Shift in functional plant groups under flooding impacted ecosystem C and N dynamics across riparian zones in the Three Gorges of China

Dandan Zhang; Jiao Feng; Fan Yang; Junjun Wu; Wei Jia; Xiaoli Cheng

doi:10.1016/j.scitotenv.2020.138302

Shift in functional plant groups under flooding impacted ecosystem C and N dynamics across riparian zones in the Three Gorges of China

Sci Total Environ. 2020 Jul 1:724:138302. doi: 10.1016/j.scitotenv.2020.138302. Epub 2020 Mar 30.

Authors

Dandan Zhang¹, Jiao Feng², Fan Yang³, Junjun Wu⁴, Wei Jia⁴, Xiaoli Cheng⁵

Affiliations

¹ Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences (CAS), Wuhan 430074, PR China; Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
² School of Resources and Environmental Science, Huazhong Agriculture University, Wuhan 430074, PR China.
³ School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China.
⁴ Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences (CAS), Wuhan 430074, PR China.
⁵ Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences (CAS), Wuhan 430074, PR China; School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, China. Electronic address: xlcheng@fudan.edu.cn.

PMID: 32247970
DOI: 10.1016/j.scitotenv.2020.138302

Abstract

Large water conservancy project can strongly alter the plant community composition, however, how these changes can potentially affect ecosystem carbon (C) and nitrogen (N) dynamics is not fully understood. Here, we investigated natural ¹³C and ¹⁵N abundance of C₃ and C₄ plants and soil in different fractions [labile C (LC) and N (LN), recalcitrant C (RC) and N (RN)]from 6 sites with two elevations (flooding zone, 145-175 m, area with revegetation due to flooding, N = 6); and unflooding zone, >175 m with original plant as a control, N = 3) in riparian zones of the Three Gorges Reservoir, China. The dominant species were the C₄ plants in the upstream including Changshou (CS), Fuling (FL) and Zhongxian (ZX) and the C₃ plants in the downstream in unflooding zone including Wanzhou (WZ) Badong (BD), and Zigui (ZG). C₄ plant in flooding zone was significant decreased by mean 25% compared with unflooding zone in the upstream but significantly increased the by mean 59% in the downstream. The ¹³C isotopic differences between soil and plant (Δδ¹³C) was lower than zero in both flooding and unflooding in the upstream, but was only lower than zero in flooding zone in the downstream. The proportion of C₃-derived C in soil organic carbon pool (average 74.64%) was lower for the flooding zone compared to the unflooding zone (average 87.26%) in most sites, while the proportion of C₃-derived C in LC (average 44.38%) was decreased in the flooding zone compared to the unflooding zone (69.52%) in the downstream. Additionally, the δ¹⁵N values of soil were higher than plant community in most sites, and were strongly associated with soil C and N pool content, as well as soil pH. Overall, our results revealed that soil C accumulation was primarily determined by C₃ plant in situ and new C input by existing dominant C₄ plant, whereas soil N dynamics was predictably dependent on soil relative C and N availability in response to flooding at regional scale.

Keywords: Labile and recalcitrant fraction; Riparian zone; Soil organic matter; Stable isotopes.

MeSH terms

Carbon
China
Ecosystem*
Floods
Soil*

Substances

Soil
Carbon