• Journal of Ecology and Environment
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• v.31 no.3
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• pp.167-176
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• 2008

Atmospheric N deposition has far-reaching impacts on forest ecosystems, including on-site impacts such as soil acidification, fertilization, and nutrient imbalances, and off-site environmental impacts such as nitrate leaching and nitrous oxide emission. Although chronic N deposition has been believed to lead to forest N saturation, recent evidence suggests that N retention capacity, particularly in the forest floor, can be surprisingly high even under high N deposition. This review aims to provide an overview of N retention processes in the forest floor and the implications of changing C-N interactions for C sequestration. The fate of available N in forest soils has been explained by the competitive balance between tree roots, soil heterotrophs, and nitrifiers. However, high rates of N retention have been observed in numerous N addition experiments without noticeable increases in tree growth and soil respiration. Alternative hypotheses have been proposed to explain the gap between the input and loss of N in N-enriched, C-limited systems, including abiotic immobilization and mycorrhizal assimilation, both of which do not require additional C sources to incorporate N in soil N pools. Different fates of N in the forest floor have different implications for C sequestration. N-induced tree growth can enhance C accumulation in tree biomass as observed across temperate regions. C loss from forests can amount to or outweigh C gain in N-saturated, declining forests, while another type of 'C-N decoupling' can have positive or neutral effects on soil C sequestration through hampered organic matter decomposition or abiotic N immobilization, respectively.

• The Korean Journal of Ecology
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• v.18 no.1
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• pp.147-156
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• 1995

Restoration of ecosystems degraded by heavy metal pollution can be accomplished by soil amendment and selection and utilization of plants tolerant to heavy metals. Two former zinc mine sites, Sambo Mine in Hwasung, Kyonggi-do and the Second Yonhwa Mine in Samchuk, Kangwon-do, were selected for collection of plant samples and for determination of heavy metal tolerant species. Dominant species on mine waste deposits in Hwasung site were Panicum bisulcatum and Echinoch/oa crus-galli, while those in Samchuk site were Aster yomena, Setaria viridis, Artemisia lavandulaefolia and Oenothera odorata. Mean contents of zinc, lead and cadmium in Hwasung soil were 103, 117 and 1 ppm, respectively, while those in Samchuk soil were 23, 6 and 4 ppm, respectively, Zinc contents were higher in Echinochloa crus-galli from Hwasung and in Artemisia lavandulaefolia from Samchuk, while lead contents were higher in Panicum bisulcatum and Echinochloa crus-galli from Hwasung and Lactuca sonchiJolia and Pinus densiJolia from Samchuk. Plant species with higher cadmium contents were Panicum bisulcatum and Lactuca sonchiJolia. Comparison of metal contents between roots and shoots showed that Echinochloa crus-galli was a zinc accumulator, while Panicum bisulcatum, Persicaria hydroPiPer, Pinus densiJlora and Lactuca sonchiJolia were zinc excluders. In addition, Panicum bisulcatum and Persicaria hydroPiPer were proved to be lead excluders. When both heavy metal contents in plant tissues and biomass of individual plants are considered, it can be concluded that Echinochloa crus-galli and Panicum bisulcatum from Hwasung and Artemisia lavandulaefolia and Aster yomena are heavy metal absorbing plants. The effect of heavy metals on seed germination showed that Artemisia princeps var. orientalis had higher germination rates, but no significant difference in concomitant decrease of germination rates among the species investigated were found by increasing heavy metal contents.

• Ocean and Polar Research
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• v.43 no.1
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• pp.31-43
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• 2021

To understand the temporal variation of prokaryotic communities in a temperate coastal area, prokaryotic abundance, activity, and community composition were investigated every week for over a year at a coastal monitoring station of Yeong-do, Busan. The prokaryotic abundances fluctuated about 10 times, ranging from 2.0 to 20.1 × 10⁵ cells mL^-1 and tended to be high in spring when phytoplankton bloom occurred. The prokaryotic thymidine incorporation rates (TTI) varied in a low range between 0.2 and 11.5 pmol L^-1 h^-1 in winter. However, in summer, TTI were increased up to a range of 8.3 to 17.4 pmol L^-1 h^-1, showing an increasing pattern in summer. During the study period, Alphaproteobacteria was the most dominant class for most of the year, followed by Flavobacteria. While the seasonal variation of prokaryotic composition was not apparent at the class level, many prokaryotic species showed a distinct temporal or seasonal variation for the year. In the coastal site, prokaryotic biomass and activity did not show significant correlations with temperature and chlorophyll-a, which are well known to regulate prokaryotic growth in marine environments, suggesting that the study area may be affected by diverse sources of organic matter for their growth.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1095-1102
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• 2011

