Natural revegetation of areas impacted by gold mining in the tropical rain forest of Chocó, Colombia

Abstract

Introduction: Open pit gold mining causes drastic impacts on natural forests in tropical regions of high biodi-versity, and the efficacy of “revegetation”, a process of replanting and rebuilding the soil, is still poorly studied. Objective: To evaluate the effect of successional time, and distance to the reference forest, on the biological structure and species composition of revegetated gold mines. Methods: We inventoried the adjacent forest and abandoned gold mines in the tropical rain forest of Chocó, Colombia. The mines had 6, 10, 15, 19 and 24 years of natural succession. In each scenario, we set four 2 × 50 m plots: two 50 m and two 100 m from the forest-mine edge (ecotone). Results: We identified 300 plant species (193 genera, 75 families). The richness, diversity and evenness changed little with successional time in the mines but reached higher values in the forest. The species composition was similar between the mines with different successional times but differed widely from the forest (only 7 % similarity). The substrate quality and reproductive strategies of herbaceous plants (mainly Cyperaceae and Melastomataceae) and trees (Cespedesia spathulata and Miconia reducens) that grow spontaneously in the mines, play an important role on the early natural revegetation. Conclusions: The 24 years of natural succession have been insufficient to reach a community of a complexity similar to that of the forest, and distance from the ecotone has no significant effect; however, the substrate quality and reproductive strategies of herbaceous plants are important in the early stages of mine recovery in the Chocó.