Contribution of forests to the carbon sink via biologically-mediated silicate weathering: A case study of China

摘要

AbstractDuring silicate weathering, atmospheric carbon dioxide (CO2) is consumed and base cations are released from silicate minerals to form carbonate and bicarbonate ions, which are finally deposited as carbonate complexes. Continental silicate weathering constitutes a stable carbon sink that is an important influence on long-term climate change, as it sequesters atmospheric carbon dioxide at a million-year time scale. Traditionally, CO2sequestered through silicate weathering is estimated by measuring the flux of the base cations to watersheds. However, plants also absorb considerable amounts of base cations. Plant biomass is often removed from ecosystems during harvesting. The base cations are subsequently released after decomposition of the harvested plant materials, and thereby enhance CO2consumption related to weathering. Here, we analyze plant biomass storage-harvest fluxes (production and removal of biomass from forests) of base cations in forests across China to quantify the relative contribution of forest trees to the terrestrial weathering-related carbon sink. Our data suggest that the potential CO2consumption rate for biomass-related silicate weathering (from the combined action of with afforestation/reforestation, controlled harvesting and rock powder amendment) in Chinese forests is 7.9±4.1Tg CO2yr−1. This represents ~34% of the chemical weathering rate in China. Globally, forests may increase CO2sequestration through biologically-mediated silicate weathering by ~32%.Graphical abstractDisplay OmittedHighlights•Atmospheric CO2sequestration through weathering is a stable carbon sink.•Plants biologically enhance weathering-related CO2consumption.•Biomass-related silicate weathering in China may consume 7.9±4.1Tg CO2yr−1.•Forests may increase CO2sequestration through silicate weathering by ~32%.