Grassland Vegetation-Soil-Enzyme Responses to Gold Mineralization Anomalies: Implications for Ecological Restoration and Net-Zero Ecosystem Management

Gold-mineralized grasslands may contain spatially variable gold (Au) and associated elements such as arsenic (As) and mercury (Hg). Ecological effects are difficult to attribute because natural mineralization, mining disturbance and other sources of metal contamination may overlap. This narrative review examines vegetation, soil geochemistry and microbial enzyme activity in grasslands and related metal-affected systems. The available studies are heterogeneous and often do not measure Au, vegetation, soil properties and enzyme activity together. Studies that do not measure Au are treated as contextual evidence, not direct evidence of Au-specific effects. Unsupported cross-site Au concentrations, pooled regolith statistics, universal particle-size or dispersion ranges, plant accumulation values and enzyme diagnostic thresholds have been removed. Enzyme activities are complementary indicators of soil biological functioning, not validated Au-specific diagnostics. Restoration evidence from other ecosystems can inform hypotheses but cannot establish universal restoration outcomes for naturally mineralized grasslands. Changes in enzyme activity or SOC alone do not demonstrate net-zero performance; assessment requires repeated SOC-stock measurements, plant carbon inputs, CO₂, CH₄ and N₂O fluxes, and consideration of restoration-related emissions. The review therefore presents a conceptual monitoring agenda and testable research priorities rather than a validated causal model or universal thresholds.