Biogeochemical Si cycling in bamboo forests with evergreen broad-leaved forest and coniferous forest in a temperate climate

Abstract

Bamboo often invades areas of anthropogenic disturbance in Japan and is Silicon (Si) accumulator. Silicon plays important roles in the global C cycle through silicate weathering and Si fluxes delivered into the ocean as part of the global Si cycle. Terrestrial vegetation influences the global Si cycle. However, there appear to be no reports showing regional terrestrial biogeochemical Si budgets of bamboo forests in a temperate climate. Therefore, in a temperate climate, we established two study sites with two plots each, one plot at each site was selected in forestland that had been invaded and dominated by bamboo and a second at each site in an adjacent evergreen broad-leaved forest or coniferous forest. To better understand the characteristics of biogeochemical Si cycling in bamboo forests, we compared biogeochemical Si cycling in the bamboo forests and other types of forests. Annual Si fluxes by litterfall of the bamboo forests were higher than those of the adjacent other forests. In both sites, the annual Si uptakes were greater in the bamboo forests than in the other forests, and in one site the available Si pool in the soil was also greater in the bamboo forest. We concluded that in the bamboo forests, those amounts of surplus Si to other forests might have been supplied by mineral weathering after bamboo invasion. Therefore, bamboo forests may have characteristics which enhance mineral weathering and dissolved Si release into soil solution from minerals, resulting in greater uptake of Si and return of Si to the soil.