The forest, the cicadas and the holey fluxes: Periodical cicada impacts on soil respiration depends on tree mycorrhizal type

The emergence of billions of periodical cicadas affects plant and animal communities profoundly, yet little is known about cicada impacts on soil carbon fluxes. We investigated the effects of Brood X cicadas (Magicicada septendecim, M. cassinii and M. septendeculain) on soil CO₂ fluxes (R_S ) in three Indiana forests. We hypothesized R_S would be sensitive to emergence hole density, with the greatest effects occurring in soils with the lowest ambient fluxes. In support of our hypothesis, R_S increased with increasing hole density and greater effects were observed near AM-associating trees (which expressed lower ambient fluxes) than near EcM-associating trees. Additionally, R_S from emergence holes increased the temperature sensitivity (Q₁₀ ) of R_S by 13%, elevating the Q₁₀ of ecosystem respiration. Brood X cicadas increased annual R_S by ca. 2.5%, translating to an additional 717 Gg of CO₂ across forested areas. As such, periodical cicadas can have substantial effects on soil processes and biogeochemistry.