Carbon sequestration induced by enhanced silicate rock weathering in a temperate larch plantation in Northeastern China

Abstract

Enhanced rock weathering (ERW) is a promising strategy for sequestering carbon (C) via removing atmospheric CO₂ as bicarbonate or carbonate. Previous in-situ field experiments concentrated on inorganic C sequestration by ERW, while paying little attention to the response at an ecosystem scale. In forest ecosystems, soil organic C (SOC) and tree growth represent major components of ecosystem carbon storage, and their responses to ERW could contribute to additional carbon sequestration. In this study, we applied wollastonite powder (0, 5, and 10 t ha⁻¹) to a larch plantation in Northeast China and monitored soil CO₂ flux, soil C dynamics, and tree growth. Our results showed that wollastonite addition reduced soil CO₂ fluxes by 16.5 % and 15.4 % in the first year at dosages of 5 and 10 t ha⁻¹, respectively, likely due to enhanced SOC stability and the geochemical effects of wollastonite weathering. In the second year, soil CO₂ fluxes increased by 4.1 % and 5.1 % relative to the control, which can be attributed to stimulated root respiration and accelerated SOC decomposition in the Oa+e horizon following wollastonite application. Tree biomass showed an increasing trend (p > 0.05), suggesting a potential contribution of vegetation growth to ecosystem C sequestration. These findings highlight that both soil C dynamics and plant biomass responses should be considered when evaluating the C sequestration potential of ERW in forest ecosystems.