The Madre de Dios region in southeastern Peru, known for its biological and cultural diversity, is threatened by alluvial gold mining, which has led to deforestation and ecosystem degradation. This article focuses on the nodulation capacity of symbiotic nitrogen-fixing bacteria in the plant Stylosanthes guianensis in areas degraded by alluvial gold mining in Madre de Dios. The objectives were to characterize bacterial strains, evaluate their nodulation capacity and their influence on plant growth in mining substrate. The results indicate that the inoculation of these bacteria had a positive impact on the development of S. guianensis, promoting growth and the formation of effective nodules in all test conditions. In addition, it was observed that the slow-growing strains in vitro had a more beneficial effect on plant growth than the fast-growing strains. These findings suggest that inoculation of nitrogen-fixing bacteria may be an effective strategy for the restoration of degraded areas, highlighting the importance of symbiosis between these bacteria and the plant in the recovery of degraded ecosystems, and raises the need for further research to better understand the species involved in biological nitrogen fixation and to determine the best inoculants to increase forage yields of S. guianensis.

Artisanal and Small-Scale Gold Mining (ASGM) significantly contribute to land degradation in the Amazon, carried out by individual miners or small enterprises with limited capital. This practice exerts increasing pressure on biodiversity-rich forests. Due to limited information on edaphic conditions crucial for the restoration of these degraded areas, we employed a soil evaluation method in representative sites of the Peruvian Amazon, including two native communities and one protected natural area. The categorization of ASGM degraded areas into Cultural Landscape Units (CLUs) was confirmed and validated. Sentinel-2 and UAV remote sensing revealed over 122,000 ha deforested since the 1980s. Surface and soil profile assessments identified extreme new soil conditions with low chemical and physical fertility, characterized by coarse texture and rock fragments, hindering revegetation, especially during prolonged drought seasons. These degraded soils were classified as Entisols and Technosols according to Soil Taxonomy and the World Reference Base, respectively. Over time, natural regeneration and plantations improved soil formation, aligning with recognized soil classification systems. Given the current management practices, restoration planning should prioritize selected shrub and tree species, considering soil amendments to initiate soil recovery. This approach aligns with self-sustained successional stages and contributes to the objectives of Land Degradation Neutrality (LDN), Appropriate Mitigation and Adaptation Actions (NAMAs), and Sustainable Development Goals (SDGs).

Alluvial gold mining in the Peruvian Amazon has become a key driver of land degradation and deforestation. In the Madre de Dios region, known as “the capital of the Peruvian biodiversity”, more than 95,750 ha of old growth forest were degraded in the las twenty years, at the rate of 6000 ha every year. In Fortuna Community, located in this region of the Peruvian Amazon, we classified soils of mine spoils and compared them with nearby soil profiles of undisturbed old growth forest, founding that both impacted and non-impacted soils are young soils classified as Fluvisols and Regosols according to the WRB system (2005) and Entisols according to Soil Taxonomy (2014). Soils of mine spoils have low plant cover, low fertility, strong acidity, low cation exchange capacity, and high content of rock fragments in impacted soils; so the impacts on soils are remarkable decreasing the fertility and soil productivity compared to non-impacted soils. However, impacted soils are being improved as time passes by natural regeneration, interaction between plants and animals, pluvial precipitation and flooding that improve soil characteristic like organic soil matter and cation exchange capacity, developing a new soil. In spite there is limited information about these soils in the Amazon, this research contributes to characterized certain impacted sites in order to support making decision on how to best reclaim, rehabilitate or restore these Amazon ecosystems.