To provide a basis for the effective and efficient design of windbreak forests, wind tunnel tests were conducted to analyze the protection against wind afforded by the use of various species and various structures of planted trees. Various row-based planting structures were used in an attempt to find the most effective arrangement of a windbreak forest. Four types of structures were studied: a simple structure of coniferous trees (1, 2, or 3 rows of Pinus thunbergii), a simple structure of broadleaf trees (1, 2, or 3 rows of Quercus acutissima), mixed structure 1 (3 rows: P. thunbergii, Q. acutissima and P. thunbergii) and mixed structure 2 (3 rows: Q. acutissima, P. thunbergii and Q. acutissima). The testing materials were 3-year-old P. thunbergii and 8-year-old Q. acutissima. As the height of the testing part was 2.0 m, the height of trees was cut to make it 1.5 m based. The trees were fixed in a vase of 30 cm (Width) × 30 cm (Height). The experimental simulation model was designed 3meter (Width) × 2meter (Height) × 9 meter (Length). Putting porosity between trees aside, it was appropriate with the 7.5% of black ratio. All arrangements of P. thunbergii rows decreased the wind speed at every measurement point; especially, the 3-row structure of P. thunbergii showed a wind speed reduction of more than 15% greater than the two single-row structures studied. The wind speed reduction of P. thunbergii was maximized at a distance 1 m downwind from the last row, with wind speed increasing further downwind. Also, comparing the effect of decreasing wind speed according to the height in one-layered structure, middle-height marked the best decrease and lowered as it goes far from the middle-height. This can be explained with the cone-shaped water pipe. However, observing that the same phenomenon does not happen in three-layered structures, it was found that the difference due to different shapes of the water pipe can be offset by adding a row of plants. Therefore, using the alternating structure of coniferous, broadleaf, and coniferous rows would be a better choice, offering a similar effect with less risk of loss to disease and insects.
Wind barriers play a vital role in protecting saplings until maturity when planted as vegetative windbreak forests. Most previous studies have focused on the porosity of wind barriers, but no studies have simultaneously examined the effects of the porosity and inclination, despite the potential of the inclination to decrease wind speed. We tested three wind barrier cases in wind tunnel experiments: (1) Case A (porosity of 0% with inclinations (90°, 80°, and 70°)), (2) Case B (porosity of 25% with inclinations (90°, 80°, and 70°)), and (3) Case C (porosity of 50% with inclinations (90°, 80°, and 70°)). The vertical and horizontal wind velocities were measured at three vertical and seven horizontal points behind the barriers. The results demonstrated a statistically significant decrease in the correlation between the distance and mean wind velocity for all cases, with up to a six-fold wind protection effect. The wind barrier with 0% porosity and a 90° inclination provided the highest degree of wind protection. However, the wind protection range was limited downwind, and recirculation of wind flow could occur in the leeward direction, potentially damaging saplings. A wind barrier with 50% porosity and 70° inclination sufficiently decreased the wind velocity and prevented recirculation of wind flow, demonstrating that both porosity and inclination considerably impacted the wind protection effect by reducing wind velocity. Our findings offer novel insights into the influence of wind barriers with varying porosities and inclinations and can provide valuable guidance for constructing efficient windbreak forests.
The goal of the present study was to provide basic data for establishing climate change adaptation measures and to support appropriate forest management in Jeollabuk-do, Republic of Korea. An assessment of forest vulnerability to landslide caused by localized torrential rainfall was conducted for Jeollabuk-do, taking into consideration the local climate characteristics and the regional characteristics of the forest. CCGIS, a climate change adaptation software toolkit based on GIS, was used to carry out the vulnerability assessment of each city and county of Jeollabuk-do. To improve the assessment, locally specific variable weights were prepared, based on the results of a Delphi investigation targeting public forestry staff in Jeollabuk-do. The regionally specific weight was greatest for the variable of climate exposure, followed by sensitivity and adaptability. According to the vulnerability assessment over the course of time, in most of the forest the vulnerability rating decreased from 2000s to 2020s, and later it decreased once again in all urban areas. The vulnerability of forests was predicted to be greatest in the 2050s. Hence, if the local government sets up an adaptation policy using this research data that assessed the landslide vulnerability of forest in Jeollabuk-do, Korea taking account of the characteristics of the local area, we consider that an effective policy can be established and forest management can incorporate measures to adapt to climate change.
In this study, we aimed to develop site index curves and a height growth model using forest data with the measured height, diameter at breast height (DBH), and age targeting a Larix kaempferi stand located on Mt. Deogyu in Muju, Jeollabuk-do. The site index estimation was calculated using Chapman-Richards equation. The coefficients were found to be α = 20.7837, β = 0.0566, γ = 1.6607, and MSE = 1.2034. The height growth model of the dominant trees depending on the DBH was determined to be α = 0.4872, β = 0.3687, and MSE = 1.8212 using the Petterson growth model. The Mean residual values for above two models were analyzed as 0.00004 and −0.00007, respectively. When comparing the skewness and kurtosis of the residual, the skewness values were 0.1659 and −0.1272, and the kurtosis values were −0.2310 and −0.5543. Therefore, the fitness was considered to be good because they were close to the normal distribution. The results of Shapiro-Wilk test showed P-values (0.77 for the height growth model and 0.62 for the height-DBH model) significantly higher than the alpha level of 0.05, and the residual form of the estimated values for the measured values showed uniform distribution indicating that the fitness of the two models was excellent.
30 June 2022 in Journal of Environmental Science International
Gastrodia elata has been a valuable medicinal resource in the East for approximately 3000 years. In South Korea, G. elata is cultivated in open-fields or greenhouses near residential areas. However, due to severe continuous damage, cultivation sites need to be frequently relocated, leading to a shortage of available cultivation areas. Alternatively, farmers are focusing on mountain cultivation. This study analyzed suitable cultivation sites for G. elata in mountainous areas using a geographic information system (GIS) and applied various classification methods to identify their characteristics and similarities. The analysis showed that the Natural Breaks (Jenks) classification method maximized the differences between grades, whereas the Quantile method reclassified the area of suitable sites to a relatively high proportion. In contrast, the Equal Interval method reclassified the areas of suitable and unsuitable sites to a lower proportion, whereas the Geometric Interval method best demonstrated extreme-temperature regions as unsuitable sites. Among the classification methods, the Natural Breaks (Jenks) and Geometric Interval methods yielded the most similar results. These findings provide critical methodological outcomes for G. elata cultivation and sustainable agriculture and forestry. Future empirical research and the application of climate change scenarios are necessary to enhance the sustainability of the G. elata cultivation industry.