Plant-plant interactions vary greatly along a flooding gradient in a dam-induced riparian habitat

Liu Ying; Wang Yanfeng; Wu Wenzhou; Ding Zhi; Ma Maohua; Huang Ping; Wu Shengjun; Lou Yanjing

doi:10.3389/fpls.2023.1290776

Plant-plant interactions vary greatly along a flooding gradient in a dam-induced riparian habitat

Front Plant Sci. 2023 Nov 24:14:1290776. doi: 10.3389/fpls.2023.1290776. eCollection 2023.

Authors

Liu Ying¹, Wang Yanfeng², Wu Wenzhou¹, Ding Zhi^{3

4}, Ma Maohua¹, Huang Ping¹, Wu Shengjun¹, Lou Yanjing⁵

Affiliations

¹ The Three Gorges Institute of Ecological Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, China.
² Institute of Tourism and Culture, Chongqing Business Vocational College, Chongqing, China.
³ State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
⁴ Chongqing Engineering Research Center for Remote Sensing Big Data Application, School of Geographical Sciences, Southwest University, Chongqing, China.
⁵ Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China.

Abstract

Plant-plant interactions under extreme environmental stress are still controversial. The stress gradient hypothesis (SGH) proposes that facilitation prevails under extreme environmental stresses, while an alternative view states that facilitation collapses or even switches back to competition at the extreme end of stress gradients. However, how the relationship between plant-plant interaction and periodic extreme flooding stress varies and its underlying mechanism are still unclear in a dam-regulated riparian ecosystem. We established a controlled experiment using two dominant species pairs (Cynodon dactylon-Cyperus rotundus and C. dactylon-Xanthium sibiricum) in the water level fluctuating zone of the Three Gorges Dam to examine their growth responses to the periodic extreme flooding stress. The results showed that as flooding stress increased, the competitive effect of C. dactylon on X. sibiricum shifted to facilitation, whereas the effect of X. sibiricum on C. dactylon maintained a strong inhibition. The plant height of X. sibiricum was the most important driver of the interaction between X. sibiricum and C. dactylon along the flooding gradient. The net effect of C. dactylon on C. rotundus shifted from neutral to negative, and the inhibitory effect of C. rotundus on C. dactylon became stronger at the extreme end of flooding stress. The root biomass of the two species was the key trait regulating their interaction with increasing flooding stress. Overall, the SGH was partially supported along our periodic extreme flooding stress gradient. Aboveground resource (light) might be the dominant factor driving the response of the interaction between annual plants and perennial clonal plants to periodic flooding stress, whereas belowground resource (water and nutrients) was probably the dominant factor for perennial clonal plants. Our study will help to further understand the environmental responses of plant-plant relationships and their regulatory mechanism, and the succession of riparian plant communities under extreme environmental changes, providing a basic theoretical basis and data support for the ecological restoration and management of riparian wetland vegetation.

Keywords: Bermuda grass; functional traits; interspecific relationships; reservoir riparian zone; stress gradient hypothesis; water fluctuation.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The National Natural Science Foundation of China (No. 42101074), the Three Gorges’ follow-up scientific research project from Chongqing Municipal Bureau of Water Resources (No. 5000002021BF40001), and the devices of AutoSIF-1(23A00265, 23A00266) supported this work.