• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.441-448
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• 2008

The purpose of this study was to analyze chemical water quality, fish trophic guilds, tolerance indicators, and fish community conditions in the Gap Stream and to compare the stream conditions between the unimpacted site and impacted site. This study was conducted in the physically stable season (May 2008) to minimize physical impacts such as flow and hydrological disturbance, and applied the study in the Gap Stream with two sites of unimpacted upstream site (Unim-S), mainly surrounded by forested area and impacted site (Im-S), influenced by the wastewater disposal plants and industrial complex in the urban region. Chemical data analysis showed that the degree of organic matter pollution, based on BOD, and COD, was $2{\sim}3$ fold greater in the Im-S than the Unim-S, and that TP, as eutrophication indicators, was 4.7 fold greater in the Im-S. Also, $NH_3-N$ was in 8.2 fold greater in the Im-S ($6.25\;mg\;L^{-1}$) than the Unim-S ($0.76\;mg\;L^{-1}$), indicating a massive influence of wastewater from the disposal plant. Similar results were found in other chemical parameters. Thus, chemical impacts in the Im-S were evident, compared to the unimpacted site. Evaluations of tolerant indicator species indicated that sensitive species were dominant in the Unim-S (23.9%) and tolerant species were dominant (97.8%) in the Im-S. Condition factor (CF) was averaged 0.95 ($0.68{\sim}1.18$) in the Unim-S and 1.08 ($0.93{\sim}1.22$) in the Im-S. Fish community in the Unim-S and Im-S was categorized as Zacco-community and Hemibarbus-community, respectively, and the community diversity index (H') was significantly (p<0.05) higher in the Unim-S (0.810) than the Im-S (0.466). Overall, our results suggest that the comparison approach of various chemical and ecological indicators provide important information in identifying multiple stressors in the stream ecosystems.

• Korean Journal of Environment and Ecology
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• v.17 no.2
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• pp.123-132
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• 2003

This ecological study investigated the vegetation changes of abandoned salt field, 21 plots(1${\times}$lm, 1${\times}$2m) set up by the methods of Braun-Blanquet and Elenberg in a coastal island, Gasado, Jindogun, from July to September,2002. The vascular plants of abandoned salt field in the surveyed site identified 17 families and 48 species. Of these species, halophytes and mesophytes were 20(42%) and 28(58%) species. In addition, the disturbance to this habitat led to the change of halophytes in abandoned sald field, exotic plants was distributed 23 species, which included Dactylis glomerata, Conyza canadensis, Oenothera odorata, Cosmos bipinnatus, etc., in the group of, mesophytes were 20(71%) species, vegetation communities were classified into 3 community types, i.e. the halophyte grassland community(Limonium tetragonum community, Suaeda japonica community, Spergularia marina community), the wetland grassland community(Phragmites communis community, Carex scabrifolia community, Phaceturus latifolius var. angustifolius community), and the mesophyte grassland community(Erigeron bonariensis community, Daucus littoralis var. koreana community). Each communities was described the structual, distribution and changes of the vegetation in the abandoned salt field, the vegetation table and actual vegetation map were prepared.

• Journal of Ecology and Environment
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• v.32 no.2
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• pp.87-96
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• 2009

Pinus thunbergii plantations in Pohang-si, Gyeongsangbuk-do, Korea, are of low ecological quality, with arrested succession and a high proportion of ruderal species. To improve the quality of the habitat, we created canopy gaps ($\sim42\;m^2$) and monitored changes in abiotic (light availability, canopy openness) and biotic (survival and growth of seedlings and understory communities) variables in 2007 and 2008 in plots that had received one of five types of treatment: cutting of canopy trees and removal of the understory (CU), cutting of canopy trees only (C), girdling of canopy trees and removal of the understory (GU), girdling of canopy trees (G) or control. Each treatment was applied to three replicate plots. Abiotic variables did not significantly differ among treatments. Survival rates of target species were slightly lower in the CU, G and control conditions. Based on logistic regression analysis, the only significant growth factor affecting survival was height growth. Positive effects of seedling height and leaf area growth on survival were also detected, but did not reach statistical significance. In treatment G, gradual improvement of overstory conditions and mitigation of competition by limitation of disturbance to the understory community were likely to have promoted seedling growth. There were no significant effects of gap treatments on changes in species abundance (cover and richness) and composition of understory between the study years. This result implies that the small gaps created in our study may be below the threshold size to affect understory growth. However, the results of this study are based on a short-term investigation of only two years. Long-term research is strongly recommended to clarify the effects of gap treatment on plant communities in afforested areas.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.5
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• pp.101-109
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• 2009

