Ecosystem carbon stock loss after a mega earthquake

Earthquake-induced geohazards, in particular landslides and debris flows, have the ability to disturb large stocks of organic carbon. Even a slight change in these stocks of organic carbon could affect atmospheric CO2 concentrations. Yet, the fate of ecosystem carbon delivery caused by a mega-earthquake over a short timescale is not well understood. In this study, a methodology is proposed to study the impact of earthquake-triggered landslides and post-seismic debris flows on ecosystem carbon (C). Pairs-plots were established on undisturbed areas, coseismic landslides or debris flow in one of the most representative catchments, in the 2008 Wenchuan earthquake hit regions. Results showed that coseismic landslides greatly reduced vegetation C stock from 34.48 Mgha-1 to 6.85 Mgha-1 and soil C stock from 96.38 to 6.77 Mgha-1, thereby leading to 89.6% reduction for total ecosystem C stock. Similarly, debris flow deposit led to a reduction of 97.8% of ecosystem C stock. Overall, it is estimated that there was a loss of 0.118×106Mg C across the study area, indicating a large amount of carbon change after the mega-earthquake. This study has an important implication for the role of mega-earthquake on regional ecosystem C storage and fills our knowledge gaps of the impact of ecosystem C cycle along with earthquake-induced geohazard chains.