• Journal of Korean Society of Forest Science
• /
• v.111 no.1
• /
• pp.136-149
• /
• 2022

In this study, the performance of a nonlinear mixed-effects (NLME) model used to estimate the stem taper of Pinus densiflora in Gangwon Province was compared with that of a nonlinear fixed-effects (NLFE) model using several performance measures. For the diameters of whole tree stems, the NLME model improved on the performance of the NLFE model by 26.4%, 42.9%, 43.1%, and 0.9% in terms of BIAS, MAB, RMSE, and FI, respectively. For the cross-section areas of whole tree stems, the NLME model improved on the performance of the NLFE model by 67.7%, 44.7%, 45.8%, and 1.0% in terms of BIAS, MAB, RMSE, and FI, respectively. Based on the analysis of 12 relative height classes of tree stems, stem taper estimation performance was also reasonably improved by the NLME model, which showed better MAB, RMSE, and FI at every relative height class compared with those of the NLFE model. In some classes, the NLFE model had better BIAS than the NLME model (stem diameter: 0.05, 0.2, 0.3, and 0.8; stem cross-section area: 0.05, 0.3, 0.5, 0.6, and 1.0). However, the NLME model enhanced the performance of stem diameter and cross-section area estimations at the lowest stem part (0.2 m from the ground). Improvements for stem diameter in terms of BIAS, MAB, RMSE, and FI were 84.2%, 69.8%, 68.7%, and 3.1%, respectively. For stem cross-section areas, the improvements in BIAS, MAB, RMSE, and FI were 98.5%, 70.1%, 68.7%, and 3.1%, respectively. The cross-section area at 0.2 m from the ground occupied 22.7% of total cross-section area. Improvements in estimation of cross-section area at the lowest stem part indicate that stem volume estimation performance could also be enhanced. Although NLME models are more difficult to fit than NLFE models, the use of NLME models as a standard method for the estimating the parameters of stem taper equations should be considered.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.1112-1116
• /
• 2009

The importance of securing water resources and their efficient management has attracted more attention recently due to water deficit. In water budget analysis, however, evapotranspiration (${\lambda}E$) has been approximated as the residual in the water balance equation or estimated from empirical equations and assumptions. To minimize the uncertainties in these estimates, it is necessary to directly measure ${\lambda}E$. In this study, using the eddy covariance technique, we have measured ${\lambda}E$ in a mixed forest in the Seolmacheon catchment in Korea from September 2007 to December 2008. During the growing season (May - July), ${\lambda}E$ in this mixed forest averaged about 2.2 mm $d^{-1}$, whereas it was on average 0.5 mm $d^{-1}$ during the non-growing season in winter. The annual total ${\lambda}E$ in 2008 was 581 mm $y^{-1}$, which is about 1/3 of the annual precipitation of 1997 mm. Despite the differences in the amount and frequency of precipitation, the accumulated ${\lambda}E$ during the overlapping period (i.e., September to December) for 2007 and 2008 was both ${\sim}$ 110 mm, showing virtually no difference. The omega factor, which is a measure of decoupling between forest and the atmosphere, was on average 0.5, indicating that the contributions of equilibrium ${\lambda}E$ and imposed ${\lambda}E$ to the total ${\lambda}E$ were about the same. The results suggest that ${\lambda}E$in this mixed forest was controlled by various factors such as net radiation, vapor pressure deficit, and canopy conductance. In this study, based on the direct measurements of ${\lambda}E$, we have quantified the relative contribution of ${\lambda}E$in the water balance of a mixed forest in the Seolmacheon catchment. In combination with runoff data, the information on ${\lambda}E$ would greatly enhance the reliability of water budget analysis in this catchment.

• Journal of Korea Water Resources Association
• /
• v.54 no.11
• /
• pp.875-889
• /
• 2021

