Climate and vegetation jointly determine the interannual variation of net ecosystem CO2 fluxes over 12 years in a restored coastal wetland

Abstract

Wetland CO₂ sinks represent a long-term, effective strategy for mitigating climate change and enhancing carbon sequestration. Many regions have adopted ecological restoration practices, such as “returning farmland to wetlands” to strengthen the CO₂ uptake capacity of ecosystems. However, the respective contributions of vegetation dynamics and climatic factors to ecosystem CO₂ sequestration during this process remain poorly understood. This study utilizes 12 years of CO₂ flux data, meteorological data, and remote sensing imagery from a restored coastal salt marsh to investigate how vegetation and climate jointly influence net ecosystem exchange (NEE) across multiple time scales and different restoration durations. The results demonstrate that both vegetation and climate provide critical insights into NEE dynamics. Integrating vegetation and climate data enhances the accuracy of NEE predictions, indicating their combined influence on ecosystem CO₂ sequestration. As the time scale increases, vegetation exerts progressively stronger control over NEE, although climatic factors remain the primary driver of its variation. Moreover, vegetation recovery during restoration enhances its regulatory effect on NEE, gradually reducing the relative influence of climate. These findings deepen our understanding of the mechanisms driving NEE of CO₂ and offer valuable guidance for predicting and optimizing coastal wetland carbon sink functions.