Prescribed Burn

Prescribed burns are an important tool in some types of management systems in forestry. Most commonly, fire is utilized to reduce the amount of logging debris present after clear-cutting. This practice is generally undertaken to make the site more accessible to tree planters. The use of prescribed burning for this purpose means that the site does not have to be prepared using more expensive physical techniques such as scarification by heavy machinery.

Sometimes prescribed fire is also useful in developing better seedbeds for planting tree seedlings. Prescribed burns can also be used to encourage natural regeneration by particular types of trees that are economically desirable such as certain species of pines. When using fire for this purposes, it is important to plan for the survival of an adequate number of mature seed trees. If this is not accomplished, the burned site would have to be planted with seedlings grown in a greenhouse.

Prescribed burning makes available a flush of certain nutrients in ash, particularly, calcium, magnesium, potassium, and phosphorus. However, there may be little biomass of regenerating vegetation on the site immediately after a burn, and therefore there is little biological capability to take up soluble forms of nutrients. Hence, much of the nutrient content of the ash may be lost from the site during heavy rains. In addition, most of the organic nitrogen of the logging debris becomes oxidized during combustion to gaseous compounds such as nitric oxide, and the fixed nitrogen is therefore lost from the ecosystem.

The use of prescribed fire in forestry is most suitable for forest types that are naturally adapted to regeneration after wildfire, for example, most pine and boreal forests. The use of this industrial practice in other types of forests, particularly temperate rain forests, is more controversial.