• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.512-518
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• 2015

Pine wilt disease (PWD) caused by pine wood nematode, Bursaphelenchus xylophilus, has become the most serious threat to pine trees in Korea. This study was subjected to investigate effective biological control agent against PWD. To select nematocidal bacteria against PWD, Bacillus licheniformis MH48 was selected among five bacteria due to its high nematocidal potential. B. licheniformis MH48 was tested for cell growth and protease activity to evaluate its nematicidal potential. In the B. licheniformis MH48, cell numbers were highest three days after incubation, while protease activity was highest after seven days. In the effect of different concentrations of B. licheniformis MH48 culture broth against B. xylophilus, 20% concentration of culture broth showed approximately 80% of pine wood nematode mortality compared to the control. Especially, pine wood nematode's cuticle layers were degraded two days after treatment of B. licheniformis MH48 culture broth. The present study suggests that B. licheniformis MH48 can be one of the potential biocontrol candidates against pine wood nematode due to its ability to produce protease.

• The Korean Journal of Ecology
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• v.21 no.4
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• pp.373-382
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• 1998

This paper describes the ecological structure and function of riparian zone, and their historical changes with land-use. The riparian zone consists of valley floor landform and riparian vegetation. The functions discussed are attenuation of sunlight energy, input of leaves and needles, contribution of woody debris to streams, and retention of flowing material out of transport. These primary functions directly or indirectly influence water and sediment qualities of streams, bars and floodplains, and thereby aquatic biota. Temporal changes in a hydrological system and riparian ecosystem were examined with reference to land-use conversin in order to understand the linkages between these two systems in Toikanbetsu River. The influences of channelization and land-use on discharge of suspended sediment and wetland vegetation was also investigated in Kushiro Marsh. These two examples suggested that the ecological functions of riparian zone have been degraded as flood control and reclamation works have expanded in the past twenty years The author proposes river restoration planning by preserving or creating landscape elements based on the concepts of sustaining physical and ecological linkages.

• Journal of Ecology and Environment
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• v.30 no.1
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• pp.87-96
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• 2007

After introducing various aspects of the National Ecological Observatory Network (NEON) being planned and established in the US, the author tries to suggest the future direction for the development of similar activities of the NEON to be carried out in the region of East Asia including Korea. A review was carried out in terms of the challenges, major questions, missions, developmental history, and some other specifics of the NEON design. It was further extended to the discussion of the issues for the regional construction of the Ecological Observatory Network (EON) in East Asia. The author hopes that this review could be used as a preliminary guide in ultimately promoting and advancing research, science and technology in conservation and preservation of ecosystems being degraded due to anthropogenic disturbances in the region of East Asia.

• Journal of Conservation Science
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• v.16 s.16
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• pp.110-118
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• 2004

In order to evaluate two-step treatment of PEG-freeze drying for highly-degraded waterlogged ash woods (Fraxinus PP.; ca. 5,700 BP), which were excavated from peat lands in western Korea, dimension stability was examined during 45 months after complete treatment. The samples pre-treated with PEG in water solution showed better dimensional stabilities than the ones with PEG in t-butanol(TBA) solution. It suggests that TBA reduced the flexibility of wood cells and overflying by TBA induced micro-checks during freeze drying. Micro-checks results in fragile wood structures and consequently, large shrinkage by moisture absorbances of high PEG contents during exposure in humid condition. The results suggest that PEG in water-solution treatment is better than PEG in t-butanol as pretreament for freeze drying of highly-degraded waterlogged ash woods.

• Journal of Ecology and Environment
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• v.48 no.3
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• pp.263-276
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• 2024

