming the annual nature of the tree rings. Second, we analyzed Brazil nut trees from two populations in the Trombetas (eastern Amazon) and Purus (central Amazon) regions, performing tree‐ring analysis to estimate tree age and diameter increment rates. We compared age–diameter relationships, mean passage time through 10‐cm diameter size classes, and growth trajectories of individual trees. The maximum age of Brazil nut trees analyzed was 361 yr in the Purus and 401 yr in the Trombetas. Trees at the Purus site had higher mean diameter increment rates and showed more variation compared to trees at the Trombetas site. Individual growth trajectories show that the majority of trees attained the canopy by direct growth, while a smaller number passed through one release or one suppression event before becoming established in the canopy. None of the trees passed through multiple release and suppression events. The age estimations presented here are comparable to previous tree‐ring analyses for the species, and the observed growth patterns support earlier work indicating B. excelsa as a gap‐dependent tree species.     

Population Structure of Brazil Nut (<Emphasis Type="Italic">Bertholletia excelsa,</Emphasis> Lecythidaceae) Stands in Two Areas with Different Occupation Histories in the Brazilian Amazon

Here we hypothesize that the intensity of disturbances caused by human activities in Brazil nut stands (castanhais) is positively related with the regeneration of Brazil nut trees (Bertholletia excelsa H.B.K., Lecythidaceae) and consequently with a younger population structure of this species. In order to test this hypothesis we compared the population structure of Brazil nut trees in two areas of the Brazilian Amazon with different histories of land usage by humans. Archeological and historical data suggest that the region surrounding the Trombetas River was densely occupied in pre-Columbian times and experienced depopulation after European contact with Amerindian populations, especially in the 16^th century. The 25 Brazil nut stands sampled in this region were dominated by old B. excelsa trees and had scarce recruitment in the understory. These very mature stands likely owe their origins to the interval between the depopulation of the indigenous peoples in the 16^th-17^th centuries and the establishment of quilombos at the beginning of the 19^th century. The second study area was in the vicinity of the Madeira River (Capanã Grande Lake), where the castanhais were more accessible and disturbed. In this site, a younger population structure and abundant regeneration of B. excelsa were observed in the 10 sampled stands. Historical data from this region indicate that indigenous populations were replaced gradually beginning in the 18^th century, with no evidence of severe depopulation. We suggest that the different historical and contemporary land use patterns contributed to the current contrasting population structures of the castanhais at the two locations. The data also support the idea that the castanhais, even the ones considered to be pristine and “native” forests, result from anthropogenic influences. We found no evidence to support restrictions on seed harvesting as a means to improve regeneration rates of Brazil nut stands.     

Social Geomatics: Participatory Forest Mapping to Mediate Resource Conflict in the Bolivian Amazon

This paper describes a participatory mapping method field tested with agro-extractive settlements in the Bolivian Amazon. A regional transition from customary to formal property rights resulting from sweeping 1996 land tenure reforms has led to confusion and conflicts over resource rights, a problem compounded by recent high market prices for Brazil nuts. In response to community requests to clarify resource rights to Brazil nut trees, CIFOR offered to train community members to map trees, trails and other key features themselves. This experience indicates that local residents can map their resources in an effective and efficient way and in the process gather necessary information to mediate competing claims, demonstrate their legitimate resource claims to external stakeholders and make management decisions. We argue that maps and properties are more likely to be seen as legitimate reflections of de facto rights if local stakeholders are involved as a group from the outset.     

Population Density and Home Range Size of Red‐Rumped Agoutis (Dasyprocta leporina) Within and Outside a Natural Brazil Nut Stand in Southeastern Amazonia1

This study examined whether the population density and home range size of red‐rumped agoutis were affected by the spatial distribution of Brazil nut trees, at the Pinkaiti Research Station, in eastern Amazonia. Agouti densities in a Brazil nut grove were two‐fold higher and home ranges were half the size than those outside it. This indicates that the large supply of Brazil nuts results in higher densities and smaller home ranges of agoutis in this seasonally dry Amazonian forest.     

A Lepidopteran defoliator attack on Brazil nut trees (Bertholletia excelsa) in Central Amazonia, Brazil

This paper describes a severe outbreak of a Lepidopteran defoliator, Lusura altrix (Stoll 1782), on Brazil nut trees in Central Amazonia. The pest outbreak appeared to succeed abnormal weather conditions, and defoliation was sufficient to disrupt normal phenological patterns.     

