A New Tree Classification System for Southern Hardwoods

A new tree classification system for southern hardwoods is described. The new system is based on the Putnam tree classification system, originally developed by Putnam et al., 1960, Management ond inventory o f southern hardwoods, Agriculture Handbook 181, US For. Sew., Washington, DC, which consists of four tree classes: (1) preferred growing stock, (2) reserve growing stock, (3) cutting stock, and (4) cull stock. Tree classes under the Putnam system are used as a basis for planning artial cuttings and for developing marking rules in southern hardwood forests. However, there are critical problems associated with field use of this system: ( I ) 5 t e reserve growing stock class is too broad and poorly defined; (2) in most partial cutting operations, the timber marker must decide which reserve growing stock trees to cut and which ones to leave; (3) the timber marker must try to mark the stand to some prescribed, quantitative level of residual density; and (4) the timber morker often is forced to either leave low-quality trees or cut high-quality trees to maintain the target residual density uniformly across the stand. Overall stand quality often is compromised through use of the Putnom tree classification system and through strid adherence to the concept of stand density management. Our new tree classification system consists of five classes used only for sawtimber-sized trees: (1 1 preferred growing stock, (2) desirable growing stock, (3) occeptoble growing stock, (4) cutting stock, and (5) cull stock; and two classes used only for poletimber-sized trees: (1 superior poletimber stock and (2) inferior poletimber stock. Doto from one of our hardwood thinning studies are used to illustrate differences between the Putnam and the new tree classification systems. Potential uses and odaptotions of the new tree classification system are descihed also.