Forest Products Laboratory

Abstract Over 90% of U.S. homes are wood-based, making the residential construction sector both a major consumer of wood products and an important carbon sink. Understanding its long-term dynamics is critical for economic planning and carbon mitigation. Current U.S. models typically apply an exponential decay function to estimate carbon stored in wood products. However, recent research suggests this may not accurately reflect the time dynamics of wood products in housing, which remain in use for extended periods before disposal. This study compares the projections of U.S. single-family, multifamily, and manufactured housing inventories and associated carbon stocks from 2022 to 2070 using the conventional exponential decay model and an alternative chi- squared decay model, combined with three half-live assumptions (short, base, and long). Results reveal substantial differences in projected outcomes: under exponential decay, U.S. housing inventory declines, depending on half-life assumption, by 3 to 19% relative to 2022 levels, while chi-squared decay shows reductions of 3 to 52%. In contrast, total carbon stocks in housing inventory increase in the exponential model with all three half-life assumptions (14% to 16% relative to 2022 levels) and the chi-squared decay model with base and long half-life assumptions (10 to 18%). However, they decrease slightly (1%) for the chi-squared decay model with the short half-life assumption. These findings highlight the housing sector’s role in carbon storage and calls for a need to empirically validate decay functions and half-life parameters using updated time series data to improve long-term projections of housing inventories and associated carbon stocks.

The growing adoption of forest certification reflects a global shift toward more sustainable forest management and trade. Yet, the trade impacts of certification remain uneven, shaped by how these voluntary standards interact with national legal and regulatory environments. This study explores the conditions under which forest certification influences wood product exports, with a particular attention to the concept of institutional complementarity, where private standards and public laws reinforce each other. Using an extended gravity model of bilateral trade, the analysis integrates certification data with indicators of forest laws and legality-focused trade regulations. The results suggest that certification is more likely to support export performance when implemented within countries that possess coherent legal frameworks and effective enforcement mechanisms. In contrast, weak institutional alignment may reduce the benefits of certification or even hinder trade. These findings highlight the importance of regulatory coherence in realizing the trade potential of sustainability initiatives and point to the need for more context-sensitive approaches that consider the institutional realities of both exporting and importing countries.

Cellulose nanocrystal (CNC) photonic composites exhibit vivid structural colors but suffer from an inherent brittleness. Here, we develop flexible photonic CNC nanocomposites through in situ hybridization of periodate-oxidized dialdehyde CNCs (DACNCs) that maintain the original structural color (λ = 447 nm) while enhancing mechanical properties. The key innovation lies in DACNC’s dual functionality: it integrates into the chiral nematic helical structure while remaining optically neutral, participating in the formation of the nanocomposite film without altering the structural color. Circular dichroism confirms the preserved left-handed chiral character, and polarized optical microscopy reveals maintained birefringent textures. With 20% DACNC loading, the composite achieves a more than 4.3-fold fracture strain increase (5.1% versus CNC’s 1.2%), a 2.9-fold tensile strength (from 18.4 to 53.0 MPa) increase, and an 18-fold toughness increase (0.09 to 1.68 MJ/m3) without compromising the photonic property. This unique compatibility enables efficient stress dissipation while perfectly conserving the photonic nanostructure. Our work establishes a novelty materials design paradigm in which mechanical reinforcement and structural color integrity are simultaneously achieved through functionally differentiated components.

Wood used above ground and exposed to moisture may be vulnerable to decay. The initiation and rate of decay are influenced by several factors, including substrate type, moisture and temperature. The design and geometry of wood components affect moisture dynamics and may therefore influence both the initiation and progression of decay. This study evaluated the impact of nine different design configurations on the durability of wood components in a field experiment conducted at three North America sites with distinct climates. The tested variables included specimen volume, the presence of impermeable surface coatings, and the arrangement of appressed boards. Significant effects on both decay initiation and severity were observed, with water-trapping features such as appressed boards and sealed surfaces associated with earlier onset and more extensive decay over a fixed period. The results suggest that longer service life may be achieved by avoiding design features that retain moisture or inhibit drying.

