• Journal of Environmental Impact Assessment
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• v.23 no.4
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• pp.315-322
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• 2014

After the modern industrial revolution, rivers in cities became covered and disappeared due to the pressure to develop them. Likewise, their function which is to serve as the basis of natural ecology system in the cities began to be damaged. This research demonstrated that there are a total of 268 categories when it comes to the list of plants, including 64 families, 179 genera, 230 species, 36 varieties, and 1 subspecies. When the relative abundance of the plants that were found at the target research site was studied, the secondary survey demonstrated Bromus japonicus 22.97, Artemisia princeps var. orientalis 16.76 and Erigeron annuus 15.69 while third survey demonstrated Digitaria ciliaris 26.78, Ambrosia trifida 16.29 and Aster pilosus 14.31. There were 54 species of naturalized plants that appeared. Analysis demonstrated annual plant 23 classification category (43%), perennial 11 classification category (20%), multi-perennation 17 classification category (31%), woody plant 3 classification category (6%) and others. When the naturalized plants that were found at the target research site were analyzed by the place of origin, North America and EU took up 76%, which accounts for 3/4 of the all the naturalized plants. At the target research site, naturalization degree of 5 pertained to 22 classification category (41%), which was the highest, followed by 19 classification category (35%) with naturalization degree of 3, 8 classification category (15%) with naturalization degree of 2 and 5 classification category (9%) with naturalization degree of 4 in the order mentioned. Flora of Jungnangcheon did not manifest any change compared to 10 years ago. Thus, it is necessary to increase of biodiversity efforts to improve SeoulCity's natural environment and cityscape.

• Journal of Environmental Impact Assessment
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• v.24 no.4
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• pp.352-366
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• 2015

The purpose of this study is to offer the basic data to the habitat conservation and management by surveying and analysing the ecological characteristics such as the flora, vegetation structure and soil of Rhodotypos scandens habitat. The flora were summarized as 131 taxa including 57 families, 99 genera, 107 species, 1 subspecies, 17 varieties and 6 forms. The life forms grouped as in the follows; the megaphanerophytes(MM) were 21 taxa, 24 taxa of the microphanerophytes(M), 30 taxa of nanophanerophytes(N), 6 taxa of chamaiphytes(Ch), 20 taxa of hemicryptophytes(H), 17 taxa of geophytes(G), 12 taxa of therophytes(Th) and 1 taxa of hydrophytes(HH). The present conditions of communities were 8 types including Zelkova serrata, Quercus aliena, Ulmus parvifolia, Rhamnella frangulioides, Castanea crenata, Albizia julibrissin, Celtis sinensis and Robinia pseudoacacia. In case of the dominant species by layers, the tree layer species were Zelkova serrata, Quercus aliena, Ulmus parvifolia, Castanea crenata, Albizia julibrissin, Celtis sinensis and Robinia pseudoacacia, and the subtree layer species were Rhamnella frangulioides, Q. aliena, Z. serrata, A. julibrissin, U. parvifolia and Broussonetia kazinoki. The shrub layer species was Rhodotypos scandens. In the results of analyzing the diversity index, $H^{\prime}{_{max}}$ from 1.691 to 2.610, from 2.197 to 3.466 in H'max, from 0.646 to 0.903 in J' and from 0.097 to 0.354 in D. In the results of analysing the soil, there showed that acidity was 5.6, 0.5dS/m of electrical conductivity(EC), 59.1mg/kg of available $P_2O_5$, 49.7% of organic matter content, $0.4cmol^+/kg$ of exchangeable $K^+$, $13.5cmol^+/kg$ of exchangeable $Ca^{2+}$, $3.3cmol^+/kg$ of exchangeable $Mg^{2+}$.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.465-478
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• 1995

