Developmental Dynamics

By definition, uneven-aged stands have three or more distinct regeneration cohorts; so, if one begins with an even-aged stand or an understocked stand, conversion to an uneven-aged structure is a long-term proposition. A minimum of two cutting-cycle harvests will be needed to recruit two additional cohorts of regeneration, and a third cutting-cycle harvest will be needed to avoid suppressing this new regeneration, especially with shade-intolerant southern pines. For the 5- to 7-year cutting cycles used for loblolly-shortleaf pine stands at CEF and elsewhere, it will be 20 to 30 years before even-aged or understocked stands are minimally reconfigured to uneven-aged structure. For species such as shortleaf pine in the Interior Highlands, where 7- to 10-year cutting cycles are common, the conversion period will be 30 to 40 years. These estimates are confirmed in data from the CEF Good and Poor Forties, where the time from high-grading harvests in 1915 to initial development of full stocking was 36 years.