• The Plant Pathology Journal
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• v.37 no.6
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• pp.662-672
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• 2021

Plant growth-promoting bacteria improve plant growth under abiotic stress conditions. However, their effects on microbial succession in the rhizosphere are poorly understood. In this study, the inoculants of Bacillus mesonae strain H20-5 were administered to tomato plants grown in soils with different salinity levels (EC of 2, 4, and 6 dS/m). The bacterial communities in the bulk and rhizosphere soils were examined 14 days after H20-5 treatment using Illumina MiSeq sequencing of the bacterial 16S rRNA gene. Although the abundance of H20-5 rapidly decreased in the bulk and rhizosphere soils, a shift in the bacterial community was observed following H20-5 treatment. The variation in bacterial communities due to H20-5 treatment was higher in the rhizosphere than in the bulk soils. Additionally, the bacterial species richness and diversity were greater in the H20-5 treated rhizosphere than in the control. The composition and structure of the bacterial communities varied with soil salinity levels, and those in the H20-5 treated rhizosphere soil were clustered. The members of Actinobacteria genera, including Kineosporia, Virgisporangium, Actinoplanes, Gaiella, Blastococcus, and Solirubrobacter, were enriched in the H20-5 treated rhizosphere soils. The microbial co-occurrence network of the bacterial community in the H20-5 treated rhizosphere soils had more modules and keystone taxa compared to the control. These findings revealed that the strain H20-5 induced systemic tolerance in tomato plants and influenced the diversity, composition, structure, and network of bacterial communities. The bacterial community in the H20-5 treated rhizosphere soils also appeared to be relatively stable to soil salinity changes.

• Korean Journal of Environmental Biology
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• v.35 no.2
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• pp.143-151
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• 2017

This study illustrates changes in the epilithic diatom assemblages in response to urban climatic conditions. We further assess the impact of abnormal urban climate to the urban stream environment. Epilithic diatoms, water chemical and physical variables were sampled every quarter, and assessed at 3 Oncheon stream sites, for a period of two years(from 2013~2014). The variation of physiochemical properties such as BOD, COD, T-N and T-P, show that the water quality was strongly influenced with long periods of drought and flood disturbance. Epilithic diatom assemblages were separated along the stream sites; however, the physical disturbance from urban drought and stormwater changed the composition of diatom assemblages instead of decreasing the taxonomic richness. Thus, our results suggest that epilithic diatom assemblages are altered in response to urban climatic changes, resulting in variations of stream conditions. Hence, strategies of climate change adaptation are required when considering urban stream environments.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.213-223
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• 2008

The increasing area of abandoned rice fields could provide new opportunities for wetland restoration in Asia. However, it is unknown how quickly or completely abandoned rice fields will recover from agricultural disturbances. We assessed water quality and plant community succession in abandoned rice fields with different hydrology in a mountain valley to understand the effects of hydrological regime on recovery. Water level, soil redox potential, water quality, plant composition, and primary production were measured. The sites, coded as D6, N13, and N16, had been recovering for 6, 13, and 16 years by 2006. N13 and N16 have been recovering naturally whereas D6 has been drained with a nearby dike and was tilled in 2001. The typical hydroperiods of D6, N13, and N16 were no surface water, permanently flooded, and seasonally flooded, respectively. The major change in vegetation structure of both D6 and N13 was the replacement of herbaceous species by woody species. Drawdown accelerated this change because Salix koreensis grew better in damp conditions than in flooded conditions. Phragmites japonica reduced plot-level plant species richness. The removal efficiency of $NH_4-N$, $NO_3-N$, and $PO_4-P$ from water varied seasonally, ranging between -78.8 to 44.3%, 0 to 97.5%, and -26.0 to 44.4%, respectively. In summary, abandoned rice fields quickly became suitable habitat for native wetland plant species and improved regional water quality. Variation among our sites indicates that it is likely possible to manage abandoned rice fields, mostly through controlling hydrology, to achieve site-specific restoration goals.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.265-271
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• 2018

