To become operational at the level of actual landscapes, the principle of sustainable development needs to be broken down into criteria and indicators (C&I), the latter of which can be measured repeatedly to examine whether or not change is taking place in the direction stated by relevant policies. Repeated measurement of a specific variable is referred to as monitoring. Indicators can be monitored at multiple scales ranging from whole countries to regions of a country, or local forest management units (look at the picture on the right).

As a logic step linked to monitoring, assessment denotes the analysis and synthesis of monitoring data and observations. To facilitate informed decision-making on forest policy and management related to the level of sustainability in the “strong” sense, performance targets should be developed and combined with results from monitoring. However, performance targets and tools for monitoring and assessment are not commonly available. Nevertheless there are good appearing examples from both terrestrial and aquatic landscapes.