Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (CAS), Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2023 Jun 15;877:162690. doi: 10.1016/j.scitotenv.2023.162690. Epub 2023 Mar 8.
Floodplain lakes share characteristics of both deep and shallow lakes throughout any given year. Seasonal fluctuations in their water depth drive changes in nutrients and total primary productivity, which directly and indirectly affect submerged macrophyte biomass. To investigate how water depth and environmental variables affect submerged macrophyte biomass, we surveyed six sub-lakes in the Poyang Lake floodplain, China, during the flood and dry seasons of 2021. Dominant submerged macrophytes include Vallisneria spinulosa and Hydrilla verticillata. The effect of water depth on the biomass of these macrophytes varied between the flood and dry seasons. In the flood season, there was a direct effect of water depth on biomass, while in the dry season only an indirect effect was observed. During the flood season, the direct effect of water depth on the biomass of V. spinulosa was less than the indirect effect, with water depth primarily affecting the total nitrogen, total phosphorus and water column transparency. Water depth directly, positively affected H. verticillata biomass, with this effect being greater than the indirect effect by affecting the carbon, nitrogen and phosphorus content in the water column and sediment. During the dry season, water depth affected H. verticillata biomass indirectly through sediment carbon and nitrogen content, while for V. spinulosa, the effect on biomass was indirect through carbon content of the sediment and water column. The main environmental variables affecting submerged macrophyte biomass in the Poyang Lake floodplain during the flood and dry seasons, and the mechanisms through which water depth affects dominant submerged macrophyte biomass, are identified. An understanding of these variables and mechanisms will enable improved management and restoration of wetland.
洪泛区湖泊在任何给定年份都具有深湖和浅湖的特征。其水深的季节性波动会导致养分和总初级生产力发生变化，这直接和间接影响着淹没植物的生物量。为了研究水深和环境变量如何影响淹没植物的生物量，我们在 2021 年丰水期和枯水期对鄱阳湖洪泛区的 6 个亚湖泊进行了调查。优势淹没植物包括苦草和黑藻。水深对这些植物生物量的影响在丰水期和枯水期有所不同。在丰水期，水深对生物量有直接影响，而在枯水期只观察到间接影响。在丰水期，水深对苦草生物量的直接影响小于间接影响，水深主要影响总氮、总磷和水柱透明度。水深直接、积极地影响黑藻的生物量，其影响大于通过影响水柱和沉积物中的碳、氮和磷含量产生的间接影响。在枯水期，水深通过沉积物碳和氮含量间接影响黑藻的生物量，而对苦草的影响则是通过沉积物和水柱中的碳含量间接产生的。确定了鄱阳湖洪泛区在丰水期和枯水期影响淹没植物生物量的主要环境变量，以及水深影响优势淹没植物生物量的机制。了解这些变量和机制将有助于湿地的管理和恢复。
