Atmospheric 210Pb as a tracer for soil organic carbon transport in a coniferous forest

Abstract

Core soils and falling litter samples were collected in a Japanese cypress forest (Chamaecyparis obtusa) to determine the litter-fed ²¹⁰Pb_ex and organic carbon transfer from the forest canopy to soil and their subsequent distribution. Of the canopy residing ²¹⁰Pb_ex pool, litterfall annually transports 53% to the forest floor while it adds 117 g m⁻² per year of organic carbon to the forest soil, implying that litterfall dynamics can influence the distribution of ²¹⁰Pb_ex and soil organic carbon (SOC). ²¹⁰Pb_ex and SOC showed identical profile shapes and strong correlation in spatial as well as along the soil depth, indicating that both are affected by a similar process. Given the ubiquitous natural source of ²¹⁰Pb_ex, it is plausible to infer that radiolead can be a possible tracer to study the SOC redistribution at regional and global scales.