Comparing Growth of Hybrid and Native Sweetgum Trees in the Western Gulf Region

Jim Crocker
28th June, 2024

Comparing Growth of Hybrid and Native Sweetgum Trees in the Western Gulf Region

The 16 operational plantation sites used to demonstrate the superior productivity of hybrid sweetgum (Liquidambar formosana x styraciflua) over native sweetgum (L. styraciflua) are distributed across the Western Gulf Region in Oklahoma, Texas, and Louisiana.

Image adapted from: Lewis et al. / CC BY (Source)

Key Findings

  • The study, conducted in Oklahoma, Texas, and Louisiana, compared hybrid sweetgum clones to native sweetgum half-sibs
  • Hybrid sweetgum clones had higher wood specific gravity (0.49 vs. 0.46 g/cm³), which improves energy content and structural properties
  • Despite less fertilizer, hybrid sweetgum clones showed superior growth, with greater standing green stem biomass at 8.5 years (73.3 vs. 51.9 Mg/ha)
The increasing demand for bioenergy has driven the exploration of new sources of woody biomass, particularly from short-rotation woody crops (SRWCs) grown on marginal lands. This approach minimizes the competition with croplands and promotes the sustainable supply of wood for global biomass markets. A recent study conducted by Oklahoma State University has focused on hybrid sweetgum (Liquidambar styraciflua) clones as a promising SRWC species for hardwood pulp and biofuel feedstock production on marginal sites[1]. Sweetgum is recognized for its potential in SRWC systems due to its rapid growth and adaptability to less fertile soils. The recent study aimed to compare the productivity and wood quality attributes of hybrid sweetgum clones (L. formosana x styraciflua) with improved native sweetgum half-sib families across 36 stands in Oklahoma, Texas, and Louisiana, U.S. The researchers assessed various parameters, including wood specific gravity, stand growth, and green biomass production. The findings revealed that hybrid sweetgum clones exhibited significantly higher wood specific gravity compared to the half-sibs (0.49 vs. 0.46 g/cm³). Wood specific gravity is an important attribute as it influences the energy content and structural properties of the biomass. Additionally, the hybrid clones showed less taper, necessitating the development of genotype-specific volume and biomass equations to accurately estimate their biomass yield. Despite receiving less fertilizer input on average, the hybrid sweetgum clones demonstrated superior growth performance. At 8.5 years of age, the hybrids had a greater standing green stem biomass than the half-sibs (LSMean of 73.3 vs. 51.9 Mg/ha). Furthermore, during the 2022 growing season, the hybrids exhibited higher green biomass growth compared to the half-sibs (LSMean of 15.8 vs. 11.4 Mg/ha/y). These results indicate that the hybrid sweetgum clones not only grow faster but also produce higher quality wood, which can enhance the productivity and profitability of hardwood SRWC plantings. This study builds on previous research that has highlighted the potential of SRWCs on marginal lands. For instance, earlier studies have shown that growing SRWCs on lands used to mitigate environmental liabilities, such as municipal wastewater and subsurface contamination, can achieve mean annual aboveground green biomass increments (MAIs) ranging from 2.4 to 21.3 Mg/ha/y, depending on species and management practices[2]. The current study's findings align with these earlier results, demonstrating that hybrid sweetgum clones can achieve high biomass yields even with less intensive management. Moreover, the study by Oklahoma State University addresses some of the economic challenges associated with SRWC systems. Previous research has indicated that high establishment and maintenance costs, coupled with low stumpage values, can hinder the economic feasibility of SRWC plantations[2]. However, the superior growth and wood quality of hybrid sweetgum clones suggest that these hybrids could improve the economic viability of SRWC systems by increasing biomass production and reducing input costs. In summary, the research conducted by Oklahoma State University provides compelling evidence that hybrid sweetgum clones offer significant advantages over native sweetgum half-sibs in terms of growth performance and wood quality. These findings support the potential of hybrid sweetgum as a viable SRWC species for bioenergy production on marginal lands, contributing to the sustainability and profitability of the bioenergy sector.

AgricultureEnvironmentPlant Science

References

Main Study

1) Productivity of hybrid sweetgum (Liquidambar formosana x styraciflua) plantations compared to native sweetgum (L. Styraciflua) in the Western Gulf Region of south-central U.S.

Published 27th June, 2024

https://doi.org/10.1007/s11056-024-10057-7

Related Studies

2) SRWC bioenergy productivity and economic feasibility on marginal lands.

https://doi.org/10.1016/j.jenvman.2015.05.025


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