• Korean Journal of Microbiology
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• v.50 no.2
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• pp.137-151
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• 2014

Various studies have been conducted to investigate effects of dams on river ecosystems, but less information is available regarding damming impacts on downstream denitrification. We measured denitrification enzyme activity (potential denitrification rate) and denitrifier abundances (using nirS, nirK, and nosZ as markers) in dammed headstreams of the Nakdong River in South Korea. Sediments in Phragmites-dominated riparian areas and in-stream areas across streams (dammed vs. reference) with different streambed materials (gravel and sand) were sampled occasionally. We hypothesized that (i) the higher available N and C contents in sediments downstream of dams foster larger denitrifier communities than in the reference system and (ii) differences in potential denitrification rates across the systems correspond with denitrifier abundances. Despite 30 years of different hydrological management with dams and greater inorganic N and DOC contents in sediments downstream of dams, compared to the references, abundances of denitrifier communities and potential denitrification rates within the whole sediment were not significantly different across the systems. However, nirS and nosZ denitrifier abundances and potential denitrification rates were considerably increased in specific sediments downstream of dams (gravelly riparian and sandy in-stream) with regard to flooding events and seasonal temperature variation. nirK was not amplified in all sediments. Canonical correspondence analyses (CCA) revealed that the relationship between abundances of denitrifier communities and nutrient availabilities and potential denitrification rates was a weak one.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.405-413
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• 2015

We classified the streamside plant community by phyto-sociological method and analyzed the relationship between environment factors and vegetation structure by using the classification and ordination method. We found that twenty one plant communities were classified according to dominant species at the natural streamside valley forest with surveying the 65 quadrats (10 m × 10 m). From the survey results, the hardwood plant communities were classified as streamside valley forest and the softwood plant communities as riparian forest according to the degree of flooding. The valley forest had a distribution of 17 plant communities which was 65% (42 quadrats) of 65 quadrats: Maackia amurensis community, Betula davurica community, Quercus variabilis community, Pinus densiflora community, Q. serrata community, Prunus sargentii community, and Meliosma oldhamii community etc. The riparian forest had a distribution of four plant communities which was 35% (23 quadrats) of 65 quadrats: Salix koreensis community, S. rorida community, S. purpurea var. japonica community, and S. glandulosa community, etc. From the two-way indicator species analysis (TWINSPAN) analysis, we found indicator species Oplismenus undulatifolius and Lindera obtusiloba for the streamside valley forest and Humulus japonicus, Phragmites japonica, and S. koreensis for the riparian forest. From the results of the canonical correspondence analysis (CCA), coordinates, altitude, and stream structure showed low correlation to the distribution of the plant community. Therefore, it seemed that valley forest and riparian forest were distinguished by the stream gradient and waterway width which determined by the stream water level.

• Journal of Environmental Science International
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• v.18 no.5
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• pp.579-588
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• 2009

The purpose of this study was to explain relationship between community structure and their environment variables in Mt. Hwaak. Samples were collected by 101 plots using ZM phytosociological method and followed by cluster, importance value and canonical correspondence analysis. The forest vegetation classified into 8 community types such as Pinus densiflora community, Berberis amurensis community, Betula ermani community, Betula schmidtii community, Larix leptolepis community, Pinus koraiensis community, Cornus controversa community and Salix koreensis community. Altitude was considered as the highest factor correlated to the community types. Berberis amurensis community and Betula ermani community were located in upper slope area of high elevation, Comus controversa community and Salix koreensis community in valley area, and Pinus densiflora community in ridge area, respectively.

• Journal of Forest and Environmental Science
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• v.32 no.3
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• pp.237-252
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• 2016

Improved knowledge of the environmental factors affecting the natural regeneration of tree species in limestone forest is urgently required for species conservation. We examined the environmental factors and tree species characteristics that are important for colonization in diverse forest stands growing on a limestone hill in northern Thailand. Our analysis estimated the relative influence of forest structure and environmental factors on the regeneration traits of tree species. We established sixty-four $100-m^2$ plots in four forest stands on the limestone hill. We determined the species composition of canopy trees, regenerating seedlings, and saplings in relation to the physical environment. The relationships between environmental variables and tree species abundance were assessed by canonical correspondence analysis (CCA), and we used generalized linear mixed models to examine data on seedling/sapling abundances. The CCA ordination indicated that the abundance of tree species within the mixed deciduous forest was closely related to soil depth. The abundances of tree species growing within the sink-hole and hill-slope stands were positively related to the extent of rocky outcropping; light and soil moisture positively influenced the abundance of tree species in the hill-cliff stand. Physical factors had a greater effect on tree regeneration than did factors related to forest structure. Tree species, such as Ficus macleilandii, Dracaena cochinchinensis, and Phyllanthus mirabilis within the hill-cliff or sink-hole stand, colonized well on large rocky outcroppings that were well illuminated and had soft soils. These species regenerated well under conditions prevailing on the limestone hill. The colonization of several species in other stands was negatively influenced by environmental conditions at these sites. We found that natural regeneration of tree species on the limestone hill was difficult because of the prevailing combination of physical and biological factors. The influence of these factors was species dependent, and the magnitude of effects varied across forest stands.

