Free thinning

n. A thinning that removes trees to control spacing and favor desired trees using a combination of criteria without regard for crown class (Helms 1988).

 

  • Discussion

 

Thinning to reduce canopy bulk density and increase canopy base height is quite different from thinning for growth and yield objectives -- crown spacing becomes more important than tree vigor. Free thinning is often the best thinning method when the objective is to mitigate crown fire potential. Desired trees for retention are fire resistant and contribute little available canopy fuel per unit of growing space. Desired trees are selected for retention not solely by crown class or vigor, but also on their location relative to neighbors.

 

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Some applications may indicate even crown spacing, while others may require that trees be left in small groups with relatively large gaps between groups. Free thinning is used to achieve those goals.

 

Nonetheless, free thinning is not license to select trees however one likes; a specific thinning objective is required before properly implementing a free thinning.