Woody Biomass Harvesting and Postharvest Management: Opportunities, Challenges, and Technological Advancements

Abstract

The growing demand for woody biomass as a renewable energy source has resulted in increased biomass production in the southeastern United States (US). This growth raises questions about the readiness and willingness of forest stakeholders in the US South to participate in this expanding market. Economic constraints and environmental concerns remain subjects of debate. A detailed examination of biomass harvest operations in the southeastern US is essential to understand their long-term viability and environmental sustainability. Therefore, this dissertation presents a comprehensive background on biomass harvesting operations and subsequently provides three studies focusing on the operational and environmental impacts of these operations in the southeastern US. Additionally, it provides a systematic review of global trends in harvest operations research, addressing questions related to research gaps, harvest methods, and study methodologies. The first study analyzed the characteristics, attitudes, and perceptions of forest producers and consumers in Alabama, Georgia, Florida, and Mississippi regarding biomass market conditions and future operational plans through Qualtrics online surveys. The second study presents a comparative analysis of erosion estimates, operational features, best management practices (BMP) implementation rates, and ground cover characteristics between 15 biomass and 15 conventional harvests in the Coastal Plain region of Alabama, Georgia, and Florida, with 5 biomass and 5 conventional harvests evaluated in each state. The third study provides an innovative approach for predicting soil erosion rate from timber harvest sites integrating high-resolution imagery, deep learning, and geographic information system (GIS). The fourth study presents a systematic review of global trends and the status of timber harvesting operation productivity, cost, and fuel consumption, and methodologies used for such studies.

In the first study, the primary motivations for harvesting biomass were identified as enhancing site aesthetics, generating additional revenue, and diversifying business operations. Major challenges included transportation distances averaging 84-140 km (one-way), limited local markets, and high equipment, labor, and production costs. Nonetheless, the study indicates strong potential for increased biomass harvesting, as most producers and consumers are willing to expand operations given more profitable options with improved logistics and higher market value. In the second study, results indicated that average erosion rates (Mg/ha/year) from roads (biomass=4.17, conventional=6.44), skid trails (biomass=2.15, conventional=3.73), decks (biomass=0.39, conventional=0.72), and stream crossings (biomass=1.53, conventional=5.31) were significantly higher in conventional harvest sites. In contrast, no significant differences in erosion rates were observed for the harvest areas (biomass=0.11, conventional=0.06) and SMZs (biomass=0.05, conventional=0.02). Additionally, the overall weighted average erosion rate (biomass=0.22, conventional=0.35) and BMP implementation rate (biomass=97.91%, conventional=92.70%) did not exhibit significant differences between the two types of harvest sites. This study concludes that with proper BMPs, biomass harvesting does not lead to more significant erosion or water quality issues than conventional harvesting. In the third study, Deeplab V3 architecture equipped with a ResNet-34 backbone was identified as the most accurate model for segmenting harvest site categories. The findings revealed that roads posed the highest erosion risk, followed by skid trails, loading decks, clear-cuts, and streamside management zones (SMZs). The average erosion rate for a harvest site was determined to be 0.78 tonnes/ha/year. This study demonstrated an alternative method for erosion estimation by integrating advanced technologies and further documenting CP values for various harvest categories. In the fourth study, the systematic review emphasizes the importance of fuel consumption in harvesting costs and its role in carbon emissions, highlighting the need for more research on fuel consumption and emissions from harvesting operations. Overall, this dissertation presents valuable information on the challenges and opportunities related to biomass supply and timber harvesting practices. It emphasizes the importance of increased stakeholder engagement and the utilization of advanced technological tools to promote sustainable and more efficient woody biomass harvesting practices.