Closed ecosystems extract energy through self-organized nutrient cycles

Area of Science:

• Ecology
• Thermodynamics
• Microbial Ecology

Background:

• Earth's ecosystems are largely closed to matter and exhibit self-organizing, stable nutrient cycles.
• Existing ecological models fail to replicate the observed self-organization and stability in natural ecosystems.
• Understanding these dynamics is crucial for modeling planetary-scale ecosystems.

Purpose of the Study:

• To develop a conceptual model explaining the self-organization and stability of closed microbial ecosystems.
• To incorporate bioenergetics of metabolism into ecological frameworks.
• To identify mechanisms driving nutrient cycle stabilization in diverse communities.

Main Methods:

• Development of a conceptual ecological model integrating metabolic bioenergetics.
• Analysis of thermodynamic feedback loops within the model.
• Simulation of nutrient cycling dynamics in microbial communities of varying diversity.

Main Results:

• A key thermodynamic feedback loop was identified, enabling stable nutrient cycles in metabolically diverse communities.
• Highly diverse communities self-organized to extract significantly more energy (approx. 10% of maximum) compared to randomized communities (approx. 100-fold less).
• Increasing diversity correlated with stable nutrient cycle fluxes, but higher light energy led to more variable and species-dependent fluxes.

Conclusions:

• Self-organization is a critical factor promoting energy extraction efficiency and stability in complex ecosystems.
• The findings highlight the role of bioenergetics in ecosystem self-organization and resilience.
• These principles apply to diverse ecosystems, from microbial mats to planetary scales, without central coordination.