Abstract Pyrogenic organic matter (PyOM) produced during fires plays an important role in the global carbon (C) cycle due to its low microbial availability and resulting high persistence. However, PyOM can be combusted or chemically altered in subsequent fires. To explore the effect of subsequent fire on PyOM, we used a mass loss calorimeter to deliver realistic heat fluxes to jack pine ( Pinus banksiana Lamb.) PyOM produced at 350 °C, testing heat flux profiles (High, Low, and Control) and burial depths (Surface, 1 cm, and 5 cm) in a full-factorial design. We found that both variables significantly affected the C remaining after burns ( p < 0.05), with greater C losses at higher heat fluxes and shallower exposure depths. Consistent with our predictions, treatments with high heat exposure (HF High +Surface, HF High +1cm, HF Low +Surface) showed increases in pH and decreases in total dissolved organic carbon (DOC) and mineralized C after the subsequent fire. Counter to our predictions, treatments with intermediate heat exposure (HF High +5cm and HF Low +1cm) caused significant decreases in pH and increases in DOC, mineralized C, modelled decomposable C, and modelled C decomposition rate ( p < 0.05), compared to the unburned controls. These findings highlight that, despite its high persistence in fire-free conditions, PyOM is readily combusted and altered in subsequent fires, with important implications for changing fire regimes and the global C cycle. Synopsis Statement Subsequent fires not only consume PyOM produced in previous burns, but can also increase its susceptibility to microbial decomposition, which challenges the potential for PyOM to contribute to long-term carbon storage.

Abstract A more systematic, multiscale characterization of the mechanical properties of lignocellulosic materials, such as wood and bamboo, is needed so that manufacturers can better tailor their properties for specific end-uses. Nanoindentation was used to assess the mesoscale elastic modulus ( E S N I ${E}_{S}^{NI}$ ) and Meyer’s hardness ( H ) of secondary cell wall layers (SCWL) in Moso bamboo, and S 2 SCWL and compound corner middle lamella (CCML) in loblolly pine. The anisotropic SCWL was tested in both longitudinal and transverse directions. The effects of moisture content (MC) were studied by testing specimens conditioned between 1 % and 92 % relative humidity (RH). Both pine and bamboo SCWL exhibited many of the same features in their MC- and orientation-dependent E S N I ${E}_{S}^{NI}$ and H results, which suggested that the features were general characteristics of SCWL from different plants. A new transition in plasticity was observed around 2–4 % MC in which the SCWL transverse H had a sudden 20 % decrease. For comparison to literature plasticity S 2 SCWL uniaxial compression flow stress ( σ ) measurements made using micropillar compression testing, a H -derived uniaxial compression flow stress ( σ H ) was calculated using established methods. The σ H compared well to the literature σ , which supported that both H and σ can be used to similarly study plastic deformation mechanisms.

Chirpine (Pinus roxburghii), also known as longleaf Indian pine, is the most tapped pine species in several Asian countries, including Nepal, for its high resin yield. Resin tapping in Chirpine trees has been a longstanding practice in mid-hills of Nepal for the last several decades. This study aimed to evaluate the social impacts of resin tapping from Chirpine forests on the rural socio-ecological dynamics of Nepal’s mid-hills. Using a representative sample of 302 forest users from 20 community forest user groups in three far-western districts, we applied the structural equation modeling approach to examine both the positive and negative perceived effects of resin tapping on the rural livelihoods. While respondents acknowledged the positive impacts of resin tapping on local employment and community development activities, many respondents stressed the negative environmental outcomes, including increased fire incidents, water scarcity, and higher mortality of pine trees. Results suggest that rich and male respondents are less likely to realize the negative impacts of resin tapping, whereas a member of community forest user groups is more likely to view resin tapping favorably. Understanding the perspectives of forest users on resin tapping within evolving socio-ecological dynamics shaped by changing social, demographic, and economics factors is critical for ensuring the sustainability of Chirpine based human-nature interactions.