Mining Disturbance Is Associated with Differences in Medicinal Tree Diversity, Community Structure, and Biomass Carbon Stocks in the Peruvian Amazon

Alluvial gold mining can alter Amazonian tree communities, but its association with medicinal tree diversity, structure, and carbon stocks remains poorly documented. We compared four 1-ha forest plots in Boca Colorado, Madre de Dios, Peru: two with greater evidence of mining intervention and two less-impacted plots. All medicinal trees with DBH ≥ 10 cm were inventoried, and taxon richness, Hill diversity, rarefaction, floristic dissimilarity, dominance, structural attributes, and biomass carbon were evaluated. A total of 1344 individuals representing 203 taxa were recorded. Mean plot-level richness was higher in less-impacted forests than in impacted forests (135.5 vs. 95.5 taxa), as were diversity of orders q = 1 (79.9 vs. 48.1) and q = 2 (38.7 vs. 23.6). Richness therefore showed a scale-dependent pattern: less-impacted plots were richer individually, whereas impacted forests accumulated more taxa when plots were pooled (172 vs. 143), reflecting greater among-plot differentiation. Turnover accounted for 79.5% of Jaccard dissimilarity. Less-impacted forests also had 16.1% higher stem density and 47.1% higher total biomass carbon, with the carbon contrast supported by the hierarchical bootstrap analysis (p = 0.043). These findings indicate that mining intervention was associated with differences in abundance distribution, floristic composition, forest structure, and carbon stocks that were not captured by pooled richness alone.