• Journal of Korean Society on Water Environment
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• v.34 no.1
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• pp.10-25
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• 2018

This study was conducted to estimate the habitat suitability of 17 benthic macroinvertebrate taxa in the Hwayang stream. Habitat Suitability Index (HSI) of benthic macroinvertebrates from the Hwayang stream was developed based on three physical habitat factors which include current velocity, water depth, and the substrate. The Weibull model was used as a probability density function to analyze the distribution of individual abundance by physical factors. The number of species and the total individual abundance increased along with the increase in current velocity. By means of Canonical Correspondence Analysis (CCA), the relative importance of each factor was determined in the following order: current velocity, water depth, and the mean diameter. The results depicted that, the most influential factor in the growth of benthic macroinvertebrates in the Hwavang system was current velocity. After comparing the analyzed results from the Hwayang stream with the resukts from the Gapyeong stream, the integrated HSI was drawn. The results indicated that current velocity and substrate had similar distributions of HSI in the two streams. This was due to the addition of unmeasured data from previous surveys, or the fact that benthic macroinvertebrates adapted to deeper waters in the Hwayang Stream. Most taxa showed a clear preference for a fast current velocity, deep water depth and coarse substrate except Baetiella, Epeorus, (mayflies), and Hydropsyche (caddisfly).

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.17-29
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• 2016

We conducted the study on the relationship between the distribution of coastal sand dune plants and edaphic factors from the shoreline to inland in sand dune ecosystem. The application of TWINSPAN classification based on 10 species, led to the recognition of three vegetative groups (A-C), which associated with their habitats (foredune, hummuck in semistable zone and stable zone). The associations were separated along soil gradient far from the seashore. The relationships between species composition and environmental gradients were explained by canonical correspondence analysis (CCA). Distance from the shoreline was an important indicator to determine soil properties (pH, total ion contents, sand particle sizes, organic matters and nitrogen contents) from the seaward area to inland area and distribution pattern of coastal sand dune plants. Group A is foredune zone, characterized by Calystegia soldanella; group included typical foredune species such as Elymus mollis, Carex kobomugi, Ixeris repens, C. soldanella and Glehnia littoralis. Group B on semi-stabilized zone was characterized by Vitex rotundifolia, a perennial woody shrub. This group was associated the proportion of fine sand size (100 to 250 μm). The results on the proportion of soil particle size showed a transition in sand composition, particularly with respect to the proportion of fine sand size that occurred from the foredune ridge at 32.5 m to the Vitex rotundifolia community at 57.5 m from the shoreline. Group C on stabilized zone was characterized by Zoysia macrostachya, Lathyrus japonicus and Cynodon dactylon and were associated soil organic matter and nitrogen contents. The spatial distribution of plants in the Goraebul coastal sand dune system may result from the interactions between the plant species and environmental heterogeneity.

• Ocean and Polar Research
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• v.34 no.1
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• pp.1-18
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• 2012

We investigated seasonal changes in the mesozooplankton community structure in November 2006 and February, May, and August 2007 at 12 stations in the semi-enclosed Muan Bay, Korea. Forty taxa were sampled, with an average abundance ranging from 1,459 to 20,078 indiv. $m^{-3}$; the highest abundance was detected in August 2007, and the lowest in February 2007. Acartia omorii, A. hudsonica, A. ohtsukai, Bestiolina coreana, Calanopia sp., Paracalanus parvus s. l., Cirripedia larvae, Decapoda larvae, and Gastropoda larvae were the most abundant taxa detected. The species diversity of the mesozooplankton was high around the inner regions in August 2007 but it was relatively low in November 2006. Non-metric multidimensional scaling (nMDS) revealed significant differences in the structure of mesozooplankton community among the seasons. Canonical correspondence analysis (CCA), performed to examine the relationships among dominant taxa, stations, and environmental variables, showed that most species of copepods were positively correlated with temperature, salinity, chlorophyll a, and COD concentration. Our results suggested that the mesozooplankton community structure observed in this study might be affected partly by the seasonal changes in environmental variables, such as the status of the sluice gates (i.e., open or closed) and the in situ production of resting eggs by major copepods.