Parallel host shifts in a bacterial plant pathogen suggest independent genetic solutions

While there are documented host shifts in many bacterial plant pathogens, the genetic foundation of host shifts is largely unknown. Xylella fastidiosa is a bacterial pathogen found in over 600 host plant species. Two parallel host shifts occurred—in Brazil and Italy—in which X. fastidiosa adapted to infect olive trees, whereas related strains infected coffee. Using 10 novel whole-genome sequences from an olive-infecting population in Brazil, we investigated whether these olive-infecting strains diverged from closely related coffee-infecting strains. Several single-nucleotide polymorphisms, many derived from recombination events, and gene gain and loss events separated olive-infecting strains from coffee-infecting strains in this clade. The olive-specific variation suggests that this event was a host jump with genetic isolation between coffee- and olive-infecting X. fastidiosa populations. Next, we investigated the hypothesis of genetic convergence in the host shift from coffee to olive in both populations (Brazil and Italy). Each clade had multiple mutations and gene gain and loss events unique to olive, yet no overlap between clades. Using a genome-wide association study technique, we did not find any plausible candidates for convergence. Overall, this work suggests that the two populations adapted to infect olive trees through independent genetic solutions.     

Are Brazil nut populations threatened by fruit harvest?

Harvest of Brazil nuts from the large, iconic tree Bertholletia excelsa generates substantial income for smallholders, providing a strong incentive to conserve the mature forests where it grows. Although much previous work has focused on the impact of nut harvest on new seedling recruits into B. excelsa populations, the connection between harvest rates and long‐term population stability is still unclear. Moreover, there is additional uncertainty for Brazil nut management in terms of population response to climate change and other anthropogenic influences. We drew on 14 years of research in two sites in Acre, Brazil with different B. excelsa nut harvest intensities (39% and 81%), to produce stochastic and deterministic matrix population models which incorporated parameter uncertainty in vital rates. Adult abundance was projected to remain close to the current observed abundance or higher through the next 50 years. Elasticity analyses revealed that the asymptotic population growth rate (λ) was most sensitive to stasis vital rates in sapling, juvenile, and adult stages. Deterministic transition matrices calculated using diameter growth rates dependent on rainfall yielded average λ values around 1.0 under extreme high, extreme low, and average annual rainfall. While sustained high rates of Brazil nut harvest and climate change could potentially negatively impact B. excelsa populations, changes in human use of the forested landscape are more immediate concern. To reduce the risk of population decline, smallholders and managers of B. excelsa rich forests should focus on conservation of pre‐mature and mature individuals.     

The cashew nut, Anacardium occidentale (Anacardiaceae), and its perennial association with ants: extrafloral nectary location and the potential for ant defense

Cashew nut trees are consistently ant-visited throughout the year, with the ants attracted to a large number of extrafloral nectaries on the leaves, inflorescences, flowers, and developing nuts. The commercial production of cashew nut, for example, in India, Brazil, and east Africa, consistently applies pesticides, especially insecticides, in large monoculture plantings. Each year prophylactic spraying begins with the first flush of new leaves, continues through flowering, ending at about mid-nut development. We surveyed for ant diversity in sprayed and unsprayed cashew monocultures of various sizes and ages in Sri Lanka, India, and Malaysia to document the ant-cashew relationship and to explore the potential of ants replacing chemical pesticides in insect control. Using for-profit, commercial-size plantations as examples, we present information that cashew has a strong potential for arthropod-dependent protection from pests and suggest important habitat considerations for encouraging ants within cashew plantings.     

Geographic variation in nut size of<Emphasis Type="Italic"> Castanopsis</Emphasis> species in Japan

The environmental conditions affecting the geographic variation in nut size of the Castanopsis species in Japan were examined. The mother trees having a relatively large nut tended to dominate in the geographically marginal area of the distribution range in Japan, i.e. the Japan Sea, Kanto, and Ryukyu areas, whereas in the central area, i.e. the Pacific area, mother trees having a relatively small nut occurred. We attempted an adaptive explanation, proposing that mother trees with large nuts have higher inclusive fitness than those with small nuts in unfavorable habitats. The Japan Sea area features large amounts of snow fall and low temperatures. The Ryukyu area is insular and is characterized by high temperatures. Within the Pacific area, mother trees with relatively large nuts were abundant at both higher and lower parts of the altitudinal range. We infer that environmental conditions in marginal areas, in terms of both horizontal and vertical distribution, favor mother trees having large nuts. However, in the marginal Kanto area, the cause of the absence of mother trees having relatively small nuts was independent of the environmental conditions. The geographic variation in nut size of Castanopsis species is not always explained by environmental factors.     

