• Korean Journal of Medicinal Crop Science
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• v.11 no.4
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• pp.259-263
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• 2003

This study was carried out to get basic information about the morphological and production characteristics of fennel populations different origin under different ecological conditions in Hungary. The Korean population can be registered as a medium high genotype and showed a more accelerated growth characters than Hungarian taxon and the two populations have a medium homogeneity $(CV\;=\;4{\sim}22%)$. In the second year plant height in Hungarian taxon was significantly higher than that of the Korean population. The shooting dynamic of individual plants might be heterogeneous in both taxa and the Korean population was not only shorter in the height but had also less shoots by 16% than the Hungarian one. The Hungarian taxon exceeded the umbel size and numbers to the Korean one (by 3.62 cm in the average) and the variability in the populations was high $(CV\;=\;29{\sim}49%)$. Seed size was proved to be also a discriminative feature between the examined taxa. With small deviations (CV < 2) the Hungarian population produced seeds longer by 38%. Homogeneity in the populations was dependent more on the vegetation years and on the characteristics measured but less on the origins, respectively.

• Journal of Ecology and Environment
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• v.44 no.4
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• pp.264-274
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• 2020

Background: Climate change has altered the various ecosystem processes including forest ecosystem in Himalayan region. Although the high mountain natural forests including treelines in the Himalayan region are mainly reported to be temperature sensitive, the temperature-related water stress in an important growth-limiting factor for middle elevation mountains. And there are very few evidences on growth performance of planted forest in changing climate in the Himalayan region. A dendrochronological study was carried out to verify and record the impact of warming temperature tree growth by using the tree cores of Pinus roxburghii from Batase village of Dhulikhel in Central Nepal with sub-tropical climatic zone. For this total, 29 tree cores from 25 trees of P. roxburghii were measured and analyzed. Result: A 44-year long tree ring width chronology was constructed from the cores. The result showed that the radial growth of P. roxburghii was positively correlated with pre-monsoon (April) rainfall, although the correlation was not significant and negatively correlated with summer rainfall. The strongest negative correlation was found between radial growth and rainfall of June followed by the rainfall of January. Also, the radial growth showed significant positive correlation with that previous year August mean temperature and maximum temperature, and significant negative correlation between radial growth and maximum temperature (Tmax) of May and of spring season (March-May), indicating moisture as the key factor for radial growth. Despite the overall positive trend in the basal area increment (BAI), we have found the abrupt decline between 1995 and 2005 AD. Conclusion: The results indicated that chir pine planted population was moisture sensitive, and the negative impact of higher temperature during early growth season (March-May) was clearly seen on the radial growth. We emphasize that the forest would experience further moisture stress if the trend of warming temperatures continues. The unusual decreasing BAI trend might be associated with forest management processes including resin collection and other disturbances. Our results showed that the planted pine forest stand is sub-healthy due to major human intervention at times. Further exploration of growth climate response from different climatic zones and management regimes is important to improve our understanding on the growth performance of mid-hill pine forests in Nepal.

• Journal of the Korean Geographical Society
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• v.49 no.4
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• pp.525-545
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• 2014

This study seeks to clarify the influence of the stage migration which has proceeded through generations, on the population growth of local cities in the case of Jeollabuk-do. For this, setting to baby boomer as parents generation and echo boomer as their children, this study traces each generation's birth, distribution and the process of selective migration using aggregate level data. And the stage migration is analyzed by O-D, divided into three regions in each; Jeollabuk-do rural areas, Jeollabuk-do cities and other provinces. The major findings of this study are as follows. First, it was estimated that the number of the baby boomer births in Jeollabuk-do rural areas was seven times more numerous than in cities. Second, both rural and urban born baby boomers overwhelmingly moved into other provinces, especially Seoul metropolitan area and metropolis in their selective migration processes. However, there was also migration stream from rural areas to cities in Jeollabuk-do and the amount of this stream was approximately equal to the amount of outflux from cities in Jeollabuk-do to other provinces. Third, due to baby boomers' stage migration, from rural to urban, echo boomers were born in cities more than in rural areas. Fourth, urban born echo boomers still have moved into other provinces just like their parents generation in selective migration process. But comparing with baby boomer, the number of echo boomers influx from rural areas to cities has decreased. Consequentially the population of echo boomer in Jeollabuk-do cities also has decreased. Finally, the stage migration has been a basic cause of the social growth of urban population, and also influenced on the natural growth, closely connected with migrants' life course, such as marriage, childbirth and rearing. Therefore, this study concludes that the stage migration through generations is one of the crucial factor to understand the population growth in local cities.

