Total soil respiration and soil microbial respiration declined with increasing acid addition rate for each month (Fig. 2a–b). In contrast, root respiration increased with acid addition for each month (Fig. 2c). After averaging the total soil CO2 efflux and its sources of three months into one, we also found that the total soil respiration and soil microbial respiration decreased with acid addition while root respiration increased with acid addition (Fig. 2d–f)