Justification
This tree is native to Argentina, Bolivia, Brazil, Paraguay and Peru. Despite the wide range of the species, it has a naturally low population density. This density has also declined due to a variety of anthropogenic activities. The species produces a valuable timber, for which it has been over extracted for several centuries. Extraction continues, but in some localities the species is banned from logging. Additional threats to the species are from predation of seeds and seedlings, and harvest of bark for medicinal use. The species is found in several threatened habitats across its range, including the sub-Andean piedmont forest and in the Brazilian Caatinga and Cerrado phytogeographical domains. In each of these habitats, over 50% of the natural vegetation has been lost. Habitat decline is caused by agricultural expansion, development of roads and settlements. Due to the extent of habitat loss and the added pressure on the species from timber harvest, it is assessed as Endangered, with a suspected population decline of between 50 and 80% over three generations.
Geographic Range Information
This species is native to Argentina, Bolivia, Brazil, Paraguay and Peru. In Brazil the species is present in Tocantins, Alagoas, Bahia, Ceará, Paraíba, Pernambuco, Piauí, Rio Grande do Norte, Goiás, Mato Grosso do Sul, Espírito Santo, Minas Gerais, Rio de Janeiro and São Paulo states (Flora do Brasil 2022). In Bolivia, the species is thought to only remain in 10 localities (MMAyA 2020). In Argentina the species has a restricted range, within the Sub-Andean Piedmont Forest in Salta and Jujuy (Politi et al. 2015). The extent of occurrence for the species is over 7 million square kilometres.
Population Information
It was reported in 1998 that 'all stands of large trees are being or have been destroyed', however the tree can still be found and there is no numerical evidence to support this statement. However, it is still likely that the species has experienced severe population decline given that it is a valuable timber species. In general, the population of the species is poorly known across the geographic range (Politi et al. 2014).
In Bolivia, the species has experienced rapid reduction due to high exploitation and constant degradation of habitat (MMAyA 2020). All localities in Bolivia have a low species density (MMAyA 2022) and the species has low abundance in production areas. There is also a lack of regeneration and recruitment of seedlings, particularly after logging events. There is also predation of fruit, further reducing recovery. In Bolivia, the volumes of use have had a reduction of approximately 53% in a period of 13 years from 1992 to 2005 (s.f. 2007) (MMAyA 2022). Decline in Bolivia is also driven by human land use change to pasture and settlement, and an increased occurrence of fire.
In Argentina, the species has a 'low population density' but may also have been rare historically (Politi et al. 2014). The species is restricted to two provinces, Salta and Jujuy. The first employs a minimum cutting diameter of 60 cm diameter at breast height (DBH) forest management, while in the second the logging of Amburana cearensis has been banned since 1972 (Politi et al. 2014). This legislation is reflective of the extent of decline the species has experienced due to over extraction in the first half of the 20th century. Currently, the species is described to have 'depleted stocks' (Názaro et al. 2021). The occurrence of the species in the sub-Andean piedmont forest, one of the most threatened habitats in Argentina, also causes decline due to land use conversion and general logging in lowland areas (Politi et al. 2014). It is suspected that less than 37% of the piedmont forest remains (Politi et al. 2014). The species is found to have a bell shaped distribution in size class - with mid-diameter classes being the most frequent (Politi et al. 2014, Názaro et al. 2021). This has contributed to a limited regeneration capacity for the species (Názaro et al. 2021).
In Brazil, the species also experiences decline as it occupies the Caatinga which has suffered mass conversion and disturbance from shifting agriculture and other practices (Leite 2004). The species is still found in the mosaic landscape as individual relic trees (Leite 2004). It is thought that less than 50% of the original Caatinga vegetation remains (Silva et al. 2017, Antongiovanni et al. 2020). The species is also present in the Cerrado, another threatened habitat in Brazil. The occurrence of the species here is also likely to contribute to decline. It is suspected that less than 40% of the original Cerrado habitat area remains (Durigan et al. 2007). Decline is also caused due to economic demand for the species, due to the valuable timber and medical substance the species provides (Alvim et al. 2020).
Given the threats to the species across the range, both to stands of trees and the habitat of the species, it is suspected that population decline over the last three generations is at least 50%. In most habitats the species occupies, over 60% of the natural habitat has been lost, coupled with the targeted extraction of the species for timber it is likely that population decline for the species falls between 50 and 80%.
Habitat and Ecology Information
This species can reach to 25 m in height. The species grows in lowland dry forest, including the Brazilian Cerrado and Caatinga (Leite 2004) and the sub-Andean piedmont forest in Argentina. It grows at elevations from 20 to 800 m in the Brazilian Caatinga (Souza et al. 2021). The species bears fruit every 3–4 years during September and October in Argentina (Politi et al. 2013), in Paraguay it is between October and December (Leite 2004). The species is an important source of late season nectar for bees. It has a growth rate of 0.89cm year -1.
Threats Information
The species suffers from multiple threats at the habitat and species level.
At the species level, the species has been over-extracted for timber. This has caused historical population decline. Although this is now better managed in some range states, there is a knock on affect to the regeneration of the species observed in the size-class structure of remnant subpopulations (Názaro et al. 2021). Regeneration is also limited by seed predation in the Caatinga (Almedia et al. 2017) and in Bolivia (MMAyA 2020). Individual trees and stands may also be threatened by bark removal, which is used for medicinal purposes (Almedia et al. 2017).
At the habitat level, the species is threatened by habitat conversion across the geographic range. The drivers for this are shifting and industrial agriculture, for crops such as soy, for pasture and plantations for paper and pulp production. There is also a threat from urbanization and development, including construction and expansion of new settlements and roads (MMAyA 2020). In Bolivia there is also an increased occurrence of fire (MMAyA 2020).
Use and Trade Information
This species has multiple uses. It produces a valuable timber, which is used in construction, for window frames, carpentry, crafting and veneer (Leite 2004). The species is used in agroforestry systems and as an ornamental (Pimentel et al. 2015). Different parts of this plant, such as leaves, stems and seeds, are widely used in folk medicine and have been confirmed to have multiple medicinal applications (Alvim et al. 2020). Essential oils may also be distracted and used in perfumery (Leite 2004). The species is also important to provide nectar for bees in the dry season, and consequently for honey makers (Silvia et al. 2014).
Conservation Actions Information
Small trees grow around granite outcrops where they are safe from commercial exploitation. The species is also found in protected areas and ex situ collections, but these should be monitored to ensure they are protecting adequate diversity. It is suggested in Politi et al. (2014) that more of subpopulations in the piedmont need to be introduced to the protected area network, that there is reinforcement planting and assistance to natural regeneration, that it is ensured there is buy in from local stakeholders and that remnant individuals are protected. It is likely these recommendations would be useful across the range of the species. Additionally, action needs to be taken to reduce the threat to the species from trade.