Mercury in soils impacted by alluvial gold mining in the Peruvian Amazon

Context: Gold mining is the most destructive activity in the natural forests of the Madre de Dios region in the southeastern Peruvian Amazon. Understanding the natural regeneration process of these degraded areas is necessary to develop forest restoration projects in such conditions.Aims: We aimed to evaluate forest recovery and identify the successional and structure patterns of vegetation governing natural regeneration over time.Methods: Structure, composition, richness, diversity, and successional status were evaluated in abandoned artisanal gold mine areas in Madre de Dios, southeastern Peru. Vegetation data were recorded in 61 plots of 250 m2 established in five sites varying from 1 to 19 years of abandonment. Vegetation in abandoned areas was compared with six undisturbed forests evaluated in previous inventories.Results: In the mining lands, tree density and basal area recovered quickly, while species richness and composition were slow. Forest recovery is an initial stage of transition from pioneer to early secondary species until at least 19 years after abandonment. The most abundant and frequent species were the fast-growing species Ochroma pyramidale and Cecropia engleriana. These species could be considered potential candidates to promote restoration plans. Pioneer species represented 63% of the number of species in plots of 1–4 years, 57% in plots of 5–7 years, and 50% in plots of 8–19 years. Early and late secondary species represented 34 and 16%, respectively, of the number of species in plots of 8–19 years. Abandoned mining and reference plots present less than 5% of species in common.Conclusion: Our results highlight a slow natural regeneration process in areas for up to 19 years after gold mining. Species from different successional statuses were identified as potential candidates for recovering vegetation in such areas. Our findings may have important implications for further research focusing on the ecological restoration in tropical forests severely degraded by gold mining.

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Anthropogenic Vegetation in the River Valley Amalat

BIO Web of Conferences ◽

10.1051/bioconf/20191600049 ◽

2019 ◽

Vol 16 ◽

pp. 00049

Author(s):

Marina Tsyrenova ◽

Evgenia Pyzhikova ◽

Elena Vasilyeva

Keyword(s):

Vegetation Cover ◽

Gold Mining ◽

Research Study ◽

Gold Deposits ◽

Open Pit ◽

Current State ◽

Disturbed Areas ◽

Alluvial Gold ◽

Anthropogenic Vegetation ◽

Mining Methods

The article presents the results of a research study of anthropogenic affects of gold mining on forest landscapes in Northern Transbaikalia, Russia and processes of natural reclamation of vegetation cover of the disturbed areas. The study area is located northwest of the Maliy Amalat River, which flows along the Vitim Plateau; in the floodplains of its two tributaries the Aunik River and the Bagdarin River. It is an area where a large number of alluvial gold deposits have been discovered. Some of these deposits are currently being developed, some have already been explored, and some have been abandoned. The authors consider the current state of vegetation cover in a key area of the Amalat River basin, near villages of Malovsky and Bagdarin. The problem of natural resources development and conservation is becoming extremely important for the area under study because open-pit gold mining methods that are used here drastically change the environment and affect water, land and forest resources.

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