• Journal of Ecology and Environment
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• v.32 no.3
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• pp.145-148
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• 2009

To understand whether experience of cold season in reproductive behaviors in the adults of Amaurobius ferox, the paired adults of a female and a male were exposed under 'cold-treated environment' and 'not cold-treated environment', respectively. I investigated effects of the cold treatment on the brood production of A. ferox. In not cold treatment in which male-female pairs were formed in October at a temperature of $20^{\circ}C$ (${\pm}2^{\circ}C$) and continuously kept under not cold-treated environment, only 3 of 50 pairs successfully reproduced (reproduction was defined as the emergence of spiderlings). In cold treatment where individuals were kept in cold conditions for 3 months prior to pair formation, 57 out of 60 couples succeeded in reproducing. Females which did not experience the low temperature displayed strong aggressiveness toward males. This behavioral inhibition might the primary barrier to copulation of A. ferox that decrease following a period of low temperature. The reproductive inhibition might help the females to allocate the maximum amount of energy in a given environment to reaching the adult stage and to delay reproduction in unfavorable wintering conditions.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.142-159
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• 1996

Engineering of automated tools for the agro-food industries and the rural world activities have to pick up two challenges : to answer the immediate important problems related to the situation of these industries, and to imaging the tools that their professional will need next century. Creating or modifying automated tools in the next few will be made taking into account parameters either technical (environmental protection, health and safety), or social and economical (investment , employment). There will be a strong interaction with disciplines like ecology, medicine, ergonomy, psycho-sociology , etc. , The partners for such a research, tools manufactures and users, should have an early involvement in its content, in order to find rapidly the solution to the drastic problems they are meeting. On a longer term , during the next 20 years , there will be an important evolution of the rural space management and of the food processes. This will imply the emergence of new types of activities and know-how's , with lines of automated tools to be invented and developed , like : micro-system for organic localized tasks -mobile and adaptive equipments highly autonomous for natural space actions - device for perception , decision and control reproducing automatically the expert behaviors of human operators. Design of such automated tools need to overcome technological difficulties like the automation of the expert-decision process, or the management of complex design.

• Journal of Ecology and Environment
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• v.46 no.1
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• pp.8-17
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• 2022

Background: Parthenium hysterophorus L. (Asteraceae; hereafter Parthenium) is an invasive alien species of global significance because of its' negative ecological and socioeconomic impacts. This species is spreading rapidly from lowland Tarai to Middle Mountain regions in Nepal. In the present study, we analyzed the impacts of Parthenium on plant community composition including their soil seedbank in subtropical grasslands located in central Nepal. Data was collected in a 10 m long transects passing through areas of high (> 90% cover), medium (40%-60%) and low (< 10%) levels of Parthenium cover using a plot of 1 m². Altogether, we sampled 90 plots in 30 transects. Seedling emergence method was used to estimate soil seedbank density in the soil samples (0-10 cm depth) collected from the plots with high Parthenium cover. Results: There was no significant difference in the plant species richness at different levels of Parthenium invasion whereas there was a significant change in the species composition of above ground flora due to Parthenium invasion. There was also a significant difference in species composition between soil seedbank and aboveground flora in the highly invaded plots. Parthenium was the most dominant in soil seedbank, contributing 65% to the total soil seedbank. Conclusions: Our study suggests that Parthenium has considerable negative impact on the native grassland flora, and the dominance of Parthenium in the soil seedbank means there is a challenge for its management. It also suggests the need of monitoring the soil seedbank dynamics while managing Parthenium weed.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.654-663
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• 2019

