GONG Xiaojie1,2,3, YUAN Xingzhong1,2,3,4，LIU Tingting1,2,3, KONG Weiwei1,2,3, LIU Huan1,2,3, WANG Xiaofeng1,2,3
(1. Chongqing Key Laboratory of Wetland Science Research of the Upper Yangtze River, Chongqing 401331, China; 2. College of Geography and Tourism, Chongqing Normal University, Chongqing 401331, China; 3. Field Scientific Observation and Research Station for Earth Surface Ecological Processes in Three Gorges Reservoir area, Chongqing 401331, China; 4. Faculty of Architecture and Urban Planning, Chongqing University, Chongqing 400030, China)
Abstract：The greenhouse gases (GHGs) emission from freshwater ecosystems, an important natural source of atmospheric greenhouse gases, had attracted extensive attention worldwide. As an important part of the freshwater ecosystem, aquatic plants played important roles in the biogeochemical process of water biogenic elements. Exploring the influence of aquatic plants on the greenhouse gas emission from freshwater ecosystems was of great significance to the understanding of ecosystem functions. In this study, based on current researches on the relationship between aquatic plants and greenhouse gas emissions from freshwater ecosystems, effects of aquatic plants on the dynamic process of GHG emission from freshwater ecosystems were discussed to propose that the water area with rich aquatic plants will be hotspots of the greenhouse gas emission. Meanwhile, on account of the multiplicity of life form and species of aquatic plants, the GHG emission from the freshwater ecosystem showed characteristics of high variability and uncertainty. The effect mechanisms of aquatic plants on CO2, CH4 and N2O emissions from freshwater ecosystems were further summarized: 1) the mechanical effects, including the gas transport channel effect and the retention effect of floating leaf plants; 2) the photosynthesis/respiration of aquatic plants affects the carbon cycle in water, while the decomposition of litters of aquatic plants provides fresh sources of carbon and nitrogen for the metabolism of aquatic organisms which increases the greenhouse gas production rate; 3) aquatic plants affect the generation and emission of CH4 and N2O by changing the anaerobic environment of the rhizosphere; 4) the aquatic plant community can change the distribution pattern of water ecological factors and affect the heterotrophic metabolism of aquatic organisms. Based on the current research status, this paper proposed that the further study should focus on influences of aquatic plant species, life forms and growth metabolism on the dynamic process of the greenhouse gases emission from water under different scales and different habitat conditions. In addition, a dynamic model of the greenhouse gas emission should be built based on the scale of aquatic plant community and the monitoring method and the estimation model should be optimized in further researches. This study can provide a theoretical basis for researches on the greenhouse gas emission in freshwater ecosystems of China.
Key words: aquatic plant; freshwater ecosystem; greenhouse gas; influence mechanism
EARTH AND ENVIRONMENT Vol.48, No.4, Tot No.336, 2020, Page 496-509