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Seoul, South Korea

Choi W.I.L.,Korea forest Research Institute
Journal of Asia-Pacific Entomology | Year: 2011

Forest insect pests are one of the major disturbance factors in forest ecosystems and their outbreaks are expected to be more severe under the influence of global warming. Coleopterans are dominant among forest insects and their ecological functions include general detritivores, dead wood feeders, fungivores, herbivores, live wood feeders and predators. Ambrosia and bark beetles contribute to ecological succession of forests and, therefore, ecological functions of forests can be changed in response to their outbreaks. Mountain pine beetle (MPB) outbreaks are the most dramatic example of changes in the ecological functions of forest due to the outbreak of a forest insect pest altered by global warming. Composition of coleopteran species varies with latitude. However, composition of functional groups is consistent with latitude which indicates that resources available to beetles are consistent. In coleopteran communities, ambrosia and bark beetles can become dominant due to increases of dead or stressed trees due to the warming climate. This can also induce changes in the ecological functions of coleopterans, i.e. selective force to displace trees that have lower ecological fitness due to temperature increase. Therefore, recent increases in the density ambrosia and bark beetles offer a chance to study ecological processes in forests under the influence of global warming. © 2010. Source

The insecticidal activity of Piper nigrum fruit-derived piperidine alkaloid (piperine) and N-isobutylamide alkaloids (pellitorine, guineensine, pipercide and retrofractamide A) against female adults of Culex pipiens pallens and Aedes aegypti was examined. On the basis of 24-h LD50 values, the compound most toxic to female C. pipiens pallens was pellitorine (0.4μg) followed by guineensine (1.9μg), retrofractamide A (2.4μg) and pipercide (3.2μg). LD50 value of chlorpyrifos was 0.03g/. Against female A. aegypti, the insecticidal activity was more pronounced in pellitorine (0.17μg) than in retrofractamide A (1.5μg), guineensine (1.7μg), and pipercide (2.0μg). LD50 value of chlorpyrifos was 0.0014g. © 2012 Taylor & Francis Group, LLC. Source

Kim K.H.,Seoul National University | Kim J.-Y.,Seoul National University | Cho T.-S.,Korea forest Research Institute | Choi J.W.,Seoul National University
Bioresource Technology | Year: 2012

The aim of this study was to investigate the influence of pyrolysis temperature on the physicochemical properties and structure of biochar. Biochar was produced by fast pyrolysis of pitch pine (Pinus rigida) using a fluidized bed reactor at different pyrolysis temperatures (300, 400 and 500°C). The produced biochars were characterized by elemental analysis, Brunauer-Emmett-Teller (BET) surface area, particle size distributions, field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, solid-state 13C nuclear magnetic resonance (NMR) and X-ray diffraction (XRD). The yield of biochar decreased sharply from 60.7% to 14.4%, based on the oven-dried biomass weight, when the pyrolysis temperature rose from 300°C to 500°C. In addition, biochars were further carbonized with an increase in pyrolysis temperature and the char's remaining carbons were rearranged in stable form. The experimental results suggested that the biochar obtained at 400 and 500°C was composed of a highly ordered aromatic carbon structure. © 2012 Elsevier Ltd. Source

Yoon S.-Y.,Chungbuk National University | Han S.-H.,Korea forest Research Institute | Shin S.-J.,Chungbuk National University
Energy | Year: 2014

In acid hydrolysis of plant biomass, polysaccharides are converted to monosaccharides, which is basic raw material for biorefinery for fermentation based process. These monosaccharides, however, are not stable in acidic reaction medium, and are converted to organic acids via furans. Impact of hemicelluloses and lignin on acid hydrolysis of cellulose was investigated to focus on monosaccharide production with different degrees of cellulose purity. Two-step concentrated sulphuric acid process was applied to biomass for monosaccharide conversion. Kinetics of cellulose hydrolysis was analysed using 1H NMR spectroscopy. Higher reaction temperature in secondary hydrolysis caused severe degradation of the monosaccharides. In pure and holocellulose, further reaction of glucose in acidic reaction medium produced formic acid and levulinic acid. However, lignocellulosic biomass generated much less formic acid and levulinic acid under the same reaction condition. Humin (or pseudo-lignin) was also formed by the condensation of lignin and furans from monosaccharides in acidic reaction condition. Thus, the fermentation inhibitors, furans and formic acid, were generated in low quantities by lignocellulosic biomass than by delignified biomass such as pure cellulose or holocellulose. © 2014 Elsevier Ltd. Source

Kwon T.-S.,Korea forest Research Institute
Journal of Asia-Pacific Biodiversity | Year: 2014

Based on data of ants that were surveyed by the same method in the Gwangneung forest in 1993 and 2009, influences of climate changes on ant fauna were examined. If temperature in a region is lower than the optimum temperature, then the occurrence of the species increase as temperature rises; and vice versa. As temperature rises, it will be more advantageous to the species with high optimum temperature than the species with low optimum temperature. The optimum temperature, therefore, will have a linear relation with change of occurrence. In this study, two hypotheses were examined. Although significant difference was not found, the decrease expected group (with lower optimum temperature) decreased more in occurrence compared with the increase expected group (with higher optimum temperature). A highland dominant species, Myrmica kotokui, occurred in 1993 but did not occur in 2009. Comparison of ant fauna between 1993 and 2009 indicate a possibility of influence of climatic warming, but this finding was not proved statistically. Copyright © 2014 National Science Museum of Korea (NSMK) and Korea National Arboretum (KNA). Source

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