There are increasing needs about creation and sustainable management of urban forest for environmental conservation and recreational service for citizen. However, it is difficult for local governments to create or manage urban forest in recreational or conservational way. The purpose of this study is to classify the urban forest types by considering its geographical feature, biological and sociological characteristics in order to suggest a guide to local governments about effective creation or management of urban forest. In this study, we extracted common characteristics of the selected five indicators. Factors about urban forest are divided into two groups. Factors were named according to the variables as 'Urban Forest Naturalness', and 'High Accessibility and Disturbed by Human.' In addition, we classified urban forests into four types in this study. The type I of urban forest is a large forest and has high naturalness such as Mt. Bukhan and Mt. Gwanak. The type II is fragmented to large forests by developmental projects. The type III is flat and has high accessibility such as forest behind Seonjeongneung. The type IV is located near residential area such as Mt. Ansan, Mt. Inwang and Mt. Bonghwa. It is possible to set up recreational area for citizens and ecological networks for species by the research of the urban forest type. The results of the study, classification of urban forest types and its application, contribute to provide a guide for local governments to create or manage urban forests effectively.

• Journal of Environmental Impact Assessment
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• v.15 no.5
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• pp.339-355
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• 2006

In this paper, we reviewed the assessment criteria and conservation value used to evaluate vegetation. The Degree of Green Naturality (DGN) and the Grade of Vegetation Conservation (GVC) are both sets of criteria that estimate the degree of human disturbance or natural value of vegetation. The criteria are extensively used in decision-making about the natural environment conservation and environment impact assessment. Sometimes, social issues can rise because the criteria are not clear. This study aims to evaluate the criteria based on the many aspects of the related literatures and suggest reasonable revised criteria. In addition, criteria for representing the relative value of valuable vegetation conservation are suggested. The DGN and GVC are essentially same; both have 11 degrees and 5 grades. While the DGN is subdivided into levels of anthropogenic disturbances, the GVC indicates the priority for conserving valuable vegetation. Therefore, the DGN is very useful for assessing land development projects, etc., while the GVC is needed to delineate the Ecological Assessment Map(EAM). In conclusion, it is desirable that both criteria should be used together appropriately.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.162-177
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• 2020

Background: Ecologists have achieved much progress in the study of mechanisms that maintain species coexistence and diversity. In this paper, we reviewed a wide range of past research related to these topics, focusing on five theoretical bodies: (1) coexistence by niche differentiation, (2) coexistence without niche differentiation, (3) coexistence along environmental stress gradients, (4) coexistence under non-equilibrium versus equilibrium conditions, and (5) modern perspectives. Results: From the review, we identified that there are few models that can be generally and confidently applicable to different ecological systems. This problem arises mainly because most theories have not been substantiated by enough empirical research based on field data to test various coexistence hypotheses at different spatial scales. We also found that little is still known about the mechanisms of species coexistence under harsh environmental conditions. This is because most previous models treat disturbance as a key factor shaping community structure, but they do not explicitly deal with stressful systems with non-lethal conditions. We evaluated the mainstream ideas of niche differentiation and stochasticity for the coexistence of plant species across salt marsh creeks in southwestern Denmark. The results showed that diversity indices, such as Shannon-Wiener diversity, richness, and evenness, decreased with increasing surface elevation and increased with increasing niche overlap and niche breadth. The two niche parameters linearly decreased with increasing elevation. These findings imply a substantial influence of an equalizing mechanism that reduces differences in relative fitness among species in the highly stressful environments of the marsh. We propose that species evenness increases under very harsh conditions if the associated stress is not lethal. Finally, we present a conceptual model of patterns related to the level of environmental stress and niche characteristics along a microhabitat gradient (i.e., surface elevation). Conclusions: The ecology of stressful systems with non-lethal conditions will be increasingly important as ongoing global-scale climate change extends the period of chronic stresses that are not necessarily fatal to inhabiting plants. We recommend that more ecologists continue this line of research.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.2
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• pp.62-73
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• 2001