Background: Temperature-driven variation in pollinator assemblage and activity are important information, especially at high altitudes, where rising temperature trends exceed global levels. Temporal patterns of pollinators in a flowering season can be used as a proxy to predict the changes of high-altitude plants' mutualistic relationships. We observed a spring temperature change in one population of a high-altitude endemic species, Megaleranthis saniculifolia on Mt. Sobaeksan, and related it to pollinator assemblage and activity changes. Methods: This study was conducted at two sites, each facing different slopes (NE and NW), for two times in the spring of 2013 (early-flowering, April 27-28, vs. mid-flowering, May 7-8, 2013). We confirmed that the two sites were comparable in snowmelt regime, composition of flowering plants, and flower density, which could affect pollinator assemblage and activity. Pollinator assemblage and activity were investigated at three quadrats ($1m^2$ with 5-m distance) for each site, covering a total of 840 min observation for each site. We analyzed correlations between the temperature and visitation frequency. Results: Twelve pollinator species belonging to four orders were observed for M. saniculifolia at both sites during early- and mid-flowering times. Diptera (five species) and hymenopteran species (four species) were the most abundant pollinators. Pollinator richness increased at both sites toward the mid-flowering time [early vs. mid = 7 (NE) and 3 (NW) vs. 9 (NE) and 5 (NW)]. Compared to the early-flowering time, visitation frequency showed a fourfold increase in the mid-flowering time. With the progression of spring, major pollinators changed from flies to bees. Upon using data pooled over both sites and flowering times, hourly visitation frequency was strongly positively correlated with hourly mean air temperature. Conclusions: The spring temperature change over a relatively brief flowering period of M. saniculifolia at high altitudes can alter pollinator assemblages through pollinator dominance and visitation frequency changes. Thus, this study emphasizes information on intra- and inter-annual variations in the mutualistic relationship between pollinators and M. saniculifolia to further assess the warming impacts on M. saniculifolia's reproductive fitness.

• Journal of Ecology and Environment
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• v.34 no.4
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• pp.381-391
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• 2011

Many lichens have been used as bioindicators for air pollutants such as $SO_2$. The first ecological study on lichens in Korea was conducted in 1975 by Kim and Lee, disclosing that areas adjacent to the center of Seoul were lichen deserts. Air quality in Seoul has improved significantly since the 1980s. However, the distribution of lichen species has not been reevaluated since then. We examined the spatial and temporal pattern of lichen distribution by selecting six (inner city green [ICG] and four (outer city green [OCG]) sites, based on the distance from the city center of Seoul and the land use pattern. The change in lichen distribution was related to yearly mean concentrations of $SO_2$, $NO_2$, and $O_3$ for the years 1980-2009. Four and 13 lichen species were found in ICGs and OCGs, respectively. Although mean sample numbers per species were much higher in the former, species richness tended to increase with distance from the city center. Since 1980, $SO_2$ has declined drastically to < 0.01 ppm in both ICGs and OCGs, indicating that $SO_2$ is no longer a limiting factor for lichen establishment and growth. In contrast, $NO_2$ has increased steadily for 20 years (1989-2009) and a considerable proportion of lichen species in both ICGs and OCGs are known as nitrophilic or pollution-tolerant species. Appearance of nitrophiles in both ICGs and OCGs and the dominance of a few lichen species in ICGs may reflect the effects of the increase in $NO_2$. In contrast to $SO_2$ and $NO_2$, $O_3$ was higher in OCGs, but it was difficult to identify a causal relationship between $O_3$ and lichen distribution.

• Journal of Korean Society on Water Environment
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• v.39 no.2
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• pp.181-193
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• 2023

Distribution changes in microalgae communities were studied in the Nakdonggang River at two sampling stations (St.1 Gyeongcheongyo Bridge (GB) and St.2 Daedong Wharf (DW)) at monthly intervals from January 2021 to November 2021. A total of 83 taxa included 82 species, 1 forma, belonging to 49 genera, 32 families, 21 orders, and 8 classes. The most important groups were Bacillariophyta and Chlorophyta. The number of species ranged from 5 to 24 in GB, and from 9 to 21 taxa in DW. The contribution of Bacillariophyta to the total species richness was the highest during all survey periods, and Chlorophyta yielded the next highest value in the study area. The dominant taxa were Aulacoseira ambigua, A. ambigua f. japonica, and Ulnaria acus in this study. Cluster analysis and non-metric multidimensional scaling (nMDS) analysis based on Bray- Curtis similarity identified 4 major groups, which corresponded to microalgae assemblages and their characteristic species. Correlation was analyzed through the CCA analysis. It was found that there was a correlation between the microalgae and environmental factors. It was revealed that the divided groups were distinguished because of the differences by the survey period. Therefore, seasonal change was judged as a major factor affecting the distribution of microalgae communities.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.1
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• pp.79-87
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• 2024

