RESTORATION OF DEGRADED RIPARIAN ECOSYSTEMS POST-TIN MINING IN THE CENTRAL AMAZON
Ecosystems; Environmental Recovery; Monitoring; Ecological Indicators
Riparian forests are defined as ecotones between terrestrial and aquatic environments, characterized by high biological productivity and ecological diversity. However, due to anthropogenic activities like mining, these ecosystems have been continuously degraded. Seedling planting is the most recommended method for areas where soil degradation has eliminated natural propagule sources. This study aimed to evaluate vegetation dynamics and ecological diversity in riparian ecosystems undergoing active restoration after tin mining in the Amazonas state, Central Amazon. Eight riparian forests of varying planting ages were evaluated, namely: 10 years (RF_10LA), 9 years (RF_9BR and RF_9PA), 8 years (RF_8MI and RF_8PI), 7 years (RF_7NO and RF_7JA), and ≤ 2.5 years (RF_2.5MA). The vegetation monitoring was carried out semiannually starting in July 2021, conducted within the plots, where each planted individual was measured for total height (Ht) and diameter at breast height (DBH). Permanent plots (30 m × 30 m) were allocated in each forest, with the number of units varying based on the total area size. Results demonstrated that active restoration effectively contributed to ecosystem recovery, promoting a gradual return of floristic composition over seven biannual measurements. Two groups formed based on species composition similarity in the streams: Group 1 (RF_2.5MA, RF_9BR, RF_9PA) and Group 2 (RF_10LA, RF_7JA, RF_8PI, RF_7NO, RF_8MI). Pioneer species showed the highest importance values, with Senna alata (L.) Roxb., V. guianensis, Bixa orellana L., and Trema micrantha (L.) Blume dominating the youngest ecosystem (RF_2.5MA). Most species were trees and shrubs (46% each), with only 1% being palms. Clitoria fairchildiana R. A. Howard and Adenanthera pavonina L. exhibited the greatest diameter and height increments compared to other species. This study underscores the importance of continuous monitoring to ensure the success of riparian forest restoration impacted by tin mining, promoting ecological benefits sustainably.