Study on Carbon Flux of Littoral in XiangXi river During Water Discharge

Riparian ecosystems are an important transition zone between river ecosystem and the terrestrial ecosystems and play an important role in the global carbon cycle of terrestrial ecosystems. The study was carried out in littoral in XiangXi river, which was the larger tributary and nearest to the Three Gorges Dam. Gas exchange rates were measured to explore the main factors controlling the carbon flux of littoral in XiangXi river using chamber method during water discharge in 2011. The results showed that in the early of water discharge, net ecosystem exchange (NEE) of 165- 175 m a.s.l. was 2.17 ± 0.53 μmol m-2 s-1, which was markedly lower than that of over 175 m a.s.l. (-1.04 ± 0.62 μmol m- 2 s-1, P < 0.05). Total ecosystem respiration (TER) of 165-175 m a.s.l. was 3.21 ± 0.52 μmol m-2 s-1, which was little lower than that of over 175 m a.s.l. (3.79 ± 0.94 μmol m-2 s-1), but there was no statistically significant difference (P > 0.05). The study indicated that being experienced flooding, the lower areas in littoral of the main stream of Xiangxi river might be a weak carbon source due to lower vegetation cover, higher soil water content and different soil microbial in the early of water discharge.