This study compares and analyzes the Soil and Water Assessment Tool (SWAT) and Terra MODIS (Moderate Resolution Imaging Spectroradiometer) as coniferous, deciduous and mixed forest with Yongdam Dam upstream (904.4 km²). The hydrologic evaluation period was set to 10 years from 2010 to 2019, and the applicability of the 8-day MOD15A2 Leaf Area Index (LAI) data, 3 TDR (Time Domain Reflectometry) (GB, JC, CC), and 1 Flux Tower (DU) evaporation volume (YDD) data was simulated. As a result, the R² of coniferous forest, deciduous forest and mixed forest are 0.95, 0.89, 0.90, soil moisture and evaportranspiration stations R² were analyzed at 0.50 to 0.55 and 0.51, respectively, with R² at 0.74, RMSE 2.75 mm/day, NSE 0.70 and PBIAS 14.3% for Yongdam inflow. Based on the calibrated and validated watersheds, the annual average evaportranspiration was calculated as coniferous 469.7 mm, deciduous 501. mm and 511.5 mm mixed forest, total runoff were estimated at coniferous 909.8 mm, deciduous 860.6 mm and 864.2 mm mixed forest. In the case of annual average evaportranspiration, it was evaluated that deciduous were high, but in the case of streamflow, it was evaluated that coniferous were high. Unlike other hydrologic with similar patterns throughout the year, the average annual evapotranspiration was about 7% higher than coniferous due to the higher evapotranspiration of deciduous with high leaf area index in summer and fall. In addition, deciduous were 9% and 6% higher for surface runoff and lateral flow, but the groundwater of coniferous was 77% higher. Therefore, it was confirmed that the total runoff was in order of coniferous, mixed forest, and deciduous.

• Journal of Forest and Environmental Science
• /
• v.30 no.4
• /
• pp.362-369
• /
• 2014

This study investigated physical properties and combustion gas characteristics for 8 types of wood pellets (4 domestic and 4 imported products) distributed in the domestic market. Results showed that most pellet types were first-grade pellets in the wood pellet quality standards in Korea with the exception of 3 pellet types from K company (second-grade in mechanical durability), G company (off-grade in nitrogen content) and P company (second-grade in ash percentage). Mixed pellets which contained more lignin and sap content were higher in mechanical durability (%) than that of white pellets. From the combustion gas analysis results, NOx emitted from all pellets combustion was at acceptable levels for national emission standard of the Clean Air Conservation Act except for pellets from G company. In addition, CO levels from all types of wood pellets were acceptable except for pellets from D company and domestic pellets were higher CO levels than imported pellets. These results indicate the higher CO levels in domestic pellets due to the usage of forest thinning materials including logging debris which usually had the high content of bark.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.15 no.6
• /
• pp.43-52
• /
• 2012

For this paper, a study targeting 9 forest patches in Dangjin to suggest for the wild birds, was conducted. The correlation between the emergence of wild birds and the forest vegetation was analyzed, and the patterns of forest vegetation for the improvement of species diversity were suggested by classifying wild birds and foraging guild by the type of forest vegetation. As for the characteristics of the wild birds emerged, more species and bigger population appeared in the vegetation type of mixed stand forest where the natural deciduous broadleaf trees and evergreen needleleaf trees coexisted in the large scale vegetation area. Thus, it was known that the advent of summer migratory birds and resident birds were affected the most by forest patches and vegetation types. As for foraging guild, the larger the forest paches the more the species and the population of the wild birds inhabiting in shrubs and bushes.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.38 no.5 s.118
• /
• pp.38-46
• /
• 2006

Many researches for extensive uses of Hanji have been performed. With the advent of an information-oriented age, the development of Hanji which is printable has been considered as a new field of study. Since Hanji has many drawbacks in comparison with common printing papers, that is, rougher surface, huger absorption of ink and lower physical properties and printabilities. Improving the properties and printabilities of Hanji is therefore the most important work to deal with. This study was conducted to find out useful mixed agents for surface sizing suitable for printable Hanji. Four surface sizing agents (CMC, corn starch, PYA, AKD) were applied for mixture in this study. The physical properties of surface sized Hanji were measured. Results obtained were as follows. Based on designated agents according to concentration, each of the mixed agents was prepared. The kinds of mixture were corn starch (3%) and PVA (5%), corn starch (3%) and AKD (0.1%), corn starch (3%) and CMC (1%), AKD (0.1%) and CMC (1%), AKD (0.1%) and PVA (5%), CMC (1%) and PVA (5%). Each mixed surface sizing agents was included with these ratios (100:0, 90:10, 70:30, 50:50, 30:70, 10:90, 0:100) respectively. All the mixed agents improved the physical properties and printabilities of Hanji. Among them, mixed agent of CMC (1%) and corn starch (3%) with 90:10 ratio is superior to the others for not only smoothness but also ink printability. In view of the result achieved, it is regarded that it can be fit for using Hanji as a printing paper and turned out to be a good contribution to Hanji industry.

