Articles · Open Access Policy
Abstract
Freshwater wetlands are one of the most environmentally meaningful ecosystems in the world and make incredible contributions to the storage of carbon and the fluxes that occur throughout the planet. Though these ecosystems comprise 5-8% of all land on the ground, they hold 20-30% of the carbon stock on the planet, making them important natural climate regulatory systems. The purpose of this review is to describe the contributions of freshwater wetlands to the global carbon cycle, specifically with respect to the greenhouse gas emissions produced, carbon storage functions, and the relationship of hydrology, plant community composition, and anthropogenic stressors on these functions. Evidence from an extensive body of peer-reviewed literature and an empirical study of a freshwater wetland located in a tropical humid zone has been synthesized in order to assess the net ecosystem carbon balance; seasonal patterns of emissions of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), and factors that affect the timing of transitions between carbon sources and sinks in wetlands. Findings show that carbon sequestration rates vary considerably between different wetland types (ranging from 6.3 g C m⁻² yr⁻¹ to 42.7 g C m⁻² yr⁻¹). Climate factors that are shifting more and more wetland ecosystems from carbon sinks to carbon sources include increasing temperature, changing patterns of precipitation, increasing salinity, and the presence of microplastics. The study indicates an urgent need to establish integrated monitoring systems, restoration initiatives, and policies aimed at maintaining freshwater wetlands as carbon sink systems. The results of this study will provide critical guidance for developing approaches to mitigate climate change through ecosystem-based adaptations, as well as achieving international carbon neutrality targets.