Green and Dry-Weight Equations for Above-ground Components of Planted Loblolly Pine Trees in the West Gulf Region

Prediction equations based on 130 sample trees from thinned and unthinned loblolly pine (Pinus taeda L.) plantations in central Louisiana re presented for the green and dry weights of aboveground tree components. Sample trees ranged from 2 to 21 in. dbh, 18 to 94 ft in height and from 9 to 55 yr in age. Significant differences in partial stem weight between trees from thinned and unthinned stands required development of separate sets of weight ratio equations. The range of the studies' observations i creases the predictive applicability ofplanted loblolly pine biomass equations. South. J. Appl. For. 11(4):212-218. Loblolly pine is the most important commercial softwood species in the South and the most widely planted southern pine. This importance created a need to develop a growth and yield prediction system for loblolly pine plantations in the West Gulf region. 9It also led to creating new stem profile functions and new volume equations for trees from thinned and unthinned stands. These equations are being published separately. • Furthermore, given re• Funding for this project was provided through the Southeastern Regional Biomass Energy Program (SERBEP), which is administered by the Tennessee Valley Authority for the U.S. Department of Energy. 2 Baldwin, V. C., Jr. and D. P. Feduccia. 1987. Loblolly pine growth and yield prediction in West Gulf region plantations. Res. Pap. SO-236. 27 p. s Baldwin, V. C., Jr.; Feduccia, D. P. Treevolume and stem-profile functions for unthinned and thinned plantation grown cent technological advances that make utilization of all tree components feasible and profitable, it was also advisable to develop equations to predict yields of branch and foliage material from these plantations. Weight is the best measure of yield for these nonbole components, and this measure is becoming increasingly popular for bole products, too. Hence, new weight equations were developed to meet this need. This paper presents equations that predict green and dry weight of boles (ib or ob) to any top diameter limit, branches (ib or ob), or foliage of loblolly pine trees in thinned or unthinned plantations in the West Gulf region. Examples of how to apply the equations are also given. New weight equations were needed because most existing plantation loblolly pine weight equations were inadequate. Many were developed from trees sampled in the Southeast (e.g., Bailey et al. 1985, Edwards and McNab 1979, Flowers 1978). Their applicability in the West Gulf region is questionable. Clark (1983) has shown that site and geographic differences in tree biomass are significant within a species and that "... biomass estimates for marketing purposes should be made using only locally developed or loloblolly pines in the West Gulf region. In review. cally tested species equations..." In this same paper Clark also pointed out that natural pine biomass equations might give acceptable green-weight predictions in plantations, but dry-weight predictions would not be applicable. Thus, the natural loblolly pine equations developed by Matney (1977) or Lenhart et al. (1980) would not be adequate in West Gulf plantations. Furthermore, the plantation loblolly pine biomass equations developed by Hicks et al. (1972) and Hyink et al (1972) only predict bole weights And the Nelson and Switzer (1975) and Shelton et al. (1984) equations may only be accurate when used to predict tree component weights in relatively young unthinned plantations. The Gibson et al. (1985) unthinned plantations biomass equations have somewhat limited application because their loblolly pine data set did not contain planting spacing or age variability. In all of the studies mentioned above, data were not available for plantation grown trees over 35 yr old, for diameter at breast height (D) generally over 14 in. (there were only 3 trees with D greater than 14 in sample), and total height (H) greater than 75 ft (2 taller trees had been sampled). Furthermore, no publicly available equations have been developed heretofore to predict biomass of tree components in thinned West Gulf loblolly pine plantations.