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Kang, Hojeong,Chris Freeman,Seok-Soon Park 한국하천호수학회 2006 생태와 환경 Vol.39 No.4
A suite of extracellular enzyme activities involved in organic carbon decomposition were determined in three northern peatlands (a bog, a fen, and a swamp) over a 12 month period along with trace gas (CO2 and N2O) flux and DOC dynamics in the wetlands. The activities varied 0.008-0.066 μmole g-1 min-1, 0.003-0.021 μmole g-1 min-1, 0.003-0.016 μmole g-1 min-1, 0.004-0.047 μmole g-1 min-1, for β-glucosidase, cellobiohydrolase, β-xylosidase, and N-acetylglucosaminidase, respectively. In general, the activities were highest in the forested swamp followed by the fen and the bog. When the data from three wetlands are combined, the enzyme activities exhibited significant positive correlations with trace gas emission and available carbon.Further, the average activity of 4 enzymes explained about 20-40% of the variations of trace gas emssion and available carbon. The results indicate that enzymes related to the mineralization of organic carbon may play an important role in trace gas flux and DOC dynamics in northern peatlands. A suite of extracellular enzyme activities involved in organic carbon decomposition were determined in three northern peatlands (a bog, a fen, and a swamp) over a 12 month period along with trace gas (CO2 and N2O) flux and DOC dynamics in the wetlands. The activities varied 0.008-0.066 μmole g-1 min-1, 0.003-0.021 μmole g-1 min-1, 0.003-0.016 μmole g-1 min-1, 0.004-0.047 μmole g-1 min-1, for β-glucosidase, cellobiohydrolase, β-xylosidase, and N-acetylglucosaminidase, respectively. In general, the activities were highest in the forested swamp followed by the fen and the bog. When the data from three wetlands are combined, the enzyme activities exhibited significant positive correlations with trace gas emission and available carbon. Further, the average activity of 4 enzymes explained about 20-40% of the variations of trace gas emssion and available carbon. The results indicate that enzymes related to the mineralization of organic carbon may play an important role in trace gas flux and DOC dynamics in northern peatlands.
Variations of soil enzyme activities in a temperate forest soil
Kang, Hojeong,Kang, Sinkyu,Lee, Dowon Springer Japan 2009 Ecological research Vol.24 No.5
<P><B>Abstract</B></P><P>Soil enzyme activities (dehydrogenase, urease, phosphatase, and arylsulfatase) in a temperate forest soil were determined in relation to landscape position and seasons. Overstory of the area is dominated by <I>Quercus mongolica</I>, <I>Kalopanax pictus</I>, <I>Carpicus cordata</I>, and <I>Acer pseudo‐sieboldianum</I>. The activities were measured in three patches, namely a north‐facing backslope, a ridge, and a south‐facing backslope in autumn and spring over 2 years. In addition, spatially more detailed analysis for phosphatase was conducted before and after litterfall production in six patches. Dehydrogenase, urease, phosphatase, and arylsulfatase activities varied 1.8–18.5 μg INT‐formazan g<SUP>−1</SUP> h<SUP>−1</SUP>, 45.4–347.0 μg NH<SUB>4</SUB><SUP>+</SUP> g<SUP>−1</SUP> h<SUP>−1</SUP>, 0.9–4.5 mmol pNP g<SUP>−1</SUP> h<SUP>−1</SUP>, and 0.7–2.6 mmol pNP g<SUP>−1</SUP> h<SUP>−1</SUP>, respectively. In general, higher enzyme activities were found in the northern aspect than in the southern aspect. This variation appears to be related to differences in chemical properties (e.g., Fe, Al, and Mg) of soil as well as distribution of leaf litter. Two patterns were discernible in relation to seasonal variations. Dehydrogenase and urease exhibited a positive correlation with mean air temperature, suggesting that temperature would be a major controlling variable for those enzymes. In contrast, higher activities were detected in autumn for phosphatase and arylsulfatase activities, which appeared to be closely related to litter production and distribution. Overall results of this study indicate that soil enzyme activities in a forest floor are influenced by several variables such as temperature, nutrient availability, and input of leaf litter, which are closely related to landscape position.</P>
Inhibition of Extracellular Enzyme Activities in a Forest Soil by Additions of Inorganic Nitrogen
Kang, Hojeong,Lee, Dowon Taylor Francis 2005 Communications in soil science and plant analysis Vol.36 No.15
<P>Forest ecosystems are known to be nitrogen (N) limited, and productivity often increases with N additions. However, recent studies have suggested that additions of excessive N through atmospheric deposition may affect soil processes adversely. In this study, we conducted a laboratory‐based manipulation experiment to reveal the effects of N additions on extracellular enzyme activities in a temperate forest soil. Three different levels of N additions (water‐only control, low N addition, and high N addition) were applied to soil columns (2.5‐cm diameter×12 cm height) over 4 weeks. Overall, the additions of N decreased specific activities (enzyme activity per log bacterial cell number) of urease, glutaminase, phosphatase, and arylsulfatase significantly. However, dehydrogenase activity was increased with the high N addition. The results suggest that N deposition may impede nutrient cycling, particularly mineralization of organic nutrients. In addition, this enzyme inhibition may be one of the mechanisms for N retention observed in forest floors.</P>
강호정(Hojeong Kang) 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11
전지구적 탄소 순환에서 토양의 호흡량이 차지하는 부분 (60 Pg)은 인간활동으로 배출되는 양 (약 11 Pg) 보다 훨씬 많은 부분을 차지하고 있다. 이 반응은 토양 내 미생물에 의해서 매개되고 있고, 이 반응에 대한 조절인자들이 널리 알려져 있다. 예를 들어, 온도, 수분이 토양 미생물의 활성도와 이로 인해 배출되는 CO₂ 양을 결정짓는 것으로 알려져 있다. 그러나 이 반응을 직접 매개하고 있는 미생물의 군집구조와 활성도에 대한 정보는 여전히 부족한 상황이다. 본 논문에서는 CO₂, 와 CH₄ 등의 온난화 기체 동태에 관여하는 다양한 미생물의 군집구조와 풍부도의 정보가 실제 생태계에서 발생 소멸되는 기체들 조절에 어떻게 관여하고 있는지에 대한 국내외 연구 결과를 소개하고자 한다. 특히 연안의 침입성 식물, 산림에서 간벌, 양식업 확장 등이 관련 미생물에 미치는 영향과 그로 인하여 배출되는 온난화기체 변동에 대한 실증적 결과에 대해 논의하고자 한다.
대기 질소강하물의 육상 생태계에 미치는 영향 및 국내 연구제안
강호정 한국환경생물학회 2001 환경생물 : 환경생물학회지 Vol.19 No.4
Effects of atmospheric nitrogen deposition on terrestrial ecosystems were reviewed and discussed in this paper. The amount of nitrogen deposition has increased rapidly in Europe, North America and Korea due to industrialization, increase in fossil fuel combustion(automobiles in particular), and intensive agricultural activities. Nitrogen input through such deposition may enhance primary productivity at early stage, but it could cause nitrogen saturation and hence induce deterioration of forests or disturbance of systems in the long term. Mechanisms of the deterioration of forests by nitrogen deposition include nutrient imbalance, soil acidification, and immobilization of toxic ions. In addition, nitrogen deposition may impede the decomposition rates of soil organic matter, and induce eutrophication in aquatic ecosystems by enhanced leaching of nitrate. Finally, I propose several topics in relation to nitrogen deposition, which warrant further studies in Korea.