Total and Merchantable Stem Volume Equations for Midrotation Loblolly Pine (Pinus taeda L.)

Abstract Combined-variable (D2H) and exponential-ratio equations are presented for predicting stem volume of loblolly pine in the Atlantic Coastal Plain of the southeastern United States. The equations were derived using 985 stems in a replicated study with first- and second-generation open-pollinated families across four levels of weed control and fertilization treatments. Prediction equations include inside- and outside-bark total volume and inside- and outside-bark merchantable volume to any top-limit diameter. Each equation has an R2 of 0.962 or higher and root mean square error of 0.354 ft3 or lower. The diversity of genetic backgrounds and silvicultural treatments gives the equations broad applicability in situations such as first thinning cruises, tree improvement progeny tests, silviculture research trials, and continuous forest inventory.