Moderate Hydrological Droughts Maximized CO₂ Sink in China's Largest Floodplain Lake

Area of Science:

• Environmental Science
• Ecology
• Climate Science

Background:

• Floodplain lakes play a crucial role in global carbon cycling.
• Understanding carbon dynamics in these ecosystems is essential for accurate global carbon budget assessments.

Purpose of the Study:

• To construct a spatially explicit dataset of carbon dioxide (CO2) fluxes for China's largest floodplain lake from 2003-2022.
• To investigate the primary drivers of temporal variations in CO2 flux within the lake ecosystem.

Main Methods:

• Development of a spatially explicit CO2 flux dataset.
• Statistical analysis to identify key environmental drivers of CO2 flux.
• Quantification of the impact of hydrological regime changes on CO2 uptake.

Main Results:

• Annual CO2 fluxes ranged significantly, from uptake to release, between 2003 and 2022.
• Hydrological factors, specifically water rise and recession onset, were the most influential drivers of CO2 flux.
• A delay in water rise enhanced CO2 uptake, while an earlier recession also increased uptake, but extreme drought reduced CO2 uptake significantly.

Conclusions:

• Hydrological regime and wetland vegetation are key determinants of floodplain lake CO2 flux.
• Water resource management strategies directly influence the carbon sequestration capacity of floodplain lakes.
• Findings provide critical insights for evaluating ecological impacts and advancing carbon neutrality goals through effective lake management.