Genetic diversity of superior Persian walnut genotypes in Azadshahr,Iran

Persian walnut (Juglans regia L.) is known to have originated in central and eastern Asia. Remnants of these wild populations can still be found in the Hyrcanian forest in north-eastern Iran. In this study, 102 individual walnut trees from four geographic populations in the Azadshahr province (Vamenan, Kashidar, Rudbar and Saidabad) were sampled. We characterized individual trees using 28 standard morphological traits. The range of traits varied widely for some economically important characteristics including nut weight (6.1–19.79 g), kernel weight (2.9–9.4 g), and kernel fill percentage (26.51–60.34%). After morphological evaluation, 39 superior individuals based on nut quality and kernel fill percentage were selected for further genetic analysis. Individual superior trees were genotyped using 10 simple sequence repeat markers (SSR) and genetic diversity. Number of alleles per locus ranged from 3 (WGA005) to 12 (WGA054). Clustering analysis of 10 SSR loci divided the genotypes into three main groups. PCoA analysis clearly sorted genotypes into one of four distinctive groups which aligned with the cluster analysis. All analyses showed that individuals from Saidabad were genetically distinct. Likewise, results indicated that the high level of genetic diversity in Azadshahr region walnuts may provide a diverse source for superior walnuts in walnut breeding programs.     

Genetics of Brazil nut (Bertholletia excelsa Humb. & Bonpl.: Lecythidaceae)

Summary We provide an estimate of genetic variation within and between two populations of Bertholletia excelsa (Brazil nut), a large canopy tree found in the rain forests of South America. Average heterozygosity is 0.190, and 54.3% of the sampled loci are polymorphic. The population structure deviates significantly from Hardy-Weinberg expectations for Fest2 and Pgm2 (F =0.405 and 0.443, respectively) in one population, and highly significantly (F=-0.341) for Gdh in the other population. Although allele frequencies of the two populations differ significantly for Aat2, Est5, Mdh1, and Mdh2B, Nei's coefficient of gene differentiation (G_st) indicates that the between-population component (D_st) of genic diversity represents only 3.75% of the size of the within-population component (H_s). The implications of these findings in terms of conservation genetics are that much of the genetic diversity of this species may be preserved within one or a few populations. However, such populations must be very large because it appears that the large amount of genetic variation in Brazil nut populations is maintained by extensive gene flow and bonds of mating over a large area. The genetic architecture of Bertholletia excelsa is similar to that expected for an extensively diploidized paleopolyploid species.     

Anthropogenic Landscape in Southeastern Amazonia: Contemporary Impacts of Low-Intensity Harvesting and Dispersal of Brazil Nuts by the Kayapó Indigenous People

Brazil nut, the Bertholletia excelsa seed, is one of the most important non-timber forest products in the Amazon Forest and the livelihoods of thousands of traditional Amazonian families depend on its commercialization. B. excelsa has been frequently cited as an indicator of anthropogenic forests and there is strong evidence that past human management has significantly contributed to its present distribution across the Amazon, suggesting that low levels of harvesting may play a positive role in B. excelsa recruitment. Here, we evaluate the effects of Brazil nut harvesting by the Kayapó Indigenous people of southeastern Amazonia on seedling recruitment in 20 B. excelsa groves subjected to different harvesting intensities, and investigated if management by harvesters influences patterns of B. excelsa distribution. The number of years of low-intensity Brazil nut harvesting by the Kayapó over the past two decades was positively related to B. excelsa seedling density in groves. One of the mechanisms behind the higher seedling density in harvested sites seems to be seed dispersal by harvesters along trails. The Kayapó also intentionally plant B. excelsa seeds and seedlings across their territories. Our results show not only that low-intensity Brazil nut harvesting by the Kayapó people does not reduce recruitment of seedlings, but that harvesting and/or associated activities conducted by traditional harvesters may benefit B. excelsa beyond grove borders. Our study supports the hypothesis that B. excelsa dispersal throughout the Amazon was, at least in part, influenced by indigenous groups, and strongly suggests that current human management contributes to the maintenance and formation of B. excelsa groves. We suggest that changes in Brazil nut management practices by traditional people to prevent harvesting impacts may be unnecessary and even counterproductive in many areas, and should be carefully evaluated before implementation.     

