**1. Introduction**

Brazil nut (*Bertholletia excelsa* Bonpl.) holds a key role in socio-bioeconomies [1, 2] providing vital economic inputs to local, national, and global markets during different seasons and bringing benefits to tens of thousands of small-scale producers [3] who live under a diversified economic portfolio [4]. It is also a source of food consumed in various forms, including fresh, roasted, or pressed for milk-like extract [5] within the Amazon, and outside (e.g., USA, China). Brazil is one of the leading

producers of Brazil nut harvesting 33,406 metric tons in 2021 [6]. *B. excelsa* is a monotypic genus of Lecythidaceae, a pantropical botanic family. These trees can reach heights of up to 60 meters and diameters of 5 meters, often occupying upland moist forest (non-flooded) and transitional zones between Amazon forests and Cerrado savannas, with some trees reaching up to 1000 years old [1, 5].

Human influences have contributed to shaping the geographic distribution and abundance of Brazil nuts in the Amazon, following the movement of Indigenous peoples across the Amazon for thousands of years by mean of area expansion and shifting cultivation activities [5, 7, 8]. Today the Brazil Nut is one of the 20 superdominant trees of the Amazon contributing beyond food security to the carbon cycle of the forest [9, 10]. The economy of the Brazil Nut in the Amazon is a forest-based extractive activity [6]. Brazil Nut trees form biodiverse forests gathered and traded by traditional communities, including extractivists, Indigenous groups, and African descendents (quilombola) [11–13]. This dynamic collaboration yields most of the Brazil nuts, creating a dual impact of income generation and biodiversity conservation [13, 14], impacting positively local people's livelihoods [15]. Brazil nut management may account for >40% of the annual extractivist family income [12].

The flowering phase is most pronounced during the driest months corresponding to the period of longer photoperiods. The mutualistic interactions between Brazil nut and their pollinators have significant implications for fruit production [16]. Fruiting occurs during the early rainy season (e.g., SON). The maturation process that lasts about 14 months indicates that the environmental conditions and biological interactions that occurred in the previous year can impact Brazil nut productivity in the following year [17]. Research conducted by Maués in 2002 revealed that precipitation, temperature, relative humidity, and photoperiod play a role in shaping the phenology of *B. excelsa* [17]. Pastana et al. showed that in a forest-savanna transition in the eastern Brazilian Amazon, the 2015/2016 El Niño phenomenon, when temperatures of the ocean increased more than 2°C during the dry season, fruit production decreased by up to 97% in 2017 [18]. The temporal variability in Brazil nut productivity influenced by climate oscillations pose major social and economic impacts on such forest-based extractivist communities in the Amazon, in some cases increasing by a quarter the prices of nut production unit (from USD 10 in 2016 to USD 38 in 2017) [18].

While Brazil nuts have gained significant economic importance in terms of both form and production volume, deforestation and climate changes are major threats to forest resilience impacting mainly large trees, subjected to drier and warmer climate, such as the Brazil nut tree [19, 20]. However, because the reproductive success of Brazil nut is intrinsically linked to the interaction of climatic conditions, pollination dynamics and human activities, the limits of resilience to the increasing changes in forest climate are not fully understood. Recent study, for instance, indicates that climate change could impact positively *B. excelsa* but only when seedlings are irrigated pointing to the fact that water restriction in the dry season in the Amazon is a key limiting factor [21].

To observe how seed productivity of Brazil nut varies across time and assess the potential impact of climate on its productivity, we compared temporal patterns of nut production between 1990 and 2021 in the Brazilian Amazon and in different socioecological Amazon sub-regions. To assess the influence of the climate variability on seed productivity we took the mesoregion Baixo Amazonas, one of the regions of the Amazon with the highest historical productivity and socioeconomic importance for the Brazil nut national market. Understanding the influence of climate variability in productivity provides an indicator of ecosystem stability and resilience, guiding sustainability of forest management systems [12].

*Threats and Sustainability of Brazil Nut* (Bertholletia excelsa *Bonpl.*) *Pre-Industrialization... DOI: http://dx.doi.org/10.5772/intechopen.113715*
