In mitigating CO2 emission in the reservoir riparian: The influences of land use and the dam-triggered flooding on soil respiration

摘要

Soil respiration (SR) has been found to be highly influenced by land use and soil water regimes. However, the relative contribution of farming and dam-triggered flooding in influencing the SR of the riparian zone is poorly understood. The objectives of this study were to investigate the effects of land use and dam-triggered flooding intensity on SR in the riparian zone along the Three Gorges Reservoir (TGR), China, and to identify the main factors shaping the SR. At the Wuyang Bay of the Pengxi River, a tributary of the Yangtze River in the TGR, a series of SR field examinations in different land-use types and along elevation gradients in the riparian zone were carried out from March to September in 2018. During the study period, by analyzing SR in 177 m (elevation above sea level, the same as follows) unflooded site (tJF), 173 m corn field (173C), 173 m paddy field (173 P), 168 m corn field (168C), 168 m paddy field (168 P), 168 m fallow grassland (168 F), 166 m fallow grassland (166 F), 163 m corn field (163C) and 163 m fallow grassland (163 F), significant differences in diurnal variations were found to be mainly affected by soil temperature (ST) at 10 cm depth, while seasonal variations were mainly regulated by ST and rainfall events (i.e. 10 cm depth soil water content). Importantly, croplands were found to contain higher soil organic carbon (SOC) but lower SR efflux and Q(10) values than those for non-cropping fields. The results imply that SR was strongly affected by land-use types rather than flooding intensity in the TGR riparian zone. Furthermore, this study highlights the significant impacts of tillage in stabilizing SOC and reducing SR efflux in the area that is highly influenced by hydrological regime shift. Finally, from the perspective of controlling the soil carbon dioxide emission, we suggest that local government should manage and guide farming activities in the riparian zone.