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Productivity and economic viability of hybrid sweetgum in Oklahoma, Texas, and Louisiana

Lewis, Jacob
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Abstract

The pulp and paper industry of the south-central U.S., which relies partly on hardwood timber, has faced supply chain issues due to excessive hardwood mortality, harvesting/transportation challenges, and heightened demand from the oil and gas industries. Moreover, demand for wood-based renewable energy is increasing. One solution is to utilize highly-productive and site-tolerant species to generate timber, pulp, and biofuel feedstock in a plantation setting. While sweetgum (Liquidambar styraciflua) is a potential hardwood candidate, research suggests hybrid sweetgum (Liquidambar formosana x styraciflua) exhibits greater productivity under highly-controlled conditions. My study, spanning southeastern Oklahoma, northeastern Texas, and northwestern Louisiana explored this at an operational scale. Thirty-five stands were sampled, eleven with half-sib families of sweetgum and 24 with hybrid clones. Stand ages ranged from 6-11 years for half-sibs and 5-8 years for hybrids. Site conditions varied greatly, but planting densities and management intensities were relatively similar. Hybrids had greater wood specific gravity (0.49 vs 0.46 g/cm3) and stem bulk density (0.94 vs 0.87 Mg/m3). Decreased stem taper also meant the hybrids were much heavier for a given stem diameter. Ultimately, hybrids exhibited significantly faster growth than the half-sibs at the same age (15.8 vs 11.4 Mg/hectare/y). From an economic standpoint, this increased growth rate allowed the hybrids to excel, despite the higher cost of seedlings. The hybrids produced significantly better economic returns than the half-sibs under every management scenario and market scenario tested. For example, the half-sib stands produced a mean LEV of -$1,564.99/ha under pulp-sawtimber management and average market conditions, while the hybrid stands produced a mean LEV of $932.20/ha. In conclusion, my study confirms hybrid sweetgum’s viability by demonstrating its superior productivity and greater economic returns.

Date
2023-12
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