• Ocean and Polar Research
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• v.28 no.3
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• pp.305-315
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• 2006

In order to examine the transition of zooplankton community by the Saemangeum sea dyke, the temporal and spatial distribution of zooplankton community with relation to environmental variables was investigated using data collected in 2004 and 2005. Sixty-one zooplankton taxa were identified. Average abundance (except Noctiluca scintiliam) ranged from 236 to 1810 indiv. $m^{-3}$, and was the highest in May 2005 and the lowest in february 2005. Dominant species were Acartia hongi and Paracalanus indicus, and cirripedia nauplii and zoea were dominant groups. After the closure of the 4th sea dyke, brackish species such as Tortanus derjugini and Pseudodiaptomus inopinus are widely distributed while the abundance of N. scintillans decreased in the northern area inside the dyke. In canonical correspondence analysis (CCA) for examining the relationships among zooplankton, stations and environmental variables, the northern area inside the dyke was distinguished from the other areas and was represented by Acartia spp, and brackish copepods.; Also, this area was characterized by high chlorophyll a concentration and COD, and low diversity.

• Journal of Korean Society of Forest Science
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• v.113 no.1
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• pp.51-65
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• 2024

Phyto-sociological methods were used in this study to assess the vegetation structure of a forest stand at Mt. Goehwa in Sejong-Si with the aim of providing vegetation information for urban forest utilization and management plans. The actual forest vegetation was classified into two types of community groups (Quercus serrata-Lindera obtusiloba and Coreopsis lanceolata community groups) at the highest hierarchical level. The Q. serrata-L. obtusiloba community group was classified into six units, which included artificial forest and natural forest vegetation. Artificial forests were classified into three communities (Pinus rigida, Castanea crenata, and Robinia pseudoacacia), whereas natural forests were classified into three communities (Quercus variabilis, Quercus acutissimaa, and Pinus densiflora). The Coreopsis lanceolata community group, which exhibited vegetative characteristics of urban forest edge areas, was categorized into four units. The urban forest edges were classified into four communities (Indigofera bungeana, Lespedeza bicolor, Amorpha fruticosa, and Lespedeza cuneata). Accordingly, the vegetation structure of Mt. Goehwa was categorized into 10 vegetation unit systems. An importance value analysis showed the highest importance value for C. crenata at 6.7%, followed by P. rigida at 6.4%, and R. pseudoacacia at 6.3%, indicating that the ecological impact of plantation species can be significant on Mt. Goehwa. A community coefficient of similarity analysis revealed that the artificial and natural forests had similar species compositions; however, both forests differed from the urban forest edge. This variation was further confirmed by Detrended correspondence analysis(DCA), with similar results. Canonical correspondence analysis(CCA) showed that the artificial forest and natural forest community types were positively correlated with altitude, bare rock, and the present species. By contrast, the urban forest edge community types were negatively correlated with these factors.

• The Korean Journal of Ecology
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• v.23 no.3
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• pp.281-291
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• 2000

The objectives of this study were to classify quantitatively vegetational types of P. densiflora for. erecta forest. The results were summarized as follows. 1) According to the canonical correspondence analysis(CCA), variables such as topography, altitude, available P/sub 2/O/sub 5/, and Mg/sup 2＋/were highly correlated on three axes. Based on the correlations between vegetation units and environmental factors, Rhododendron micranthum community tended to be more distributed in the such situations of high altitude, upper topography, high C/N ratio, low level of Mg/sup 2＋/and Ca/sup 2＋/. Vaccinium koreanum community tended to be more distributed in the such conditions of high altitude, upper topography, high level of Ca/sup 2＋/and Ma/sup 2＋/. 2) According to the results of importance value analysis, Tree layer and Subtree layer in study areas showed high Ⅳ along with P. densiflora for. erecta, Quercus mongonlica, Q. variabilis, Q. serrata, Fraxinus rhychophylla and shrub layer indicated that Ⅳ of P. densiflora for, erecta in Sokwang-ri area was higher than those of the other areas. Therefore, it was considered that P. densiflora for. erecta forest of Sokwang-ri area could be naturally regenerated. 3) According to results of species diversity, the species diversity of Uljin region showed the least low value as 0.6622, other regions appeared about 0.7. In the diversity by vegetation types, Acer pseudosieboldianum community showed high value. 4) According to the analysis of community similarity, Sokwang-Ri region was lowly correlated with Uljin region, while the index among the other areas appeared above 0.6. 5) According to the analysis of interspecific association, it was divided into 2 groups. The species of first group were mainly involved in character species, and the species of second group were involved in differential species groups.