We seasonally examined marine macroalgal community structures in the subtidal zones at Gapado Island, Jeju, Korea, from February 2013 to November 2019. A total of 164 macroalgal species were identified, including 15 green, 40 brown, and 109 red algae. Species richness ranged from 54-106 species, with the maximum observed in 2013 and the minimum observed in 2015. Cladophora wrightiana var. minor, Ecklonia cava, Amphiroa anceps, Corallina aberrans, Corallina crassisima, Synarthrophyton chejuense, Sonderophycus capensis and Plocamium telfairiae occurred in all seasons. The average annual seaweed biomass was 1,258.22 g wet wt./m², ranging from 917.51 g/m² in 2017 to 1,551.95 g/m² in 2014. E. cava was the most dominant species, accounting for 46.57% of the total seaweed biomass. The subdominant species were P. telfairiae and A. anceps, comprising 8.64% (108.75 g/m²) and 6.65% (83.61 g/m²) of the total biomass, respectively. The vertical distribution of subtidal seaweeds were represented by E. cava and P. telfairiae at 5-20 m, A. anceps at 10-20 m, C. aberrans and C. crassisima at 5 m and C. wrightiana var. minor at 10 m. Cluster analysis revealed three distinct groups: group A (2014-2018), group B (2019) and group C (2013), indicating significant differences in the annual seaweed community.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.6
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• pp.740-746
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• 2011

Subtidal benthic macroalgal flora and community structure on barren grounds were examined seasonally along vertical shore gradients on the rocky shore of Hajung, Pohang, on the southeast coast of Korea, from February 2005 to November 2006. Twenty-six seaweed species were identified, including 5 green, 7 brown, and 14 red algae. The number of seaweed species ranged between 7 and 17 among seasons and between 13 and 20 species were found in vertical gradients along the shore. Over the study period, average seaweed biomass (g wet wt/$m^2$) was 299.88 g and it ranged seasonally from 120.99 to 620.00 g. Seaweed biomass declined with increasing seawater depth and ranged between 323.06 and 593.68 g. The dominant seaweed species, in terms of biomass, were Desmarestia ligulata and Sargassum honeri, which grew at depths between 5 and 10 m. The red alga Delisea pulchra was also abundant at a depth of 15 m. No seasonal patterns were found in community indices. Along vertical shore gradients, community indices showed different patterns; the dominance index increased and the richness, evenness, and diversity indices decreased with seawater depth.

• Animal Bioscience
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• v.36 no.3
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• pp.417-428
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• 2023

Objective: Few studies have genetically monitored chickens over time, and no research has been conducted on ducks. To ensure the sustainable management of key duck breeds, we used microsatellite markers to monitor Brown Tsaiya ducks over time genetically. Methods: The second, fourth, sixth to eighth generations of the Brown Tsaiya duck selected for feeding efficiency and control lines were included in this study to investigate the genetic variations, effective population size, population structure and the differentiation between populations over time with 11 microsatellite markers derived from Brown Tsaiya duck. Results: The results showed there were a slight decrease in the genetic variations and an increase in within-population inbreeding coefficient (F_IS) in both lines, but no consistent increase in F_IS was observed in each line. The effective population size in the second and eighth generations was 27.2 for the selected line and 23.9 for the control line. The change in allele richness showed a downward trend over time, and the selected line was slightly lower than the control line in each generation. The number of private alleles (N_p) in the selected line were higher than in the control line. Moderate differentiation was observed between the second and eighth generations in the selected line (F_ST = 0.0510) and the control line (F_ST = 0.0606). Overall, differentiation tended to increase with each generation, but genetic variation and structure did not change considerably after six generations in the two lines. Conclusion: This study provides a reference for poultry conservation and helps to implement cross-generation genetic monitoring and breeding plans in other duck breeds or lines to promote sustainable management.

• Korean Journal of Environment and Ecology
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• v.32 no.4
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• pp.381-391
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• 2018

The purpose of this study is to investigate the influence of artificial disturbances occurring during water conveyance frequency on benthic macro-invertebrate by comparing and analyzing data before and after the construction of Boryeong dam in Boryeong-si, Chungcheongnam-do. We conducted the survey eight times in four points from April 2016 to September 2017. A total of 13,447 individuals from 125 species, 70 families, 19 orders, 7 classes, and 4 phyla were collected. The result of the community analysis showed that the dominant index was 0.55 (${\pm}0.07$) to 0.47 (${\pm}0.08$), diversity index was 2.06 (${\pm}0.26$) to 2.23 (${\pm}0.28$), evenness index was 0.69 (${\pm}0.05$) to 0.70 (${\pm}0.04$), and richness index was 3.43 (${\pm}0.72$) to 4.03 (${\pm}0.91$). After conveyance, the dominance decreased while the diversity, evenness, and richness increased. The result of the functional group analysis showed the portion of scrapers, filtering-collectors increased while that of shredders, gathering-collectors decreased in the functional feeding group and that the proportion of climbers and clingers increased while that of burrowers and sprawlers decreased in the habitat orientation group. The result of analysis of community stability showed that St. 1 and St. 2 decreased resistance and resilience after conveyance and new species appeared in the III characteristics group while St. 3 and St. 4 did not show much difference. The result of multidimensional scaling analysis showed that the variation of similarity was the highest at St. 1 after conveyance, and the variation of similarity at St. 4 was the lowest.