Background: Repeated and severe fires have led to a large investment in research directed towards recapturing the natural values of Indonesia's peatland forest resources. The aim of this study was to identify the patterns and trends in research on peatland restoration-related literature available on the Scopus database. Methods in this paper a bibliometric methodology, the Scopus database and VOSviewer were used explore the trends in the published peatland restoration literature in the period 1994-2021; the leading journals and most influential authors, affiliations, countries, documents and research themes were identified. Results: Three hundred and seventeen documents including 266 journal articles were identified. The leading journals based on numbers of articles published and citations were Restoration Ecology and Ecological Engineering. Authors affiliated to institutions in Canada and the United Kingdom were the most influential. Indonesia was the third most influential based on numbers of documents. The most influential article was "The underappreciated potential of peatlands in global climate change mitigation strategies" by Liefield J in Nature Communications with an annual average citation rate of 66/year. A keyword co-occurrence network identified nine main themes in peat restoration research. Conclusions: The findings of the study are used to outline the types of research in peat restoration now required to meet the outstanding and unmet challenges confronted in Indonesia. Three significant challenges have been identified: (1) anthropogenic, those that encompass issues related to community acceptance and participation in peatland restoration, (2) ecological, those associated with severely degraded peatlands, and (3) economic, the absence of secure funding to cover substantial costs.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.404-415
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• 2000

This paper describes several performances and nondestructive inspection for deterioration due to forest fires in overhead transmission lines. After discussing corrosion mechanism such as atmospheric and galvanic corrosion for aged ACSR conductors and its detection for them are presented. Through impedance analysis of a solenoid coil, it is shown that the eddy current sensor may be available to inspect severe fault or local corrosion. As the solenoid coil changes its impedance when the test conductor is inserted into the coil, it can be possible to measure deterioration degree caused by forest fires. Tensile strength, extension rate and sensor impedance are tested for some samples degraded by artificial fire. As increasing blazed period to some extent, the strength of aluminum strand begins to be reduced remarkably, while galvanized steel strand holds the similar strength to the initial value, despite of appearing a little loss of zinc layer. In general, it is shown that the sensor impedance would be increased while the tension load of conductor is reduced and the extension rate is contrarily increased. Therefore, the sensor output could exhibit the changes of mechanical performances, and would be used to detect such deterioration caused by forest fire in ACSR conductors built on the ridge of mountains. Finally, it was verified that the solenoid coil could be applicable to obtain any crucial inform for serious deterioration due to forest fires.

• Journal of the Korean Wood Science and Technology
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• v.37 no.6
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• pp.566-577
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• 2009

The modification of wood color occurs rapidly during the service period at indoor. It is crucial to investigate the characteristics of color change, chemical and microscopical modification of wood at indoor. Wood products made of Japanese cedar at different years were used for this work. The tests were performed in order to evaluate the degree of color change of wood surface, breakpoint of brightness from surface to inside of wood, chemical analysis with FT-IR, and microscopical characteristics using the LM and TEM. Surface color of cedar wood stored indoor were rapidly changed at early stage, particularly ${\Delta}a$ (yellow), and ${\Delta}b$ (red) values were steeply decreased for one year old indoor wood, ${\Delta}L$ (white) value was dropped until 5 years old indoor wood compared with control sample. Decrease of peaks related to polysaccharide and lignin was noticed, especially, lignin was severely degraded. Although degradation of cell wall limited only to surface layers of indoor wood, degradation pattern of indoor wood showed similar degradation pattern to natural weathering of wood during outdoor weathering or wood behavior under artificial UV irradiation.

• Journal of the Korean Wood Science and Technology
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• v.33 no.1 s.129
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• pp.77-86
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• 2005

In order to investigate the ability of log wood for oak mushroom production as a source of an alternative energy, both chemical and physical characteristics of log wood were investigated according to the cultivation periods. Also, both chemical and physical characteristics of material that treated by steam explosion were investigated to confirm the pretreatment effect by remaining enzyme as a control. The contents of ash, water-, alkali- and organic soluble extracts have been increased after the inoculation. It appeard that holocellulose contents substantially decreased and the contents of lignin as another main component of wood remained constant after the inoculation. However this result implied that indeed, a sufficient amount of lignin has been degraded paritially by enzymes of oak mushroom Lentinus edodes if we consider that the amount of holocelulose was substantially reduced. It also indicated that the degree of degradation gradually progressed but crystallinity decreased after the inoculation. The contents of water-, alkali- and organic soluble extracts have been increased by steam explosion. Holocellulose contents increased within narrow limits and lignin contents remained constant. However the contents of holocellulose and lignin have been decreased by steam explosion, considering that the amount of other extractives was relatively increased. The degree of crystallinity and lignin contents reduction by steam explosion was almost similar to the result obtained by increasing cultivation periods. According to the results, log woods for mushroom production have a potential as material for developing alternative energy.

