About forty years ago, 155 plots of shortleaf pine (Pinus echinata) were planted in national forests across the USDA Forest Service Southern Region. The original purpose was progeny testing, but as decades passed, the study was largely abandoned. However, many of the stands remained and kept growing.
In 2018, researchers evaluated 15 of the surviving stands in the Ouachita and Ozark-St. Francis National Forests in Arkansas and Oklahoma.
The stands offered a rare opportunity to see how genetics and environment affected three important traits: tree survival, height, and diameter at breast height (DBH).
Tree survival was not affected by differences between genetic families, as the team found. However, DBH and tree height were affected by genetics – both genetic families and the source of the seeds.
Shortleaf pine has wide geographic distribution (22 states). Seeds from outside of Arkansas and Oklahoma could respond differently. In addition to the role of genetics, precipitation gradients or soil differences may have caused some of the variation in growth.
The information can guide managers in their planting choices for forest restoration or seed orchards.
Shaik Hossain, now of Alabama A&M University, led the study, with five Forest Service co-authors representing all three deputy areas: Research, State and Private, and the National Forest System.