The riparian environments of urban streams in Korea have been disturbed through the channelization for flood control and artificial land use as well as water pollution and flow decrease due to industrialization and urbanization. The flora and vegetation structure were investigated and an implication of stream restoration was discussed for the conservation of biodiversity in the riparian area of the Seunggi stream in Incheon. Naturalized plants and ruderal plants were widely distributed in the riparian area which was disturbed from cultivating, trampling, dumping etc. Submerged and floating hydrophytes were not found in the stream due to channelization and water pollution. Some halophytes were remained in downstream and reservoir after reclamation and embankment. The communities of Humulus japonicus, Panicum dichotomiflorum, Digitaria sanguinalis, Artemisia montana, Amaranthus retroflexus, and Aster pilosus were distributed in the disturbed area of bank slope and floodplain in the stream. As a natural potential vegetation, Phragmites australis in the wet meadow, Typha latifolia, Typha angustifolia, Oenanthe javanica, Persicaria thunbergii, and Penthorum chinense in the marsh, and Salix babylonica and Salix matsudana for. tortuosa in the woodland appeared in the floodplain. The topography in the stream played an important role on the distribution of riparian vegetation in the Seunggi stream. Appropriate methods for conservation and restoration of the riparian ecosystems must be planned on the basis of the actual vegetation in the disturbed urban stream.

• Journal of Ecology and Environment
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• v.31 no.4
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• pp.269-276
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• 2008

In order to understand the role of seed banks for restoration, seed banks in abandoned rice fields in the Gwangneung National Arboretum, central Korea were investigated using the seedling emergence method. The study sites represented three stages: an initial stage dominated by forbs such as Persicaria thunbergii and Juncus effuses var. decipiens, a middle stage dominated by Salix, and a late stage dominated by Quercus aliena and Prunus padus (in nearby riparian forest chosen as a reference stand). DCA ordination arranged the stands according to the number of years since abandonment. CCA ordination identified the dominant environmental variables correlated most closely with Axes 1 and 2 as $Mg^{2+}$ (intraset correlation was 0.827) and $K^+$ (intraset correlation was -0.677), respectively. Species richness and diversity decreased from the initial stage (H'=2.61) to the middle (H'=1.79) and late (H'=0.75) stages. A total of 49 species $(/m^2)$ and 18,620 seedlings $(/m^2)$ emerged out of the seed bank samples. The DCA ordination and similarity analysis detected a large discrepancy between the composition of the actual vegetation and the seed bank. We conclude that the contribution of seed bank to restoration is low. However, seed bank may help the recovery of forbs after disturbance. Some of our results are consistent with the tolerance model of succession whereas others follow the trajectory of the facilitation model. More research on succession will be required to understand the underlying mechanisms.

• Korean Journal of Environment and Ecology
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• v.12 no.4
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• pp.331-344
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• 1999

To study plant community structure and successional sere of the Kojedo District, Hallyo-Haesang National Park, fifty six plots were set up and surveyed(each plot $l00\m^2$). Fifty-six plots were classified into four community, Quercus variabilis-Zelkova serrata community(I), Q. variabilis-Cinnamomum japonicum-Neolitsea sericea community(II), Pinus thunbergii-C. japonicum-N. sericea community(III), P. thunbergii-P. densiflora community(IV) by TWINSPAN technique. Most area of forests in Kojedo district are artificial or coppice forest after artificial disturbance. The age of four community were about 35~40 years and the number of species 32~44 species per $600\m^2$. Ecological succession had been proceeded from deciduous broad-leaved species(Q. variabilis-Z. serrata etc.), P. thunbergii, P. densiflora to evergreen broad leaved forest(C. japonicum, N. sericea etc.).

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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• pp.157-165
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• 2015

The purpose of this study is on identifying charactreistics and management direction of complementary pond of Dalmaji village in Gangjin. Accordingly, this village was indicated as Experience and Resort village by Korean government. This study describes the construction background and characteristics and identifies species diversity and characteristics through field survey. For this, literature and field survey was performed. In field survey, vegetational survey was performed in Aug. of 2015. D(Dominant degree) and S(Sociability degree) was measured by Brown-Blanquet's method. The answer was searched from Myungsanron(明山論), a textbook of Fengsui(風水) in Joseon dynasty. Of these causes, it was considered that the representative one is a protection of fire and infectious disease because the Wolgak mountain is a fire mountain(火山) as a stone mountain in Fengsui. The results demonstrate decline of aquatic ecosystem because of neglect management. The total number of species was 24. Of the species, Zelkova serrata is a natural vegetation of this complementary forest. This is nominated as Lagerstroemia indica and Camellia japonica community. Species composition demonstrate the characteristics of Korean southern region as mixed forest of evergreen trees and deciduous ones which are indigenous plants. It was considered Juniperus chinensis KaizukaVariega in central round island was planted in Japanese colonial period and it have to be removed. It was considered that name of moon pond and moon island etc. projects the mind of village ancestors which are going to reach an ideal condition of moon. And management of quantity and depth of pond water was critical for restoration of disappearing lotus from related literature. Periodic management was needed for ecological structure and function improvement because of ecological disturbance by the invasive plants like Humulus japonicus.