stool

A stool is the basal portion of a woody or herbaceous plant that remains alive in the ground after the main stem has been cut down close to soil level. Instead of dying back completely, the stool develops multiple new shoots from dormant buds in the remaining stem tissue and root crown. This regeneration produces a characteristic branched form that resembles the legs of a three or four-legged stool, which is the origin of the term.

Coppicing and pollarding are the primary practices that rely on stool formation. In coppicing, hardwoods such as hazel, ash, and oak are cut at ground level on a rotation of 5 to 20 years, depending on the species and end use. The stool may produce 5 to 15 new stems from a single cutting cycle. Pollarding follows the same principle but the initial cut occurs higher up the trunk, typically 2 to 3 meters above ground, creating an elevated head that resproutes. Both methods have been used for centuries to harvest timber, fuel wood, and poles without replanting.

The productivity and longevity of a stool depend heavily on species selection and site conditions. Vigorous species like willow can be coppiced annually for decades or even centuries on the same stool. Poor drainage, frost heave, disease pressure, or grazing damage can kill stools or reduce their vigor. A healthy stool that is allowed to regrow unchecked will eventually revert to single-stem or multi-stem tree form if not cut again.

In modern forestry, stool-derived regrowth is sometimes considered a disadvantage because it produces multiple stems rather than the single straight bole preferred for dimensional timber. However, coppice systems remain economically viable for biomass production, particularly in short-rotation coppice schemes using willow or poplar clones harvested every 3 to 5 years. The stool's ability to regenerate without replanting reduces establishment costs and soil disturbance compared to replanting from seed or transplants.

Stool diameter and vigor typically decline over successive cutting cycles as the plant ages or if the stool is damaged during harvesting. Repeated cutting cycles can eventually exhaust a stool, requiring deliberate management decisions about whether to allow rejuvenation through a longer rest period, accept lower yields, or clear and replant. Waterlogging, root disease, and mechanical damage during cutting or extraction are common causes of stool mortality in commercial systems.