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Chinese Journal of Applied Ecology ›› 2025, Vol. 36 ›› Issue (12): 3787-3798.doi: 10.13287/j.1001-9332.202512.033

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Enhancement of lake CO2 uptake by pen removal and ecological restoration and its driving factors

JIA Lei1, ZHANG Mi1,2*, XIAO Wei1,2,3, PU Yini4, SHI Jie1, GE Pei1, QIAO Heng1, LUO Shiji1, ZHANG Shenbao1   

  1. 1School of Ecology and Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China;
    2Key Laboratory of Ecosystem Carbon Source and Sink, China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China;
    3Yale-NUIST Center on Atmospheric Environment, State Key Laboratory of Climate System Prediction and Risk Management, Nanjing University of Information Science and Technology, Nanjing 210044, China;
    4Office of Development Planning and Discipline Construction, Chengdu University of Technology, Chengdu 610059, China
  • Received:2025-06-05 Revised:2025-09-11 Online:2025-12-18 Published:2026-07-18

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Abstract: Lakes are crucial for the global carbon cycle. The impacts of aquaculture and “pen removal and lake ecological restoration” on lake carbon source and sink functions remain unclear. We continuously monitored CO2 fluxes in the aquaculture zones of East Lake Taihu during the aquaculture period (2018) and the ecological restoration period (2019-2020), to assess the effects of restoration on lake CO2 flux and its driving factors. The results showed that, regardless of the aquaculture or restoration stage, seasonal variations of CO2 fluxes followed a consistent pattern: net CO2 uptake during the growing season (May-October) and near-zero fluxes during the non-growing season (December-March). Diurnal CO2 flux patterns characterized by daytime uptake and nighttime release, which became more pronounced after restoration, with a significant increase in daytime uptake and a slight rise in nighttime emission. The reduction in external organic carbon input and the shift in dominant macrophyte communities from submerged plants to floating-leaf plants after restoration substantially enhanced net CO2 uptake of East Lake Taihu, with growing-season CO2 uptake increasing from 182.03 g CO2·m-2·a -1 in 2018 (aquaculture stage) to 384.17 and 629.19 g CO2·m-2·a -1 in 2019 and 2020, respectively. The diurnal CO2 flux dynamics were primarily driven by solar radiation. Both light-use efficiency and photosynthetic capacity of aquatic plants improved after restoration. At the daily scale, CO2 fluxes during the aquaculture period were regulated by temperature, solar radiation, and wind speed. After restoration, the effect of wind speed became insignificant, the temperature sensitivity (Q10) of daytime uptake increased from 2.44 in 2018 to 3.16 in 2019 and 3.03 in 2020; and the Q10 of nighttime emission declined from 10.20 in 2018 to 1.17 in 2019 and 5.14 in 2020. On the monthly scale, during the aquaculture phase, total nitrogen concentration was the primary controlling factor for lake CO2 flux, while the normalized difference vegetation index (NDVI) was the primary controlling factor for diurnal lake CO2 flux. After the cessation of aquaculture and the restoration of the lake, solar radiation and temperature became the primary controlling factors for lake CO2 flux, and the sensitivity of diurnal lake CO2 flux to changes in NDVI increased.

Key words: subtropical lake, aquaculture, pen removal and ecological restoration, CO2 flux, driving factor