A comparison of two groups of yield plots representative of loblolly pine plantations in the Southeastern United States.
Stand growth and productivity during the first decade for two groups of yield plots established in managed loblolly pine plantations growing in the Southeastern United States were compared. Both groups were established on site-prepared areas in operational stands growing under intensive management. Group 1 plots represented stands established during the 1990s with open pollinated single family or multi-family stock and received silvicultural treatments typical of the period. Group 2 plots were established approximately 10 years later in the same physiographic region with clones and subjected to site-suitable silvicultural treatments. After accounting for the difference in age, average height growth of dominant and codominant trees (site trees) was not significantly different between the groups. Individual tree diameter and height growth were different resulting in stem form characteristics that were significantly different for the two groups. Characteristics that negatively affect stem quality were generally reduced in the clonal plantings suggesting a greater proportion of large trees will be suitable for sawtimber. Simulations with a growth and yield model showed increased productivity and future potential value for plantations established with clones.