Competition for dead trees between humans and aye-ayes (<Emphasis Type="Italic">Daubentonia madagascariensis</Emphasis>) in central eastern Madagascar

The destruction and degradation of forest habitats are major threats to the sustainability of lemur populations in Madagascar. Madagascan landscapes often contain forest fragments that represent refuges for native fauna, while also being used for firewood and timber by local human populations. As undisturbed forest becomes increasingly scarce, understanding resource competition between humans and wildlife in disturbed habitats will be increasingly important. We tested the hypothesis that Malagasy and aye-ayes (Daubentonia madagascariensis) compete for the limited number of dead trees in rainforest fragments at Tsinjoarivo, Madagascar. We surveyed 2.16 ha within five fragments (range 5–228 ha) surrounding human settlements to quantify the density of dead trees and traces of both human and aye-aye activity. Neither aye-aye nor human traces were distributed according to the availability of particular trees species, and aye-ayes and Malagasy apparently preferred several different species. Although overlap was recorded in tree species used, human use tended to be positively correlated with a species’ desirability as firewood, while a negative relationship was seen for aye-ayes. Both consumers used trees of similar diameter at breast height, but those used by aye-ayes tended to be older, suggesting that human use might precede usefulness for aye-ayes. Finally, the density of dead trees and aye-aye traces were highest in smaller fragments, but human traces did not vary across fragment size. Although further study is needed to better quantify the aye-aye diet in this region, these data suggest that aye-ayes and local people compete for dead trees, and this competition could constitute a pressure on aye-aye populations.     

Towards better use of Indonesian peatlands with paludiculture and low-drainage food crops

The current drainage-based peatland management systems in Indonesia result in high fire risks, soil subsidence and CO₂ emissions. This study aims to assess different alternatives of peatland crops in order to help prevent further degradation of peatlands in Indonesia. We focus on tropical peatland crops that provide food and that are of particular interest to smallholders. We compare various peatland food crops that are commonly grown with no drainage (paludiculture) or drainage below 50 cm in our study area, Central Kalimantan, Indonesia in terms of sustainability, profitability, scalability of the market and acceptability to farmers. Our results show that sago (Metroxylon sagu), banana (Musa paradisiaca) and pineapple (Ananas comosus) followed by water spinach/kangkong (Ipomoea aquatica), kelakai/edible fern (Stenochlaena palustris), illipe nut/tengkawang (Shorea spp.), dragon fruit (Hylocereus undatus), mangosteen (Garcinia mangostana) and sweet melon/melon (Cucumis melo) are the best options based on the aggregated scores for these criteria (but precaution should be taken when planting crops that require low drainage). Sago palm and illipe nut have the highest scores for both sustainability and scalability of market, whereas banana, pineapple and sweet melon have the highest scores in term of the scalability of market and acceptability to farmers. We also address key opportunities and bottlenecks for the development of paludiculture food crops and present recommendations for the implementation of paludiculture in Indonesian peatlands.

     

Distribution and population structure of four Central Amazonian high-várzea timber species

Amazonian white-water (várzea) floodplains harbor many commercially important timber species which in Brazil are harvested following regulations of the Federal Environmental Agency (IBAMA). Although it is well-known that tree physiology, growth, and species distribution of Amazonian floodplain trees is linked to the heights and durations of the periodical inundations, information about timber stocks and population dynamics is lacking for most tree species. We investigated timber stocks and the population structure of four intensely logged tree species in a western Brazilian várzea forest on an area totaling 7.5 ha. Spatial distribution was investigated in all trees as a function of inundation height and duration and the distance to the river channel, and additionally for saplings (trees <10 cm diameter at breast height––DBH) as a function of the relative photosynthetically active radiation (rPAR). The diameter-class distribution in Hura crepitans and Ocotea cymbarum indicated that populations are subject to density variations that possibly are traced to small-scale flood variability. In all species, saplings concentrated at higher topographic elevations than the mature tree populations, which suggest that the physical ‘escape’ from a flooded environment is an important acclimation to flooding. While Ocotea cymbarum and Guarea guidonia were high-density wood species characterized by random dispersion and a pronounced shade-tolerance, Hura crepitans and Sterculia apetala presented lower wood density, aggregated dispersion, and were more light-demanding. All species presented exploitable stems according to the current harvest regulations, with elevated abundances in comparison to other Amazonian forest types. However, stem densities are below the harvest rates indicating that the harvest regulations are not sustainable. We recommend that the forest management in várzea forests should include specific establishment rates of timber species in dependence of the peculiar site conditions to achieve sustainability.     

