Data from: Limited biomass recovery from gold mining in Amazonian forests

Gold mining has rapidly increased across the Amazon Basin in recent years,
especially in the Guiana shield, where it is responsible for >90%
of total deforestation. However, the ability of forests to recover from
gold mining activities remains largely unquantified.  Forest
inventory plots were installed on recently abandoned mines in two major
mining regions in Guyana, and re-censused 18 months later, to provide the
first ground-based quantification of gold mining impacts on Amazon forest
biomass recovery.  We found that woody biomass recovery rates on
abandoned mining pits and tailing ponds are amongst the lowest ever
recorded for tropical forests, with close to no woody biomass
recovery after 3-4 years.  On the overburden sites (i.e. areas
not mined but where excavated soil is deposited), however, aboveground
biomass recovery rates (0.4 - 3.5 Mg ha-1 yr-1) were within the
range of those recorded in other secondary forests across the Neotropics
following abandonment of pastures and agricultural lands.  Our
results suggest that forest recovery is more strongly limited by severe
mining-induced depletion of soil nutrients, especially nitrogen, than by
mercury contamination, due to slowing of growth in nutrient-stripped
soils.  We estimate that the slow recovery rates in mining pits
and ponds currently reduce carbon sequestration across Amazonian secondary
forests by ~21,000 t C yr-1, compared to the carbon that would have
accumulated following more traditional land uses such as agriculture or
pasture.  Synthesis and applications. To achieve large-scale
restoration targets, Guyana and other Amazonian countries will be
challenged to remediate previously mined lands. The recovery process is
highly dependent on nitrogen availability rather than mercury
contamination, affecting woody biomass regrowth. The significant recovery
in overburden zones indicates that one potential active remediation
strategy to promote biomass recovery may be to back-fill mining pits and
ponds with excavated soil.