Pollinators, which are important organisms in pollination ecology, have been highly valued for their economic contributions to crop production in the agricultural and biotechnology industries. As the production of over 70% of farm products, such as fruits, are mediated by pollinators, bees are important and useful insects to humans. However, pollinators are now seriously threatened with their numbers decreasing annually and their biodiversity being negatively affected by ongoing climate change, misuse of land, change of geographical features, and use of pesticides to increase agricultural production. Thus, surveys and analyses of the emergence and distribution of wild bees are important for conservation and management practices designed to help them continue to play their ecological and agricultural roles despite negative pressures, such as climate and topography changes. We surveyed pollinators, especially wild bees, at 51 research sites in South Korea every two to four weeks for two years from 2017 to 2018 using ez-Malaise traps and analyzed the temporal and spatial distribution of wild bees. The bees showed a normal temporal distribution that peaked between July and August. The bees' working period lasted until November. The spatial distribution of wild bees showed a significant correlation with latitude, and different bees were identified depending on the local habitat. No significant correlation was found for longitudinal distribution with regression analysis (p > 0.05), but this study identified locally specific wild bees. Although we could not predict significant distribution according to longitude, Further studies should be able to analyze the difference in the distribution of wild bees according to the climate, topography, and land-use patterns by humans. The results of this study provide basic information on pollinator distribution, which can be useful in agriculture and for the conservation and management of biodiversity in South Korean pollination ecology.

• Korean Journal of Environment and Ecology
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• v.27 no.2
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• pp.196-203
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• 2013

Butterfly communities were monitored to investigate the emergence pattern with line transect method at Wolchulsan National Park through May to October in 2012. Totally 1,151 individuals belong to 49 species were monitored through the study period. Libythea celtis was a dominant species with showing 357 individuals(31%) followed by Pseudozizeeria maha 96 individuals(8.3%), Mycalesis gotama 75 individuals(6.5%) and Ninois dryas 72 individuals(6.2%) respectively. Among the monitoring periods, highest individuals and species(516 individuals belong to 30 species) were found at June and showed a high abundance near reservoir region. Highest diversity was shown at August with a Shannon index of 2.75 while lowest at October(Shanon index 1.78) and total diversity index was 1.71. Dominance values(Simpson index) showed highest at June with a value of 0.40 while lowest at September with a value of 0.07 and averaged 0.12. Kungol and Seongjeon compose a high similarity habitats with a similarity value of 0.52 and it was 0.17 at Kungol and Youngsan, lowest cases. Reservoir banks played a important role for habitats of specific species. It can be considered that they provide an open space of glass land for butterfly population, which was deficient at mountain area.

• Korean Journal of Weed Science
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• v.15 no.1
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• pp.39-45
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• 1995

This experiment was carried out at Yeongnam Crop Experiment Station since 1992 to obtain basic information on ecology of weeds and weedy rice in direct-seeded rice fields. Annual grass weeds of Echinochloa sp., Leptochloa sp., Digitaria sp. and Setaria sp.(C4 plant) and weedy rice(C3 plant) were important species in direct seeded rice compared to transplanted rice field. Period of seedling emergence of barnyard grass was varied from 8 days to 20 days depending on seeding date while it was shorter 4 to 6 days than rice. Weed occurrence and the degree of yield loss were varied by cultivation method. In direct seeding method weeds increased 2 to 3 times compared to manual transplanting. The greatest yield loss was recorded in direct seeding(40 to 100%) followed by mechanical transplanting(25 to 35%) and hand transplanting(10 to 20%), in order. Double cropping of rice-barley was reduced weeds about 30% than rice single crop due to alleopathic effect of barley residue or stubble. Weedy rice(red rice) occurrence was closely related with seeding date and tillage methods. Early seeding and reduced tillage enhanced the growth of weedy rice.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.90-97
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• 2008

The aim of this research was to detect and observe delivering generation effects from $F_0$ generation exposed to 4-nonylphenol 4NP) to $F_1$ generation on Tigriopus japonicus. The nauplius survival rate of $F_1$ from $F_0$ exposed to low 4NP concentration was significantly lower than other concentrations. Among the developmental process, copepodite first emergence day (CE) and adult male first emergence day (ME) on $F_1$ were accelerated relatively high concentration conditions. The sex ratio of $F_1$ was different between control group and treatment groups for 1, 10 and $30{\mu}g\;L^{-1}$ 4NP. The fecundity of $F_1$ was not significantly affected (except, $0.1{\mu}g\;L^{-1}$ 4NP). When 4NP concentrations were increased, first brooding day (FB) of F 1 was generally delayed. The length, width, and biomass of $F_1$ adult female were smaller than control group. In addition, the width and biomass of adult male were narrower or smaller than control group.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.266-273
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• 2019