• Journal of Korea Foresty Energy
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• v.17 no.1
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• pp.56-70
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• 1998

This study was carried out to investigate the structural characteristics of kraft lignin and the wood degrading characteristics, the productivity of ligninolytic enzymes and the enzymatic degradation of kraft lignin by white-rot fungi. To purify kraft lignin, precipitation of kraft pulping black liquors of pitch pine meal was done by titration with lN $H_{2}SO_{4}$ reaching to pH 2, and isolation of the precipitates done by centrifugation. The isolated precipitates from pitch pine were redissloved in lN NaOH, reprecipitated by titration with lN $H_{2}SO_{4}$, washed with deionized water, and kept ofr analysis after freeze drying. Fractionation of the precipitates in solution by successive extraction with $CH_{2}Cl_{2}$ and MeOH, and the fractionates were named SwKL, SwKL I, SwKL II, and SwKL III for pitch pine kraft lignin. The more molecular weights of kraft lignin increased, the less phenolic hydroxyl groups and the more aliphatic hydroxyl groups. Because as the molecular weights increased, the ratio of etherified guaiayl/syringyl(G/S ratio) and the percentage were increased. The spectra obtained by 13C NMR and FTIR assigned by comparing the chemical shifts of various signals with shifts of signals from autherized ones reported. The optimal growth temperature and pH of white-rot fungi in medium were $28^{\circ}C$ and 4.5-5.0, respectively. Especially, in temperature and pH range, and mycelial growth, the best white-rot fungus selected was Phanerochaete chrysosporium for biodegradation. For the degradation pathways, the ligninolytic fungus jcultivated with stationary culture using medium of 1% kraft lignin as a substrate for 3 weeks at $28^{\circ}C$. The weight loss of pitch pine kraft lignin was 15.8%. The degraded products extracted successively methoanol, 90% dioxane and diethyl ether. The ether solubles were analyzed by HPLC. Kraft lignin degradation was initiated in $\beta$-O-4 bonds of lignin by the laccase from Phanerochaete chrysosporium and the degraded compounds were produced from the cleavage of $C\alpha$-$C\beta$ linkages at the side chains by oxidation process. After $C\alpha$-$C\beta$ cleavage, $C\alpha$-Carbon was oxidized and changed into aldehyde and acidic compounds such as syringic acid, syringic aldehyde and vanilline. And the other compound as quinonemethide, coumarin, was analyzed. The structural characteristics of kraft lignin were composed of guaiacyl group substituted functional OHs, methoxyl, and carbonyl at C-3, -4, and -5 and these groups were combinated with $\alpha$ aryl ether, $\beta$ aryl ether and biphenyl. Kraft lignin degradation pathways by Phanerochaete chrysosporium were initially accomplished cleavage of $C\alpha$-$C\beta$ linkages and $C\alpha$ oxidation at the propyl side chains and finally cleavage of aromatic ring and oxidation of OHs.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.278-287
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• 2017

In this study, lignin was efficiently degraded via two-step catalytic cracking process and lignin-oil, char, and gas was produced as lignin degraded products. Three kinds of catalysts (MgO, CaO, and Pt/C) were used in first catalytic cracking step and the highest lignin-oil yield (76.2 wt%) was obtained in Pt/C catalyst with the smallest char formation (4.1 wt%). GC-MS/FID analysis revealed that 18 kinds of monomeric phenols existed in lignin-oil and sum of them was the highest in Pt/C condition (97.8 mg/g lignin). Meanwhile, relatively lower yield of monomeric phenols was produced in MgO and CaO condition because of their absorption on catalysts. Lignin-oil produced over Pt/C was introduced to second catalytic cracking process with porous Pd/activated carbon aerogel catalyst. From this process, four kinds of monomeric phenols such as 4-ethylguaiacol, 4-propylguaiacol, 4-ethylsyringol, 4-propylsyringol were selectively produced at 0.89 - 1.82 wt% level.