• Korean journal of applied entomology
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• v.27 no.2
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• pp.81-86
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• 1988

Experiments were conducted to investigate the locational and ovipositional preferences of the single and mixed populations of the brown planthopper(BPH), Nilaparvata lugens (Stal), and the whitebacked planthopper(WBPH),Sogatella furcifera (Hovath), with the different popula-tion densities at seeding, max-tillering, booting and heading stages of rice variety seonam by대. The WBPH showed a locational preference for the upper portion while the BPH was observed to stay generally on the lower portion regardless of rice growth stages, population density-levels and the single or the mixed populations of two species. At seeding, max-tillerinf, boo-tring and heading stage, the preference for the lower portion of the rice plants was found to be slighty reduced with the lapse of time, respectively, from the single or the mixed popula-tions of both the species. Ovipositional lication of both the species was found not to be affected by the different population densities at rice growth stage. Although the BPH prefered a ovi-positional location for the lower portion at seeding, booting and heading stages, its preference-was somewhat reduced with the developmental stages of rice plants, whereas the WBPH showed a ovipositional preference for lower portion at seeding stages, but prefered the same tendency of ovipositional preference for the upper and the lower portion, The location and ovipositional preferences were likely to be affected by the competition between species with the mixed populations rather than single.

• Journal of Forest and Environmental Science
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• v.37 no.3
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• pp.206-216
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• 2021

Deutzia paniculata Nakai, a rare and endemic plant, has limited distribution throughout the North and South Gyeongsang provinces of South Korea. The D. paniculata community grows mostly on the stony slopes of forests, valley edges, and rock layers at 250-960 m in altitude, where deciduous trees are dominant and high humidity is maintained. Correlation analysis of vegetation and environmental factors found that the Walter's dogwood-mulberry community was correlated with soil acidity (pH). Whilst the queritron community had correlations with distance from the valley, rock rate and slope. The natural habitat of the Palgongsan Mountain in Daegu is known to have high genetic diversity, had eight D. paniculata individuals recorded from 2014 to 2018, and 12 individuals recorded in 2020 (new individuals due to a newly created space within the herbaceous layer caused by grass mowing works), it is therefore unlikely that the community would perish unless there was an artificial disturbance. To conserve the natural habitats of D. paniculata, oppression by Sasa borealis, damage, increase in crown density of the upper layer, overexploitation, and absence of seedlings should be carefully investigated. In addition, response measures should also be established and the impact on seed fullness and the reproductive characteristics of D. paniculata recorded. To restore declined genetic diversity, individuals from high genetic diversity regions, such as Palgongsan Mountain, should be artificially transplanted.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.406-414
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• 2022

Bolboschoenus planiculmis has been acknowledged as a key species in whooper swans (Cygnus cygnus) habitat by providing food for this migratory waterfowl. B. planiculmis wetlands are being degraded by water shortages and salinization caused by anthropogenic activities and climate changes. In 2004, the distribution of B. planiculmis in the tidal flats of the Nakdong Estuary was 2,475,568 m², and in 2021, the distribution area was 798,731 m², which decreased by 32.3%. In order to restore the degraded B. planiculmis wetlands, shoot transplantation and seed sowing were tentatively used in three places with different salinity and water levels. The average density per unit area in September at the optimal growth period after planting were A (fresh water level 50 cm) 58±15.65 m^-2, B (brackish water level 0~5 cm) 188±63.83 m^-2, C (brackish water level 0 cm or less) 188±45.13 m^-2. The tubers were observed as A 0 g dw m^-2, B 25.32±2.94 g dw m^-2, and C 13.39±0.91 g dw m^-2. Tubers were distributed in the soil, with only 3.0% at the 10~20 cm depth but 97.0% at the 0~10 cm depth. In contrast, the germination rate of B. planiculmis seeds was observed to be 0%. Results of this study provide technical support for the restoration of B. planiculmis wetland and the improvement in the quality of whooper swans habitat.

• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.188-195
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• 2010

The Abundance of zooplankton was studied in the pelagic and the littoral zone in four shallow reservoirs along with the Nakdong river basin of S. Korea. In the pelagic zone, there was a higher zooplankton density ($477.5{\pm}312.4$ ind. $L^{-1}$) than in the littoral zone during our study period (t=2.337, p<0.05). Overall, Rotifers were the most abundant group in the studied reservoirs. However, there are no significant correlations between the pelagic and the littoral zone in physical and chemical parameters. In the pelagic and the littoral zone, zooplankton density usually increased with increasing density of aquatic plants in the littoral zone. However, this study showed different trends. Although macrophyte abundance was higher in the littoral zone than in the pelagic zone, zooplankton abundance was higher in pelagic zone. Moreover, when macrophytes (Trapa japonica and Spirodela plyrhiza) covered the complete water surface of the reservoir, zooplankton abundance was higher. It appears that comparisons between the pelagic and the littoral zone give important cues on the selection of habitats by zooplankton. It is assumed that a higher density of aquatic plants does not always imply a higher density of zooplankton in the littoral zone. Furthermore, when the water surface was covered with aquatic plants, the zooplankton communities showed the highest density in the pelagic zone. These results imply that habitat selection of the zooplankton community (Rotifers) is influenced by aquatic plant density with an associated decrease in predation pressure during summer.

• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.358-365
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• 2019

We measured the body composition, including bone mineral density (BMD) and food resource availability using dual energy X-ray absorptiometry and the carbon and nitrogen stable isotope ratios of body condition of 4 anuran species(Hyla japonica, Glandirana rugosa, Pelophylax nigromaculatus, Lithobates catesbeianus) in South Korea. Additionally, the carbon and nitrogen stable isotope ratios were employed to determine the food resource availability of anurans. We figured out the relationship between the body composition, including BMDs and food resource availability. The body composition and BMDs did not differ between male and female while there was difference among the species. Food resource availability and BMDs were the highest in L. catesbeianus, the lowest in H. japonica. BMDs tended to increase with higher food resource availability. Body composition and BMDs, which represent the body condition of an individual, can be used as an ecological indicator to assess the stability of the habitat of anurans.

• Journal of Ecology and Environment
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• v.41 no.1
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• pp.1-8
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• 2017

Background: Though the biomass of floral vegetation in understory plant communities in a forested ecosystem only accounts for less than 1% of the total biomass of a forest, they contain most of the floral resources of a forest. The diversity of understory honey plants determines visitation rate of pollinators such as honey bee (Apis mellifera) as they provide rich food resources. Since the flower visitation and foraging activity of pollinators lead to the provision of pollination service, it also means the enhancement of plant-pollinator relationship. Therefore, an appropriate management scheme for understory vegetation is essential in order to conserve pollinator population that is decreasing due to habitat destruction and disease infection. This research examined the diversity of understory honey plant and studied how it is related to environmental variables such as (1) canopy density, (2) horizontal heterogeneity of canopy surface height, (3) slope gradient, and (4) distance from roads. Vegetation survey data of 39 plots of mixed forests in Chuncheon, Korea, were used, and possible management practices for understory vegetation were suggested. Results: This study found that 113 species among 141 species of honey plant of the forests were classified as understory vegetation. Also, the understory honey plant diversity is significantly positively correlated with distance from the nearest road and horizontal heterogeneity of canopy surface height and negatively correlated with canopy density. Conclusions: The diversity of understory honey plant vegetation is correlated to vegetation structure and human impact. In order to enhance the diversity of understory honey plant, management of density and height of canopy is necessary. This study suggests that improved diversity of canopy cover through thinning of overstory vegetation can increase the diversity of understory honey plant species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.533-542
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• 2011

Numerous seagrass habitat restoration projects have been attempted recently due to the remarkable decline in seagrass coverage. Seagrass transplants tend to adapt to a new environment after experiencing transplanting stress during the early stages of transplantation. Once acclimated, the transplants grow into healthy seagrass beds via vegetative propagation. The establishment and growth dynamics of transplanted seagrasses in bays and coasts are widely reported, but few studies have been conducted on estuaries in Korea. We transplanted Zostera marina in November 2007 and November 2008 in the Nakdong estuary using the staple method, and monitored the survival, adaptation, and growth dynamics of the transplants as well as environmental factors every month for 1 year. Both transplants adapted well to the new environment without initial losses and showed rapid productivity during early summer. However, density of transplants increased 320% in 1 year from the previous year's transplants but that decreased to 59% during the following year. This significant reduction in density in the second year may have been caused by exposure to low salinity (10 psu) for 3 weeks during the unusually long monsoon season. While the survival and growth dynamics of seagrass transplants planted in bays and coasts are mainly controlled by underwater photon flux density and water temperature, salinity was the critical factor for those planted in Nakdong estuary.

