Author ORCID Identifier

https://orcid.org/0009-0006-6838-8808

Semester

Summer

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Division of Forestry and Natural Resources

Committee Chair

Jingxin Wang

Committee Co-Chair

Levente Denes

Committee Member

Levente Denes

Committee Member

Zhichao Liu

Abstract

A life-cycle impact assessment of hardwood resources across the eastern United States was conducted based on the life-cycle inventory data for hardwood forest resource management and was integrated with the Forest Vegetation Simulator (FVS). This integration allowed for the analysis of forest carbon dynamics in the four subregions: northeast (NE), mid-Atlantic (MA), southeast (SE), and northcentral (NC). The system boundary was selected to be consistent with the A1 module (extraction and upstream production) required by an Environmental Product Declaration (EPD) for wood products. The results indicated that uneven-aged management (UA) yielded higher carbon stocks than even-aged management (EA) across all subregions. In contrast, clearcutting under EA resulted in higher carbon removal. Fuel consumption-related greenhouse gas (GHG) emissions for manual and mechanized harvesting systems for both management practices ranged between 9.13 and 12.15 kilograms of CO2 equivalent per cubic meter (kg CO2e/m3), with an average of 11 kg CO2e/m3 of hardwood timber harvested across all subregions. It was estimated that 63-187 megajoules (MJ) of energy were needed to produce 1 m3 of hardwood sawlogs. The extraction and loading processes contributed more to the total GHG emissions than the felling and processing within the system boundary. The study concluded that UA led to higher forest carbon and net carbon balance (excluding carbon stock) compared to EA in the eastern U.S. hardwood forests. Forest management practices should be determined based on the ecological goal of increasing forest carbon stock and the economic goal of maximizing timber production. The findings of this study have implications for policymakers and forest managers in mitigating climate change and enhancing carbon sequestration through sustainable forest management practices for timber production.

The Life Cycle Assessment (LCA) was used to assess the environmental impact of hardwood cross-laminated timber (CLT) production in the eastern United States. CLT is an emerging sustainable construction material with the potential to replace concrete. LCA has been widely applied to quantify the environmental impact of CLT materials and buildings. However, current research on CLT LCA mainly focuses on softwoods, lacking reports on hardwood CLT. Despite the less frequent utilization of hardwoods by CLT manufacturers, hardwood CLT is technically feasible and provides value-added uses for low-quality timber. This study developed a cradle-to-gate life cycle modeling framework for the production of hardwood CLT in the eastern United States to address this research gap. The framework integrates process-based modeling of log production, lumber production, and CLT production and explores the influences of hardwood species, supply chain network, and energy sources through sensitivity analysis. The global warming impact of producing 1 m3 of hardwood CLT ranged from 141.9 to 377.4 kilograms (kg) of carbon dioxide equivalent (CO2 eq). The results showed that to satisfy the manufacturing requirements of CLT, lumber production caused more energy consumption and emissions than CLT production. Compared to selecting low-density hardwood species and minimizing transportation distance, increasing the use of biomass energy can more effectively reduce the overall environmental impact. Furthermore, the amount of carbon stored in hardwood CLT exceeded the carbon emitted during its production, with a net carbon storage of 430.2 to 988.3 kg CO2 eq per m3. This study provides valuable insights for the development of EPDs for hardwood CLT and proposes improvement strategies to enhance the sustainability and market competitiveness of hardwood CLT.

Embargo Reason

Publication Pending

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Available for download on Thursday, July 31, 2025

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