Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, New Territories 999077, Hong Kong, China; Research Institute for Shanghai Pollution Control and Ecological Security, 200092, China.
Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, New Territories 999077, Hong Kong, China.
Sci Total Environ. 2020 May 10;716:137109. doi: 10.1016/j.scitotenv.2020.137109. Epub 2020 Feb 4.
Soil organic carbon (SOC) is both a product and a cause of soil development. Previous studies found that less carbon (C) is fixed by Phragmites communis than Spartina alterniflora in the Jiuduansha wetland of the Yangtze River Estuary. However, the P. communis zone presented higher contents of SOC and humus, which was mainly related to lower soil respiration (SR). It is not well known how different plants affect turnover of original SOC in the Jiuduansha wetland, and thus soil development and tidal flat evolution. In this study, in-field surveys and microcosm experiments were conducted to trace turnover of plant C and evaluate dynamics of SOC using stable C isotopic techniques. Spartina alterniflora decayed faster than P. communis, and more of its derived OC was lost through SR and leaching. Although S. alterniflora-derived OC suppressed the degradation of original SOC, it was consumed to a greater extent, making less supplementation to SOC. Phragmites communis-derived OC showed less degradability and accelerated the degradation of original SOC, but was more incorporated into new SOC and finally caused higher increase in SOC, specifically in bare tidal flat soil with poor original SOC. Overall, compared with S. alterniflora, P. communis-derived OC more effectively replaced the unstable original SOC, thereby improving the content and stability of SOC, especially for soil in early-development stages of tidal flats.
土壤有机碳（SOC）既是土壤发育的产物，也是其成因。先前的研究发现，在长江口九段沙湿地，相较于互花米草（Spartina alterniflora），芦苇（Phragmites communis）固定的碳（C）更少。然而，芦苇区具有更高的 SOC 和腐殖质含量，这主要与较低的土壤呼吸（SR）有关。不同植物如何影响九段沙湿地原始 SOC 的周转，从而影响土壤发育和滩涂演替，目前还不甚清楚。在本研究中，通过野外调查和微宇宙实验，利用稳定碳同位素技术追踪植物 C 的周转，并评估 SOC 的动态。互花米草的降解速度快于芦苇，更多的其衍生 OC 通过 SR 和淋洗而流失。尽管互花米草衍生的 OC 抑制了原始 SOC 的降解，但它的消耗程度更大，对 SOC 的补充作用较小。芦苇衍生的 OC 表现出较低的降解性，加速了原始 SOC 的降解，但更多地被纳入新的 SOC 中，最终导致 SOC 增加，特别是在原始 SOC 较差的裸露滩涂土壤中。总体而言，与互花米草相比，芦苇衍生的 OC 更有效地替代了不稳定的原始 SOC，从而提高了 SOC 的含量和稳定性，特别是对于滩涂发育早期的土壤。
