silviculture a unit of harvest or regeneration in group selection —note 1. the minimum size of a group depends primarily on (a) the creation of microclimate conducive to establishment of desired regeneration of particular tolerance, and (b) the area needed for safe felling and yarding of harvested trees —note 2. group size is often expressed as a function of surrounding tree height; its boundary may be defined as at the drip-line of edge trees —see group selection, incident command system, patch, regeneration method This definition last updated 10/27/2008