Mid-intertidal mangrove belts concentrate ecosystem multifunctionality in a semi-enclosed estuary

Area of Science:

• Coastal Ecology
• Ecosystem Science
• Environmental Science

Background:

• Mangrove ecosystems are vital coastal interfaces influencing nutrient cycling, carbon sequestration, and biodiversity.
• Understanding how mangrove multifunctionality responds to tidal gradients is crucial but remains poorly understood.

Purpose of the Study:

• To assess plant communities, soil properties, microbial structure, greenhouse gas (GHG) fluxes, and ecosystem multifunctionality (EMF) across different mangrove zones.
• To determine the impact of spatial gradients in tidal regimes on mangrove ecosystem functions.

Main Methods:

• Evaluated 33 indicators of EMF across three mangrove zones in Qinglan Bay, Hainan, China (marine-influenced, mid-intertidal, terrestrial-edge).
• Analyzed plant diversity, soil organic carbon, total nitrogen, available nitrogen and potassium, and microbial community structure.
• Quantified EMF by normalizing and averaging indicators across vegetation, soil, microbial, and GHG attributes.

Main Results:

• The mid-intertidal zone (Site II) exhibited significantly higher plant diversity and evenness, along with the highest soil organic carbon, total nitrogen, and available potassium.
• Microbial networks in the mid-intertidal zone showed higher modularity and lower connectivity, indicating compartmentalized interactions.
• Ecosystem multifunctionality (EMF) peaked in the mid-intertidal zone, correlating positively with soil nutrients and moderate tidal activity.

Conclusions:

• Intermediate tidal positions in mangrove ecosystems create favorable conditions for soil nutrient dynamics and support higher functional diversity.
• Environmental constraints at extreme tidal positions (strong marine forcing or phosphorus enrichment) reduce EMF.
• Findings support zoning strategies for coastlines that balance ecosystem services with land-use needs, such as aquaculture and agriculture.