The effect of mixed cultivation with green manure crops and liquid pig manure on rice growth was investigated. Field experiment in site 1 (Astragalus sinicus L.) and site 2 (Lolium multiflorum Lam.) were designed with control (non-green manure crop), PLM 100 (non-green manure crop + liquid pig manure 100%), A(L)PLM 0 (green manure crop + PLM 0%), A(L)PLM 50 (green manure crop + PLM 50%), A(L)PLM 75 (green manure crop + PLM 75%), and A(L)PLM 100 (green manure crop + PLM 100%). The results of 1,000 grain in rice plant were in the order of APLM 100 ${\geqq}$ APLM 75 ${\fallingdotseq}$ PLM 100 ${\fallingdotseq}$ APLM 0 ${\fallingdotseq}$ APLM 50 ${\fallingdotseq}$ control for site 1 and LPLM 100 ${\geqq}$ LPLM 75 = LPLM 50 = PLM 100 ${\geqq}$ LPLM 0 ${\fallingdotseq}$ control for site 2. The yields of rice in site 1 and site 2 were $636kg\;10a^{-1}$ (increasing yield 10%) for APLM 100 and $775kg\;10a^{-1}$ (increasing yield 12%) for LPLM 100, respectively.

• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.294-302
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• 2016

This study was conducted to evaluate aboveground tree biomass and nutrient (C, N, P, K, Ca, and Mg) response of tree components by high (1,933 trees $ha^{-1}$) and low (1,200 tree $ha^{-1}$) stand densities in a 27-year-old Quercus glauca plantation. The study site was located in Goseong county, Gyeongsangnam-do, southern Korea. Total 12 trees (6 high and 6 low stand densities) were cut to develop allometric equations and to measure nutrient concentration of tree components. Stand density-specific allometric equations in the high and low stand densities were significant (P < 0.05) in tree components with diameter at breast height (DBH). Also, generalized allometric equations could be applied to estimate tree biomass regardless of the difference of stand density because of no significant effect on slope of stand density-specific allometric equations. Aboveground tree biomass estimated by the allometric equations was significantly higher in the high stand density (177 Mg $ha^{-1}$) than in the low stand density (114 Mg $ha^{-1}$). However, nutrient concentration of tree components was not significantly affected by the difference of stand density. Nutrient stocks in tree components were not significantly between the high stand density and the low stand density, except for the N and P stocks of stem wood. These results indicate that aboveground tree biomass could be significantly affected by stand density, but nutrient concentration among the tree components was not affected by the difference of stand density in a Quercus glauca plantation.

• Journal of Ecology and Environment
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• v.35 no.3
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• pp.235-242
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• 2012

Mikania micrantha, a neo-tropical vine, is spreading rapidly in the tropical part of Nepal and is now threatening the rural ecosystem including biodiversity and rural livelihoods. However, no attempt has been made to control the spread of M. micrantha. As a result, the vines are spreading freely and rapidly. After a thorough literature review and assessment of forest management practices, we proposed a manual cutting method, as it suits the Nepalese situation for several reasons: required labor is readily available, as local communities are managing forest patches, and the method does not have any potential adverse effects on non-target native species. Experimental plots were laid out in August 2011 to examine the effectiveness of manual cutting. Two different site types based on canopy coverage were selected and divided into three blocks based on cutting strategy. Four treatments were assigned across the experimental plots following a complete block design. We harvested above-ground biomass according to the assigned treatment. The results suggested that there should be at least two consecutive cuttings within a 3-week interval before flowering, and that three consecutive cuttings resulted in 91% mortality of the vines. In addition, cutting promoted regeneration of native plant species. Employing regular cutting operations can modify understory shade enhancing regeneration of native species, which is a desirable condition to constrain proliferation of M. micrantha. Periodic cuttings reduced the competitiveness of M. micrantha regardless of canopy openness, but native ground cover should be retained.

