An environmental science concept defining interactions among organisms, resources, and human pressures. It governs how disturbances and management actions change ecosystem structure, function, and service delivery. It does not ensure desired outcomes without monitoring, enforcement, and adaptive management of pressures. It supports protection and restoration by translating ecological evidence into measurable objectives and actions. The concept is generally stable, though metrics and monitoring methods improve over time.

Principle

Function arises from interactions among organisms and between organisms and abiotic components; energy flow, nutrient cycling, and feedbacks create system-level properties such as productivity, resilience and trophic structure.

Demonstration

A temperate forest in which primary productivity, leaf litter decomposition, soil nutrient pools, herbivore populations and predator dynamics are connected so that changes in canopy composition alter light regimes, understorey plants, soil microbes and nutrient availability.

Misapplication

Defining ecosystem boundaries by administrative lines or assuming ecosystems are closed and static systems; for example, managing a 'lake' without accounting for upstream watershed inputs and migratory species.

Consequence

Recognizing ecosystems as functional units leads to management that targets processes (e.g., restoring flow regimes, reconnecting floodplains, reestablishing keystone species) rather than isolated components, improving long-term function and services.

Reversal

Reversing the concept treats species or habitats in isolation (species-only management) rather than focusing on flows and interactions; this can maintain species but fail to sustain ecosystem processes.

Boundary

Applies at many scales from ponds to biomes; excludes purely abiotic analyses that ignore biotic interactions and excludes single-organism or purely genetic descriptions unless linked to system-level processes.

Semantic Tension

Often overlaps and sometimes competes with 'community' (biotic assemblage only) and 'habitat' (physical place); the tension lies in whether emphasis is on interacting components and processes (ecosystem) or on composition or location alone.

Synthesis

An ecosystem is a functional, interacting assemblage of organisms and their nonliving environment whose coupled flows of energy and matter produce emergent structure and processes that sustain biodiversity and ecosystem services.