Brazil nut journey under future climate change in Amazon

shift their distribution above the maximum altitude of the mountain under the scenario from RCP2.6 to the year 2050. This displacement to areas of higher altitudes is also being recorded for animal species. Stream fish species of the genera Barbus and Leuciscus, it is predicted to colonize newly suit- able areas in stretches of higher elevation or to extend their ranges towards the poles [58–60]. [61] studying birds endemic to the mountains of eastern Brazil predicted that all species stud- ied in all scenarios (2050 and 2070) will experience a shift in their distributions to higher areas. A similar finding was also found for birds from high mountains in temperate and tropical regions, such as the Andes [62–64]. In many parts of its distribution range, B. excelsa occurs in an aggregated pattern, forming clusters known as ’manchales’, ’castanhais’ or ’reboleiras’, which are interspersed with vast areas of forest with very few or no trees. The scale of these clusters varies, and at the local level, the dispersion of B. excelsa is usually attributed to Dasyprocta species. At a regional and conti- nental level, it is attributed to humans acting as dispersal agents, with evidence of human activ- ity ranging from 12,000 to 20,000 years Before Present (BP) [21]. In a more recent scenario, it is known that the B. excelsa distribution across Central Amazo- nia changed drastically not only with regional climatic variability but also with major political and socioeconomic activities during post-colonial era (over 400 years ago)–the collapse of pre-

Columbian indigenous (e.g., Mura populations) led to the interruption of management prac- tices, affecting the B. excelsa as well [17]. In a future scenario where there is a reduction and/or absence of Dasyprocta species, B. excelsa will rely on human dispersion to colonize new areas suitable for its growth, as seen in the yellow areas in Fig 3. Moreover, future projections of climate change show that pollinators’ range may reduce drastically in the future, which might cause a spatial mismatch between B. excelsa and its community of pollinators [54]. In this sense, our finding aligns well with [21] results, especially for our SSP5-8.5 scenario result (Fig 3D), where the western portion of the Amazon might be suitable for B. excelsa colonization if there is human intervention. It is difficult to predict how B. excelsa will fare in the future climate along with human inter- vention. However, because of its importance for the bioeconomy, it is possible to infer that the species might be planted in more areas towards the Brazilian Western Amazon in the future. Brazil is the leading exporter of Brazil nuts with shells, holding a 47% share of its global market between 2017 and 2019. The global market for this product is relatively small (US$24 million/ year), and the main destinations for Brazil nuts with shells are Peru (38%) and Bolivia (16%). Both countries purchase Brazil nuts with shells as raw materials and use their superior indus- trial and commercial capacities to process and export them as Brazil nuts without shells, a

product with a unit price four times higher (US$9.1/kg without shell against US$2.2/kg with shell) and a total market almost 15 times larger (US$364 million) [65]. Brazil nuts not only play a key role in the ecology and nutrient cycling of the Amazon for- ests, but also have their importance for human subsistence since the settlement of the Amazon [66, 67]. In addition, Brazil nuts play an important role in carbon sequestration [68]. In this way, information on the best areas for human management practices, restoration potential, contributes to more efficient conservation efforts, maintenance of Brazil nut trees and the design of management strategies, given that the species is currently considered threatened by the Ministry of the Environment (Law No. 443/2014 MMA, 2014). Conclusions Our results indicate that there is a high risk of the extinction of the iconic species Bertholletia excelsa because of the effects of climate change by the end of the century. This risk can be PLOS ONE Effects of climate change on Brazil nut PLOS ONE | https://doi.org/10.1371/journal.pone.0312308 November 13, 2024 9 / 13