Large slow-growing hydrophytes increase wetland carbon storage

Area of Science:

• Ecology
• Climate Science
• Conservation Biology

Background:

• Wetlands are critical carbon sinks for climate change mitigation.
• The role of plant diversity in wetland soil carbon storage is not well understood.
• Terrestrial plant diversity often enhances soil carbon, but wetland dynamics differ.

Purpose of the Study:

• To investigate the impact of trait-based plant diversity (functional diversity) and composition (functional identity) on soil carbon storage in natural wetlands.
• To determine factors that modulate these relationships, such as nutrient availability, invasive species, water levels, and human disturbance.

Main Methods:

• Analysis of data from 1,268 natural wetlands in the US National Wetland Condition Assessment (NWCA).
• Examination of how functional diversity and functional identity influence soil carbon stocks.
• Assessment of environmental factors (nutrients, non-native stress, water levels, disturbance) on these relationships.

Main Results:

• Functional diversity showed a minimal effect on wetland carbon stocks.
• Elevated soil nutrients and non-native plant stress reduced the influence of functional diversity.
• Soil carbon storage was higher in wetlands dominated by large, slow-growing, highly hydrophytic plants.
• The positive effects of functional identity were dependent on high water levels and low human disturbance.

Conclusions:

• Wetland plant functional identity, rather than diversity, is a key driver of soil carbon storage.
• Conservation and restoration efforts should prioritize wetlands with specific plant traits (large, conservative, hydrophytic) and favorable conditions (high water, low disturbance) for climate mitigation.
• Understanding these factors is crucial for effective wetland management for climate goals.