stocking
A ratio of the actual density of trees in an area to the ideal density that would make the fullest use of the land.
stocking: how full a forest really is
Stocking measures what proportion of a forest's growth potential is actually being used by the trees present. It expresses the density of trees as a percentage of some reference standard, usually the number of trees per hectare or the basal area (total cross-sectional area of all tree stems at breast height) that a fully productive stand of the same age and species would contain. A stand at 100% stocking is using the site fully; one at 60% has 40% of its capacity lying unused.
The reference standard, called full stocking or normal stocking, varies by species, age, site quality, and region. Foresters use yield tables or forest growth models to determine what a fully stocked stand should look like. A young plantation might be fully stocked at 5,000 stems per hectare, while a mature mixed hardwood forest might be fully stocked at 300 stems per hectare. Stocking percent is calculated by dividing actual basal area or stem count by the standard and multiplying by 100.
Why stocking matters in practice
Understocked stands, typically below 70%, waste site productivity and accumulate deadwood and brush. They also recover slowly after harvesting. Overstocked stands, above 100%, mean trees compete fiercely for light, water, and nutrients, resulting in smaller individual trees, slower diameter growth, and higher mortality from disease and stress. The optimal stocking range depends on management goals: timber production usually favors 70% to 90% stocking, while wildlife habitat or carbon accumulation may favour different densities.
Stocking is assessed by fixed-area plots or relascope sampling in the field. Plot data are compared against regional stocking tables or curves. The term comes from the old sense of stock meaning a supply or store of livestock or goods; a forest's tree population was its biological stock. The concept became formalized in German forestry during the 19th century and has remained central to forest inventory and management planning across temperate zones.
Stocking alone does not describe forest health; a stand can be 100% fully stocked but consist entirely of poor-form or diseased trees. It is one metric among many, used alongside age, species composition, diameter distribution, and site index to assess whether a forest is on track to meet its management objectives.