• Journal of Environmental Impact Assessment
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• v.27 no.2
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• pp.203-214
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• 2018

The purpose of this study is to estimate the concentrated distribution area of nutria (Myocastor coypus) and potential suitable habitat and to provide useful data for the effective management direction setting. Based on the nationwide distribution data of nutria, the cross-validation value was applied to analyze the distribution density. As a result, the concentrated distribution areas thatrequired preferential elimination is found in 14 administrative areas including Busan Metropolitan City, Daegu Metropolitan City, 11 cities and counties in Gyeongsangnam-do and 1 county in Gyeongsangbuk-do. In the potential suitable habitat estimation using a MaxEnt (Maximum Entropy) model, the possibility of emergency was found in the Nakdong River middle and lower stream area and the Seomjin riverlower stream area and Gahwacheon River area. As for the contribution by variables of a model, it showed DEM, precipitation of driest month, min temperature of coldest month and distance from river had contribution from the highest order. In terms of the relation with the probability of appearance, the probability of emergence was higher than the threshold value in areas with less than 34m of altitude, with $-5.7^{\circ}C{\sim}-0.6^{\circ}C$ of min temperature of the coldest month, with 15-30mm of precipitation of the driest month and with less than 1,373m away from the river. Variables that Altitude, existence of water and wintertemperature affected settlement and expansion of nutria, considering the research results and the physiological and ecological characteristics of nutria. Therefore, it is necessary to reflect them as important variables in the future habitable area detection and expansion estimation modeling. It must be essential to distinguish the concentrated distribution area and the management area of invasive alien species such as nutria and to establish and apply a suitable management strategy to the management site for the permanent control. The results in this study can be used as useful data for a strategic management such as rapid management on the preferential management area and preemptive and preventive management on the possible spreading area.

• Korean Journal of Environment and Ecology
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• v.21 no.4
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• pp.311-317
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• 2007

This study was conducted to determine the geographical distribution and habitat for Rana catesbeiana and Trachemys scripta elegans in order to obtain the current basic data on biota needed for establishing a database on non-indigenous species(NIS) in Jeju-do and to develop management plans applicable to Jeju, starting from March 2005 until May 2006. As a result of an inspection, it was found that the habitat for R. catesbeiana in Jeju includes Hankyeong-myeon, Daejeong-eup, and Ahndeok-myeon. These areas are all located on the western side of Jeju-do, and considered to have favorable conditions for R. catesbeiana to inhabit. Thus, it is unlikely that the population of R. catesbeiana will possibly decrease; what's worse, there exists even a risk that it could not only expand to other regions but also do damage to the population of native insecta, fishes, amphibians and reptiles, so this terrible species ought to be exterminated. More than 92 individuals of T. scripta elegans species were found to inhabit in 15 ponds around Jeju Island. T. scripta elegans. as the topmost predator, could destruct the pond ecosystem, and also cause a problem of water pollution due to its excrement. Counter-measures against T. scripta elegans could include publicity activities encouraging self-control of the release of captive T. scripta elegans, extermination plans using its ecological habits, and sign-posting publicizing its hazard to healthy ecosystem at the areas with high population density of T. scripta elegans or at its habitats with high foot traffic, together with the continuous management of NIS(none-indigenous species).

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.321-338
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• 2014

In the Natural Monument (No. 432) Jeju Sanghyo-dong Cymbidium kanran Habitat (39 ha), flora, vegetation diversity, stand structure, mirco-climate, canopy openness, light environment and soil temperature and moisture were quantified from Oct. 2013 to Feb. 2014. Compare to Seogwipo-si, daily mean temperature ($5.7^{\circ}C$) and moisture (75.8%) in study area were lower at $3.3^{\circ}C$ and 15%, respectively. Mean soil temperature and moisture were $16.5^{\circ}C$ and 37.3%, respectively, and mean litter layer depth (n = 81) was 4.3 cm. Mean canopy openness and light availability at forest floor were 15.5% and $8.5mol{\cdot}m^{-2}{\cdot}day^{-1}$, respectively. Total of 22 species including vascular and bryophyte plants and 6 vegetation group were observed. Castanopsis siebildii was dominant species in study area, and density and basal area were 1,777 stem/ha and $90.3m^2/ha$.