Heavy metal contamination in freshwater ecosystem has been receiving increased worldwide attention due to their direct or indirect effect on human health and aquatic organisms. In this study, we investigated biological effects such as survival rate, growth rate, emergence rate, sex ratio and mouthpart deformity of Chironomus plumosus. The survival rate of C. plumosus decreased with the increase in heavy metal concentration as well as exposure time after cadmium (Cd) or zinc (Zn) exposure. The growth rate decreased at days 4 and 7 after Cd exposure and significantly reduced at the relatively high concentration of $50mg\;L^{-1}$ Cd. The emergence rate was decreased at $50mg\;L^{-1}$ Cd and $100mg\;L^{-1}$ Zn. The sex ratio showed imbalance pattern at relatively low concentrations (0.5 and $2mg\;L^{-1}$ Cd) with high proportion of male and relatively high concentration ($100mg\;L^{-1}$ Zn) with high proportion of female (60%). In addition, mentum deformities were observed at high concentration of Cd and Zn. These results suggest that heavy metal exposure in aquatic ecosystem may affect biological and morphological responses, and aquatic midge C. plumosus is a potential indicator for assessment of environmental pollutant such as heavy metals.

• Korean Journal of Ecology and Environment
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• v.52 no.1
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• pp.13-20
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• 2019

Heavy metals resulted from the increase of human industrial activity are introduced into the environment through rainfall and wastewater, and have harmful effects on inhabitants. In this study, we investigated biological responses such as survival rate, growth rate, emergence rate and sex ratio, and morphological effects of mentum deformity in Chironomus plumosus, an indicator organism to evaluate pollutions on aquatic ecosystem. The survival rate of C. plumosus showed time- and dose-dependent decrease after chromium and copper exposures. Growth rate decreased at $4^{th}$ day after chromium exposure and significantly reduced at exposure to relatively high concentration (copper $1000mg\;L^{-1}$) for all exposure times. In addition, we observed that the emergence rate by exposure to copper $1000mg\;L^{-1}$ was significantly lower than that of the control group. The imbalance of sex ratios showed at relatively low concentrations (chromium 10 and $50mg\;L^{-1}$) with the high proportion of female and at the relative high concentration (copper $1000mg\;L^{-1}$) with the high proportion of male. Furthermore, the morphological mentum deformities of C. plumosus observed in the exposed group according to chromium and copper exposure. These results suggest that the heavy metal exposure in environment may influence biosynthetic and morphological stresses of benthic invertebrate C. plumosus, and aquatic midge C. plumosus are potential indicators for toxicity assessment of heavy metals such as chromium and copper.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.35-44
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• 2005

Microclimate of Gwangneung forest watershed is characterized by analyzing wind, radiation, profiles of air temperature and humidity, soil and bole temperature, precipitation and soil water content measured at and around the flux tower from April 2000 to September 2003. Mountain-valley wind was prevalent due to the topographic effect with dominant wind from east during daytime and relatively weak wind from west during nighttime. Air temperature reaches its peak in July-August whereas monthly-averaged incoming shortwave radiation shows its peak in May due to summer monsoon. Albedo ranges from 0.12 to 0.16 during the growing season. Monthly-averaged bole temperature is in phase with monthly- averaged air temperature which is consistently higher. Monthly-averaged soil temperature lags behind air temperature and becomes higher with leaf fall. With the emergence of leafage in April, maximum temperature level during midday shifts from the ground surface to the crown level of 15-20m in May. Profiles of water vapor pressure show a similar shift in May but the ground surface remains as the major source of water. Vapor pressure deficit is highest in spring and lowest in winter. Monthly averaged surface soil temperatures range from 0 to 20℃ with a maximum in August. Monthly averaged trunk temperatures of the dominant tree species range from -5.8 to 21.6℃ with their seasonal variation and the magnitudes similar to those of air temperature. Annual precipitation amount varies significantly from year to year, of which >60% is from July and August. Vertical profiles of soil moisture show different characteristics that may suggest an important role of lateral movement of soil water associated with rainfall events.