• The Korean Journal of Ecology
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• v.22 no.6
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• pp.355-361
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• 1999

Distribution of size class, population regeneration and changes in the population structure of Quercus mongolica were studied from 1994 to 1999 in Mt. Jumbong (128°27' E, 38° 04' N) of Mt. Sorak National Park and Biosphere Reserve in central Korea. Three 20m × 20m permanent quadrats were set up at the elevation of 900m. The vegetation of the study site was dominated by Quercus mongolica and Acer pseudosieboldianum, but little change was observed in the community structure from 1995 to 1999. Most mortality in the study site was observed in small trees of A. pseudosieboldianum and Tilia amurensis. Mean annual growth in dbh (diameter of breast height) of Q. mongolica for 4 years was only 0.09cm, and no ingrowth of saplings (dbh < 2.5cm) into tree class was observed during the study period. Among the 21 Q. mongolica trees studied in the permanent quadrats. all the smaller trees (dbh < 30cm) were established in 1920 ∼ 1950, while many bigger trees (with 40cm < dbh < 80cm) were established in 1750 ∼ 1800, indicating that its establishment was episodic. Distribution of dbh classes among Q. mongolica trees shows that smaller trees were poorly represented, and no saplings of Q. mongolica occurred in the permanent quadrats studied, indicating that currently Q. mongolica is not regenerating well in the study site. Total seed production of Q. mongolica in 1994 was estimated as 88 acorns per square meter in the study site. Rate of predation including caching of acorns was highest in 1994, then declined sharply thereafter. Most of the acorns which managed to survive in the first year were predated in the second year, and only 5% of the acorns produced in 1994 survived into the third year. No seeds produced in 1994 or seedlings germinated from them succeeded to survive to 5 years after seed production. However, seedling emergence rate and seedling survival were high in the early growing season in 1995. These results suggest that predation can be a significant factor in the regeneration of Q. mongolica. and that Q. mongolica is not regenerating well in Mt. Jumbong and needs large scale disturbances for its new recruitment.

• Journal of Aquaculture
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• v.11 no.1
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• pp.99-103
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• 1998

Artemia often observed as a co-existing organism in the mass culture tank of marine rotifer. The rotifer and Atremia are commonly used as food organisms in the marine fish larvae rearing. In this study, interspecific relation between the rotifer Brachionus rotundiformis (formely called S-type) and anostracan Artemia of the two developmental stages (0 and 19 day old after hatching) were investigated in the larboratory. The population growth of B. rotundiformis and one of the stage (nauplius or adult) of Artemia in mixed culture was compared with that of each single species culture. Culture period was 16 days. Every two days, the number of organisms in each species was counted and transferred to a fresh medium containing $7{\times}10^5$cells/ml of food Nannochloropsis oculata. Culture volume, temperature, salinity and photoperiod were set at 40ml, $25^{\circ}C.$, 22ppt and 24h all dark except to observation time, respectively. The rotifer population growth was greatly decreased by co-existence with Artemia. The coexisting Artemia suppressed the rotifer population growth due to it's high filtering speed for food (N. oculata). This study suggested that contamination by Artemia must be prevented for the stable rotifer production in the rotifer mass culture tank.

• Environmental Engineering Research
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• v.12 no.2
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• pp.37-45
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• 2007

Phytoremediation has been used effectively for the biodegradation of oil-based contaminants, including diesel, by the stimulation of soil microbes near plant roots (rhizosphere). However, the technique has rarely been assessed for itsinfluence on soil microbial properties such as population, community structure, and diversity. In this study, the removal efficiency and characteristics of rhizobacteria for phytoremediation of diesel-contaminated soils were assessed using barnyard grass (Echinochloa crusgalli). The concentration of spiked diesel for treatments was around $6000\;mg\;kg^{-1}$. Diesel removal efficiencies reached 100% in rhizosphere soils, 76% in planted bulk soils, and 62% in unplanted bulk soils after 3weeks stabilization and 2 months growth(control, no microbial activity: 32%). The highest populations of culturable soil bacteria ($5.89{\times}10^8$ per g soil) and culturable hydrocarbon-degraders($5.65{\times}10^6$ per g soil) were found in diesel-contaminated rhizosphere soil, also yielding the highest microbial dehydrogenase. This suggests that the populations of soil bacteria, including hydrocarbon-degraders, were significantly increased by a synergistic rhizosphere + diesel effect. The diesel treatment alone resulted in negative population growth. In addition, we investigated the bacterial community structures of each soil sample based on DGGE (Denaturing Gel Gradient Electrophoresis) band patterns. Bacterial community structure was most influenced by the presence of diesel contamination (76.92% dissimilarity to the control) and by a diesel + rhizosphere treatment (65.62% dissimilarity), and least influenced by the rhizosphere treatment alone (48.15% dissimilarity). Based on the number of distinct DGGE bands, the bacterial diversity decreased with diesel treatment, but kept constant in the rhizosphere treatment. The rhizosphere thus positively influenced bacterial population density in diesel-contaminated soil, resulting in high removal efficiency of diesel.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.112-120
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• 2008