• The Korean Journal of Malacology
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• v.9 no.2
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• pp.16-22
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• 1993

Contamination of heavy metals in water and sediments along Mangyeong Gang(river) has reached up to critical level The object of the study is to elucidate somed molluscs which inhabit along the river on respect to the modulatory role in reducing the pollution. For the purpose, molluscs which are common in numbers and biomass in the area were collected, and Cadmim(Cd) was subjected as a reference metal in the experiment. The corresponding species were; Cipango;aludina chinensis (muddy snail) and Scapharca subcrenata (seashell). As methods, sample species were kept in laboratory under the natural condition as possible. Soil were brought from the site of the collection, dried autoclaved and wetted with ordinary water. It wad utilized as media to maintain the collected species in vitro all the way of the experiment. CdCI$^{2}$ was mixe in the medium according to experimental design. On the result obtained in the study, it is summarized that molluscs which inhabit along Mangyeong Gang(river)consume heavy mital-containing matters, so far Cd is concerned in the study. The amout of Cd concentration in tissues of the benthic natured invertebrates were dose and time related, and MT-Cd was also similar trend. Thus, Cd may eventually combine with low molecular protein forming metalloprotein, then reduce the toxicity of the heavy metal.

• Korean Journal of Organic Agriculture
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• v.3 no.1
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• pp.23-42
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• 1994

This paper studied earthworm populations in fields under practical cultivation in the Eastern Harzforeland (Germany). The examined sites differed insignificantly in their climatic and soil conditions. The examination was a comparison between a field and a narrow edge or meadow. A combination of Oktett method and handsortin was used. The five different habitates seven earthworm species were discoverd. The most frequently foundd were A. rosea, A. caliginosa, and A. chlorotica. There were clear differences in species between the habitates of each site. Generally the edge or the meadow contained one (Zoeberitz) or two (Zscherben) more species than the field. The composition of species differed between 1990 and 1992. In the dry Autumn of 1991 there were less species found at both sites. The occurance of earthworm species depends on the weather. Moisture influencing similiarity of abundance and bio-mass were recorded in three out of four habitates. Starting on a high level in Autumn 1990 the abundance as well as biomass decreased until Autumn 1991 and increased the following year. The number from 1990 were never reached again during the examination. One year of normal precipita-tion was not enough to return the population to the beginning level. Great differences in the number of earthworms between the compared habitats suggest that the edges and meadows are a potential immigration source into a field which is poor on earthworms. Structrues of distribution near the edge refer to a migration from a high populated edge into an almost empty field.

• Journal of Korean Society of Forest Science
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• v.106 no.4
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• pp.388-396
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• 2017

This study was carried out to determine effects of bamboo species on the distribution of nutrients in aboveground biomass of Phyllostachys bambusoides and Phyllostachys nigra var. nenosis, Damyanggun, Korea. The study site was established around 40-year-ago to produce bamboo culm and edible shoot production. Total 28 bamboos (14 P. bambusoides and 14 P. nigra var. nenosis) were cut to measure nutrient concentration of each bamboo component, such as culm, branches and leaf. Magnesium concentration in each bamboo component was significantly higher in the P. bambusoides than in the P. nigra var. nenosis. Nutrient concentrations except for calcium were significantly higher in the current-year-old bamboos than in the > 1-year-old bamboos. The nutrient concentration in leaf was generally highest in carbon, followed by potassium or nitrogen, phosphorus, calcium or magnesium. Total nutrient content in each bamboo component was significantly higher in the P. bambusoides than in the P. nigra var. nenosis. The nutrient content of bamboo biomass was the highest in carbon, followed by potassium, nitrogen, phosphorus, magnesium and calcium. The results indicate that P. bambusoides uptakes more nutrients compared with P. nigra var. nenosis during growth development.

• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.126-133
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• 1994

A Pseudomonas putida strain able to accumulate high amount of polyesters of medium-chain-length 3-hydroxyalkanoic acids ($PHA_{MCL)$) was isolated from soil in a landfill site using an enrichment technique. Culture condition of the isolated strain for polyester production in a one-step culture was optimized in a mineral-salts medium against pH and concentrations of ammonium sulfate, carbon source(e.g., octanoate), and phosphate. The optimal values for maximal cell growth and PHA accumulation were: pH; 7$\sim$8, $(NH_4)_2SO_4$; 8 mM, octanoate; 40 mM. The optimum temperature was in the range of $20\sim30^{\circ}C$, which was rather broader than in other bacteria. Cell growth was strongly inhibited by the phosphate limitation to less than 1 mM. An increase of phosphate concentration above 1 mM showed little effect on cell growth and polyester accumulation. When the strain was grown on octanoate under this optimized condition it produced 3.4 g dry biomass per liter and yielded 1.7 g PHA per liter amounting to 53 wt% of dry cells. The monomer units composing the polyester synthesized from octanoate were 3-hydroxyoctanoate (3HO), 3-hydroxycaproate (3HC), and 3-hydroxybutyrate (3HB) (85:13:2, mole ratio). Other low linear $C_3\simC_{10}$ monocarboxylic acids were also tested for polyester production.