**2.1 Study area**

The Amazon Forest is located in South America (**Figure 1A**). The forest region covers 6.3 million square kilometers, spanning Brazil, Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela. The human population in the region is estimated at 38 million inhabitants [26], with indications of 6 million

#### **Figure 1.**

*Study area. Data source: INPE [22], QGIS [23], IBGE [24, 25].*

people directly dependent on the forest for subsistence in the Brazilian Amazon [27]. The study area is located in Brazil (**Figure 1B**), occupying approximately 4.2 million square kilometers [24].

The study area was subdivided into mesoregions, which were analyzed in terms of Brazil nut production volume (**Figure 1C**). As defined by Brazilian Institute of Geography and Statistics [25], a mesoregion is a geographical delineation within a Federal Unit, shaped by the dimensions of social processes as a determining factor, natural conditions as a conditioning factor, and the network of communication and places as elements of spatial articulation. These dimensions collectively confer a regional identity to the mesoregion, a construction over time by the local society. In total, the study area consisted of 26 mesoregions, which together covered a total area of 4.7 million square kilometers (**Figure 1C**).

The study of interactions between seed production and climatic variables focuses specifically on the Baixo Amazonas mesoregion, located in the northwest of the state of Pará (**Figure 1D**). Baixo Amazonas is the most important mesoregion for Brazil nut production in the state of Pará's non-timber forest extraction [6]. The Baixo Amazonas mesoregion consists of 13 municipalities (county) that make up the territory: Alenquer, Almeirim, Belterra, Curuá, Mojuí dos Campos, Faro, Juruti, Monte Alegre, Óbidos, Oriximiná, Prainha, Santarém, and Terra Santa, with an estimated population of 785,000 inhabitants in 2022 [28]. The region covers an area of 340,000 square kilometers, roughly the size of Germany (357,000 square kilometers).
