Many communities depend on forests directly or indirectly for a wide range of forest-based goods and services. The sustainable provision of these services is clearly linked to the productive capacity of the forest. If this capacity is exceeded there is the risk of ecosystem decline and collapse.

Growing stock is defined as the standing volume of the trees in a forest above a certain minimum size. Higher growing stock signifies more standing biomass, which often translates to better forest conditions. But it is important to note that standing tree volume alone is not a sufficient metric for detailed analysis of forest health. For example, future wood supply is highly dependent on the diversity and distribution of tree species and ages within tree stands.

Frequent disturbance of forested areas by logging can limit forest productivity, reduce biodiversity, increase soil compaction and erosion, and change nutrient and fire dynamics. Long cycles of artificial disturbance (>100 years) are less likely to negatively impact natural processes and characteristics.

Selective, thinning, and clearcut logging can disturb the forest floor and potentially reduce re-growth of trees. Re-planting trees of he same native mix as occurred in a logged forest can partially mitigate the impact.

Clear-cutting the trees from forest lands has a variety of temporary and long-term effects. These include geomorphological (erosion), hydrological (e.g., desiccation, modified flow paths), ecological (e.g., loss of intact forest habitat), and economic (short-term economic gains, potential long-term losses).

Clear-cutting forests is an efficient way to extract wood from a forested area. There are a variety of impacts of this type of logging that may or may not be mitigated by clearcut size and tree re-planting. These impacts include geomorphic effects (e.g., landslides), change in soil flora and thus nutrient cycling, loss or change in faunal species diversity, and the creation of habitat edges.

Net growth is the rate of total tree growth minus losses to mortality, extraction, fire, and other causes.

Sustainable forests and forestry generally implies that the rate of removal of forest material does not exceed the rate of growth, within and across age classes and tree types. This could be expressed as tons or volume of tree stems, or other metrics.

This indicator refers to the loss/removal of trees from commercially-used forests. This could be measured in volume, # trees, or other metrics.

The total area of timberland (forest used for extraction) can be expressed as units of area, fraction of total forest area, or fraction of the total landscape.