A series of experiments were conducted to establish a marine ecotoxicological standard method using marine primary producers, Skeletonema costatum, Heterosigma akashiwo, Prorocentrum micans, Isochrysis galbana, Tetraselmis suecica as candidate test species. Marine diatom, S. costatum was selected as standard test species in terms of the ecological roles and international uses as test species. Test methods and test acceptability criteria are as follows; $72{\sim}96$ hr population growth inhibition $EC_{50}$ as endpoint. Static non-renewal method, and population growth rates over 0.04/hr in control as test acceptability criterium. S. costatum is widely distributed in the world ocean and used for standard species of marine toxicity test method by ISO (International Standardization Organization). Possible salinity ranges for this test method are $20{\sim}35\;psu$, and reproducibility and interlaboratory test results were consistent through the calibration tests. Sensitivity of the test method was comparable or better than other toxicity tests such as rotifer neonate mortality, bioluminescent bacterial inhibition, seaweed sporulation and sea urchin fertilization tests.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.4
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• pp.66-78
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• 2003

The effects of several factors such as heavy metals, living microorganims, high molecular conglomerator in sewage sludge were analysed. And the effects of the sewage sludges which were mixed with other organic waste such as paper mill sludge or night soil sludge upon the feeding rate and biomass of earthworm population were also estimated. The earthworm populations could not survive when newly produced sewage sludges were fed without any pretreatment. The contents of heavy metals were under the levels that could inhibit earthworm's growth. The living microorganisms and the high molecular conglomerator in the sewage sludge had no relations with ecotoxicological effects of sewage sludge upon the earthworm population. Sewage sludge which had been mixed with paper mill sludge and aged for more than 21 days showed no ecotoxicological effects on tiger worm(Eisenia fetida) population. And the feeding rate of earthworm population and the turnover rate of earthworm biomass were higher in those sewage sludges than in the sewage sludges pretreated by other ways.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.322-328
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• 2016

This study investigated the effects of temperature, salinity, and algal diet to find the optimal conditions for 5 days for the mass culture of the tropical tintinnid, Metacylis tropica. This tintinnid had a small, hyaline, and ovoid lorica. The oral diameter, length, and maximum width of the lorica were $36.7{\mu}m$, $49.5{\mu}m$, and $44.5{\mu}m$, respectively. In the temperature experiments, the highest maximum density and population growth rate were observed at $30^{\circ}C$ with 340.7 cells/mL and 1.1/day, respectively. Lower salinities adversely affected the population growth of M. tropica. The maximum density was observed at 33 ppt (840 cells/mL). In the diet experiments, M. tropica fed Isochrysis galbana showed the highest density (413 cells/mL) and population growth rate (1.2/day). As a result, M. tropica is appropriate as a potential prey organism for early fish larvae with smaller mouths because the tintinnid has a relatively small size compared to the rotifer. In addition, the conditions of $30^{\circ}C$, 33 ppt and supplying I. galbana would be effective in the cultivation of M. tropica.

• Korean Journal of Environmental Biology
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• v.20 no.3
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• pp.256-262
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• 2002

This research investigated experimentally on the population growth in the aquatic microcosm with the wastewater of plating factory. The purpose of this study was to evaluate the effect of culture conditions of the characteristic growth pattern of the examined species. Population of the system is consists of three organisms; Chlorella vulgaris as a producer, Cyclidium glaucoma as a consumer and Pseudomonas putida as a decomposer. The different growth patterns of each population are followed by surfactant type; Especially C. glaucoma was sensitive, Ch. uvlgaris was maintained population size stably even at high level of surfactant and p. putida was not significantly affected. After treatment of waste water from plating factory, it began to be affected at 1.0% solution treatment to Ch. vulgaris which the cell number was decreased prominently after 2 days, and C. glaucoma was disappeared at 2.5% solution treatment. P. putida was showed increasing pattern according to treatment concentration, at 2.5% solution and population size grew double. The result from current microcosm study indicates that this model system can be applied to environmental assessment method for various pollutants.