Dynamics of Stand Growth and Yield Over 29 Years in a Loblolly Pine Source Trial in Arkansas

Stands representing 36 unselected, rangewide sources of loblolly pine in a 29-year-old geographic source trial in southwestern Arkansas were compared in terms of stem diameter, dominant height, mortality and stand basal area production trends over time. Significant geographic-source differences were maintained through age 29 for Dbh and dominant height, with eastern sources (particularly East Coast) maintaining an approximately constant percent superiority of 3-8% after age 11. By the study's conclusion the superiority of eastern-origin trees over western in volume per tree was 18%. Late mortality differed little between East Coast and local Arkansas stands through age 26, but subsequently diverged. Stand basal area production was superior in East Coast origin 'stands through age 26, but declined to no significant difference by age 29. The observed declines In yield superiority of East Coast over local stands after age 26 could not be shown to result from any difference in "competitive ability"; rather, It is hypothesized that the faster-growing East Coast stands reached a similar maximum size-density trajectory four years sooner. Given the value and cost advantages of larger piece size, these results favor use of East Coast material on moist sites In Arkansas. However, for the early growth benefits of source movement to be maintained through the long term, the fast-growing eastern-origin stands must be aggressively managed to minimize yield reductions associated with severe competitive stress.

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Author(s): Cheryl B. Talbert, M. R. Strub

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1987