Contextual explanation: Ongoing maintenance of interconnected systems for future viability.
Long-term sustainability is best understood as the ongoing process of maintaining environmental, social, and economic systems in a balanced and resilient state, ensuring that future generations can meet their needs without compromising the integrity of these systems.

Themes: Interdependence and stewardship. 
The theme of interdependence is central to long-term sustainability, as it highlights the complex relationships between ecological, social, and economic domains. Stewardship is also a key theme, emphasising responsible management and care for resources to support enduring well-being.

Nuance: Balancing present and future needs. 
What distinguishes long-term sustainability within its category is the focus on balancing current resource use and development with the preservation of system health and capacity for future generations. This nuance involves proactive planning, adaptive management, and a holistic perspective that integrates multiple domains over extended timeframes.