• Journal of Forest and Environmental Science
• /
• v.30 no.1
• /
• pp.133-144
• /
• 2014

This study was carried out to review the pattern of forest stand development for six Gangwondo Baekdudaegan Mountains which experienced different type and duration of intensive legal protection. Vegetation data from point sampling method were employed to classify community types by cluster analysis on the basis of the importance values of canopy tree species for the study areas. The names of classified communities were given by the composition of dominant tree species. The communities were also compared one another in terms of stand structure by species diversity index. The results indicated that National Parks (Seoraksan and Odaesan) had greater proportion of mixed mesophytic forest type which was supposed to progress further forest succession process so as to have more complex and diversified stand structure. On the other hand, ordinary forest areas (Seokbyeongsan and Deokhangsan) had greater proportion of the forest types which was dominatively composed of Quercus mongolica and Pinus densiflora. The forest types with large amount of these two species would tend to develop for relatively short period of time of 40-50 years after artificial disturbances. Hyangnobong of Natural Protection Area and Hambaeksan of Natural Ecosystem Conservation Area showed intermediate stand development pattern in between National Parks and ordinary forest areas. The period of intensive legal protection of the forest area was positively correlated with species diversity index (R=0.736), and noted that the forest which received intensive protection regulation for longer period tended to show more complex and diversified stand structure.

• Korean Journal of Agricultural Science
• /
• v.49 no.2
• /
• pp.317-330
• /
• 2022

Recently, the policy regarding climate change in Korea and overseas has been to promote the utilization of forest biomass to achieve net zero emissions. In addition, with the implementation of the unused forest biomass system in 2018, the size of the Korean market for manufacturing wood pellets and wood chips using unused forest biomass is rapidly expanding. Therefore, it is necessary to estimate the total amount of unused forest biomass that can be used as an energy source and to identify the capacity that can be continuously produced annually. In this study, we estimated the actual forest area that can be produced of logging residue and the potential amount of unused forest biomass resources based on GT (green ton). Using a forest functions classification map (1 : 25,000), 5th digital forest type map (1 : 25,000), and digital elevation model (DEM), the forest area with a slope of 30° or less and mountain ridges of 70% or less was estimated based on production forest and IV age class or more. The total forest area where unused forest biomass can be produced was estimated to be 1,453,047 ha. Based on GT, the total amount of unused forest biomass potential resources in Korea was estimated to be 117,741,436 tons. By forest type, coniferous forests were estimated to be 48,513,580 tons (41.2%), broad-leaved forests 27,419,391 tons (23.3%), and mixed forests 41,808,465 tons (35.5%). Data from this research analysis can be used as basic data to estimate commercial use of unused forest biomass.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2003.11a
• /
• pp.47-50
• /
• 2003

$CO_2$ concentration profile was measured to investigate whether $CO_2$ concentration at one level (i.e., eddy covariance measurement level) can be used to estimate storage term without significant uncertainty at broadleaf deciduous forest at Kwangneung experiment forest in Korea. Based on t-test with significance level of 5％, there was no statistical difference between storage term from one-level $CO_2$ concentration and one from $CO_2$ profile measurement. Storage term constitutes on average 5％ of half hourly net ecosystem exchange (NEE) even at unstable stability (i.e., well mixed condition), indicating that storage term should be considered even at daytime, which is sometimes neglected.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.18 no.1
• /
• pp.127-133
• /
• 2015

Interests in ecosystem services have increased and a number of attempts to perform a quantitative valuation on them have been undertaken. To classify the ecosystem types landcover classification maps are generally used. However, some forest types on landcover classification maps have a number of errors. The purpose of this study is to verify the forest types on the landcover map by using a variety of field survey data and to suggest an improved method for forest type classifications. Forest types are compared by overlaying the landcover classification map with the 4th forest type map, and then they are verified by using National Forest Inventory, 3rd National Ecosystem Survey and field survey data. Misclassifications of forest types are found on the forest on the forest type map and farm and other grassland on the landcover map. Some errors of forest types occur at Daegu, Busan and Ulsan metropolitan cities and Gangwon province. The results of accuracy in comprehensive classification show that deciduous forest is 76.1%; coniferous forest is 54.0%; and mixed forest is 22.2%. In order to increase the classification accuracy of forest types a number of remote sensing images during various time periods should be used and the survey period of NFI and the National Forest Inventory and National Ecosystem Survey should be consistent. Also, examining areas with wide forest patch should be prioritized during the field survey in order to decrease any errors.