The Caatinga socioecological system
The Caatinga dry forest has high inter-and intra-annual rainfall variation, changing up to 1000% from one year to another in the same place (Andradeet al., 2017). The rainfall amount goes from 400 to 1500 mm per year across the biome, being considered the wettest seasonally dry forest in the world (Andrade et al., 2017). The vegetation is dominated by small-leaved, thorny trees and several species of succulents (Queiroz et al., 2017). Water for irrigation comes mostly from rivers and wells, but as almost all rivers are intermittent, the largest share of the agriculture is rain-fed or relies on rainfall accumulated in the wetter valleys (Sampaioet al., 2017). Water for consumption comes from diverse sources (e.g. wells, cisterns, water trucks), but they are not necessarily of adequate quality, which can impact local food security (Sena et al., 2018). The Caatinga has very diverse soil conditions, but most of the areas present low fertility which reduces the agricultural aptitude (Sampaio et al., 2017). Combined, those environmental characteristics contribute to the low productivity of the agricultural system and to poor socioeconomic conditions of most farmers (Tabarelli et al., 2017).
The set of municipalities comprising the Caatinga have the lowest levels of human development in Brazil (Silva et al., 2017). Most of the municipalities are considered rural (IBGE, 2017), where most farmers produce maize and beans associated with small-scale animal production for their subsistence (Sampaio et al., 2017). Goat production is the main strategy that poor rural farmers use worldwide in arid and semiarid regions (Caatinga included) especially during long droughts because of their tolerance to such climatic conditions and their ability to feed on natural vegetation (Devendra, 1999). Bovine production is mostly developed in a pasture with exotic grasses; however, only capitalised farmers normally engage in cattle production (Sampaio et al., 2017). Furthermore, the Caatinga is the most densely populated dry forest in the world with millions of people living in rural communities highly dependent on forest products (Albuquerque et al., 2017). Although the Caatinga still has intermediate levels of forest vegetation cover, the forest fragments are not evenly distributed across the biome (Antongiovanniet al., 2018) and have high levels of chronic anthropogenic disturbance linked to the historical use of native vegetation by local people (Antongiovanniet al., 2020).