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This study investigates the impact of omitting short tree data on tree height estimation in conventional forest inventories, focusing on Pinus koraiensis plantations in South Korea. Twenty height-diameter models were tested on both datasets: the complete data and the short tree-free data. The models were divided into Group 1 (with two model parameters) and Group 2 (with three model parameters) to examine whether the omission of short tree data affects model performance based on the number of parameters. Results demonstrated that excluding short tree data led to significant overestimation of tree height in small diameter ranges, with Group 2 models showing greater sensitivity to the omission. This omission also caused substantial variations in model rankings between the Full and short tree-free datasets, leading to specification errors and suboptimal model selection. Despite the small sample size difference, half of the Group 2 models produced non-significant parameter estimates when fitted to the short tree-free data, underscoring the influence of sample distribution on statistical outcomes. While most models maintained consistent height-diameter relationships during extrapolation, some generated unrealistic results, including negative or excessively large tree height estimates and inverse relationships in small diameter ranges. These findings emphasize the necessity of including short trees in forest inventory samples to mitigate biases in tree height estimation, which is critical for accurate biomass and carbon stock assessments.

Poor bucking decisions in forest stands can result in underestimating the profitability of timber sales. This study focuses on Pinus densiflora, commonly known as a red pine in Korea, which has often been underutilized as pulp and chips, leading to reduced profit margins. This study aimed to improve bucking decisions for red pine by analyzing the potential values in different log types and the profitability of manufacturing lumber products compared to pulp chips. A log sawing simulation model was developed using dynamic programming. This study optimized sawing patterns and estimated net profits for varying log sizes within the lumber market in Korea. The findings reveal that manufacturing lumber products from 3.6 m and 2.7 m logs can yield net profits 861% and 723% higher, respectively, than producing pulp chips from 1.8 m logs. Notably, sawing 3.6 m logs resulted in an average net profit 24% higher than from 2.7 m logs. These results advocate for more strategic bucking decisions based on potential timber sale profits and the end-uses of logs, especially in trees with large diameters at breast height (DBH), which can produce high-quality logs and should be bucked into long sawlogs whenever possible. Additionally, the study emphasizes the importance of practicing timber cruise to appraise the stumpage value of forest stands more accurately, moving beyond mere volume estimation to include tree type and expected volume. By implementing these practices, timber sale profits and the overall value of forest stands in Korea can be significantly enhanced. This approach not only benefits the economic aspect of forestry but also encourages sustainable and efficient resource management.

South Korea’s successful reforestation efforts over the past 50 years have led to abundant forest resources. However, intensive reforestation during the 1970s and 1980s skewed the forests’ age distribution towards forest stands aged 30 years or older, which results in an unbalanced distribution of age-class, requiring redistribution with harvest and effective regeneration plans to produce a sustained yield of timber as well as long term ecological benefits. During this conversion process, variations in timber production can occur, causing economic and ecological risks if excessive. To prevent these likely risks, permissible levels of increase and decrease in timber production can be restricted in the planning phase. In determining the appropriate variation rate in timber production, it is necessary to understand the impacts of variation in timber production on forest management. This study performed a sensitivity analysis to evaluate the economic and ecological impacts of constraining the period-to-period variation in timber production. A multi-objective linear programming (MOLP) forest management planning model was utilized to study forests in Mt. Gari, South Korea. Nine management alternatives were set with different levels of variation rate in timber production and further constraints. The total volume and net present value (NPV) of timber production, carbon storage, and water storage were analyzed for each alternative. As timber production variation rates decreased, the amount of timber production increased and forest carbon storage decreased; furthermore, NPV diminished as variation constraints strengthened. These differences were mainly caused by selection of regeneration species according to the constraint on variation in timber production. If the variation rate was strictly restricted, the area of timber species with short rotation age increased during conversion period, in order to reduce the gap of timber production between periods. At the latter part of planning horizon, the area of broad-leaved trees was enlarged as the burden of adjusting age-class structure reduced. The appropriate variation rate in timber production was determined to be 30%, based on considerations regarding the economic and ecological impact of the variation on the forest.

Smart windows, capable of tailoring light transmission, can significantly reduce energy consumption in building services. While mechano-responsive windows activated by strains are promising candidates, they face long-lasting challenges in which the space for the light scatterer’s operation has to be enlarged along with the window size, undermining the practicality. Recent attempts to tackle this challenge inevitably generate side effects with compromised performance in light modulation. Here, we introduce a cuttlefish-inspired design to enable the closing and opening of pores within the 3D porous structure by through-thickness compression, offering opacity and transparency upon release and compression. By changing the activation mode from the conventional in-plane to through-thickness direction, the space requirement is intrinsically decoupled from the lateral size of the scatterer. Central to our design is the asymmetry of pore orientation in the 3D porous structure. These inclined pores against the normal direction increase the opaqueness upon release and improve light modulation sensitivity to compression, enabling transmittance regulation upon compression by an infinitesimal displacement of 50 μ m. This work establishes a milestone for smart window technologies and will drive advancements in the development of opto-electric devices. Strain-responsive smart windows represent a green technology for transparency control but demand large space to activate. Here, a new material structure activated by compression is proposed, yielding strong optical regulation with minute deformation