Association of the "IUCN vulnerable" spiny rat Clyomys bishopi (Rodentia: Echimyidae) with palm trees and armadillo burrows in southeastern Brazil

The globally vulnerable Clyomys bishopi, a semi-fossorial and colonial rodent, is apparently limited to cerrado (savannah-like vegetation) physiognomies in S?o Paulo State, Brazil. The aim of the study was to verify whether the presence of C. bishopi is associated to the occurrence of palm trees (Attalea gearensis, Syagrus loefgrenii) and armadillo burrows. Thirty six quadrats were placed in different physiognomies of cerrado vegetation at Itirapina Ecological Station, southeastern Brazil to survey the number of C. bishopi burrows of individuals of palm trees and burrows of armadillos. There was a strong dependence and association between the number of C. bishopi burrows and all measured variables (Contingency tables and Spearman rank correlations). It is suggested that this rodent can be found in great numbers where palm trees are abundant. The use of armadillo burrows possibly makes the movement of the rodents easier inside their own galleries.     

“Made in Brazil”: Human Dispersal of the Brazil Nut (<Emphasis Type="Italic">Bertholletia excelsa</Emphasis>, Lecythidaceae) in Ancient Amazonia<Superscript>1</Superscript>

“Made in Brazil”: Human Dispersal of the Brazil Nut ( Bertholletia excelsa , Lecythidaceae) in Ancient Amazonia. The Brazil nut, Bertholletia excelsa, is a colossal tree of terra firme forest whose seeds represent the most important non-timber forest product in Amazonia. Its peculiarly inefficient dispersal strategy and discontinuous distribution have led some to hypothesize anthropogenic origins, but evidence to date has been inconclusive. Here we present results of a multidisciplinary study addressing this question. A review of the geographic distribution of B. excelsa and comparison with that of similar Lecythis species suggest a number of anomalies that are consistent with a recent and wide colonization of Bertholletia. Published studies and field observations indicate that anthropogenic disturbance facilitates Brazil nut regeneration. Recent genetic studies showing no sequence diversity and no geographical structuring of within-population variability support a rapid and recent irradiation from an ancestral population. Historical linguistic analysis of indigenous terms for Brazil nut suggests a northern/eastern Amazonian origin for Bertholletia, with a concomitant spread of Brazil nut distribution or cultivation to the south and west. Such an expansion would have been particularly facilitated by the emergence of intensive bitter manioc cultivation and networks of interethnic trade beginning in the first millennium C.E. Together, ecological, phytogeographic, genetic, linguistic, and archeological data reinforce the hypothesis that ancient Amazonian peoples played a role in establishing this emblematic and economically important rainforest landscape.     

Can current native tree seedling production and infrastructure meet an increasing forest restoration demand in Brazil?

Recent global commitments have placed forest and landscape restoration at the forefront of countries' efforts to recover ecosystem services, conserve biodiversity, and mitigate the effects of climate change. However, it needs to be asked if current native tree seedling supply meets an increase in demand for forest restoration? This study assessed the current configuration, distribution, and production capacity of forest nurseries producing native trees in Brazil. Brazil provides an interesting example of how global agreements aligned with national policies can lead to the proliferation of native seedling nurseries, and the challenges faced to restore species‐rich native forest ecosystems. We found that the nurseries in the Atlantic Forest region can still meet an increase in demand—both in terms of seedling quantity and diversity—because most of their production capacity is not currently used. However, not all Brazilian biomes have sufficient nurseries to meet restoration demands, thus there is a risk of using native species from a few biogeographical regions in a much spatially wider and ecologically diverse area. In addition, lack of seed supply and qualified labor can hamper the growth of the market. Barriers to seed supply may also lead to low levels of genetic variability and floristic representation in the populations and ecosystems to be restored. We conclude that restoration of high‐diversity forest ecosystems requires policies and supportive programs, with emphasis on private nurseries, to guarantee adequate supply of native tree seedlings and provide the necessary incentives to develop the emergent economy of forest restoration.