Comparing 16-year-old shortleaf and loblolly pine growth and yield on a north Mississippi afforested site

Abstract

This analysis compares the growth and yield of 16-year-old shortleaf pine (Pinus echinata Mill.) and loblolly pine (Pinus taeda L.) planted on retired fields near Holly Springs in north Mississippi. The 1-0 bareroot shortleaf seedlings were planted in early March of 2005, while bareroot 1-0 loblolly pine 2nd-generation seedlings were planted during the third week of March in 2005. For both species, the site was subsoiled. Within the plantations of each species, four plots were established for each species and total height and diameter at breast height (dbh) were measured. Volumes were then estimated using appropriate combined-variable volume equations. Loblolly pine had substantially greater growth rates relative to shortleaf pine, producing on average across the four plots (n = 4) 48.4 m-2 of basal area ha-1. This basal area was 42.6% greater than the 34.0 m-2 of basal area ha-1 observed within the shortleaf pine. For merchantable volume, defined as all trees with a dbh of 10.16 cm and greater up to a diameter-outside bark (dob) of 5.08 cm, the loblolly pine m-3 volume ha-1 of 424 was 2.36 times greater than that of shortleaf pine. Merchantable volumes were converted to tons and a revenue of $3.61 was assumed per ton of pulpwood. A theoretical 3rd row thinning with no logger select of the remaining rows was conducted – hence the thinning was assumed to remove 33% of the standing merchantable yield. Loblolly pine had a stumpage value of $97.39 ha-1 which was 136% greater than the shortleaf pine economic value of $41.23 ha-1.