The objective of this study was to investigate the impacts of large-scale timber harvesting on the environment of a mature hardwood forest. To achieve the objective, the effects of harvesting on forest environmental factors were analyzed quantitatively using the field data measured in the study sites of Seoul National University Research Forests [(Mt.) Paekunsan] for two years(1993-1994) following timber harvesting. The field data include information on vegetation, soil mesofauna, physicochemical characteristics of soil, surface water runoff, water quality in the stream, and hillslope erosion. For comparison, field data for each environmental factor were collected in forest areas disturbed by logging and undisturbed, separately. The results of this study were as follows : The diversity of vegetational species increased in the harvested sites. However, the similarity index value of species between harvested and non-harvested sites was close to each other. Soil bulk density and soil hardness were increased after timber harvesting, respectively. The level of organic matter, total-N, avail $P_2O_5$, CEC($K^+$, $Na^+$, $Ca^{{+}{+}}$, $Mg^{{+}{+}}$) in the harvested area were found decreased. While the population of Colembola spp., and Acari spp. among soil mesofauna in harvested sites increased by two to seven times compared to those of non-harvested sites during the first year, the rates of increment decreased in the second year. However, those members of soil mesofauna in harvested sites were still higher than those of non-harvested sites in the second year. The results of statistical analysis using the stepwise regression method indicated that the diversity of soil mesofauna were significantly affected by soil moisture, soil bulk density, $Mg^{{+}{+}}$, CEC, and soil temperature at soil depth of 5(0~10)cm in the order of importance. The amount of surface water runoff on harvested sites was larger than that of non-harvested sites by 28% in the first year and 24.5% in the second year after timber harvesting. The level of BOD, COD, and pH in the stream water on the harvested sites reached at the level of the domestic use for drinking in the first and second year after timber harvesting. Such heavy metals as Cd, Pb, Cu, and organic P were not found. Moreover, the level of eight factors of domestic use for drinking water designated by the Ministry of Health and Welfare of Korea were within the level of the first class in the quality of drinking water standard. The study also showed that the amount of hillslope erosion in harvested sites was 4.77 ton/ha/yr in the first year after timber harvesting. In the second year, the amount decreased rapidly to 1.0 ton/ha/yr. The impact of logging on hillslope erosion in the harvested sites was larger than that in non-harvested sites by seven times in the first year and two times in the second year. The above results indicate that the large-scale timber harvesting cause significant changes in the environmental factors. However, the results are based on only two-year field observation. We should take more field observation and analyses to increase understandings on the impacts of timber harvesting on environmental changes. With the understandings, we might be able to improve the technology of timber harvesting operations to reduce the environmental impacts of large-scale timber harvesting.

• Journal of the Korean Institute of Landscape Architecture
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• v.17 no.3
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• pp.21-34
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• 1990

Trail and campground deteriorations and their environmental changes of soil and vegetation were studied in Tonghwa -Sa district of Mt. Palgong Natural Park through 1988 into 1989. The results are summarized as follows : 1. The bare width of trail as one of the trail condition factor was significantly greater on the more heavily used trail. Deterioration types of trail which had higher frequency for a total of 45 observations were rock exposure(42%), trail deepening(40%) and root exposure(18%) in the high order. And also sound type on which the trail was not deteriorated at all amounted to 33% of all observations. 2. Ecological changes of soil and vegatation of trailsides were not found at a uniform tendency except that soil hardness was slightly decreased from trail edge to the forest, but they could be grouped by the type of user\`s behavior and site conditions. Use impacts on the natural environment of trailside in Mt. Palgong are still far from the severe harmulness. 3. Worse damages to compground condition were appeared in Bawi-gol than Susu-gol campsite. Types of mechanically damaged trees were tree with exposed root(63% ), scared tree(43% ), mutilated tree(30 % ) and felled tree in highly frequent order. And diameter increments of trees in campsites were oppressed by the campers. 4. Tree damage types and their frequencies could be basic as a means of which grasp the bounds of user's impacts. User's disturbance on campsite extended to the distance of 70∼90m from the core of campsite at Pawi-gol and 20∼30m at Susu-gol respectively. As the tolerant trees to use impact, Lespedeza maximowiczii, Rhus trichocarpa, Acer palmatum, Rubus crataegifolius and Celastrus orbiculatus were considered.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.3
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• pp.1-20
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• 2023

The present study has monitored the changes in the biodiversity of Dunchon-Dong ecological and landscape conservation area after the restoration of the wetland, identified and analyzed the threats to the ecosystem, and presented a management plan accordingly. In this area which was forests and rice paddies in the past, apartment reconstruction is currently underway, with some hinterland forests and wetlands remaining. When we look into the change in the floras, the total number of species was 193 in 2000 before the restoration, it decreased from 2004 to 2006, and as of 2019, it was 149, showing an increasing trend. The result of comparing the species that emerged before and after the restoration showed an increase in Cyperaceae herbs such as Carex maximowiczii and Carex dispalata growing in wetland areas within forests and Schoenoplectiella juncoides and Schoenoplectus tabernaemontani growing in areas within wetlands where shallow water is maintained. As a result of analyzing the change in the area ratio of each type of extant vegetation, the wetland native herbs formed the power at the highest ratio after the restoration. The change in the power of the wetland native herbs was on an increasing trend until 2007, after which it decreased much in 2010 and then gradually increased, showing values of 26.6% in 2000, 44.6% in 2002, 49.0% in 2005, 53.3% in 2007, 28.7% in 2010, and 37.3% in 2019. The cause of the decrease in 2010 was judged to be due to the vegetation management conducted to secure open water and remove organic matter in freshwater reservoirs. The amphibia which emerged from 2000 to 2019 was a total of 9 species including Hynobius leeshii, Bufo gargarizans, Kaloula borealis, and Rana uenoi. As a result of the changes in the emerging wild birds, the species diversity index before the restoration was 0.9922 in 2000, and the species diversity index after the restoration gradually increased to 1.2449 in 2005, 1.2467 in 2010, and 2.2631 in 2019. The amphibia and wild birds inhibiting in the Dunchon-Dong forest and wetland were judged to have increased through continuous wetland maintenance such as naturalized plant removal management, native plant maintenance, and open water securing management. For the ecosystem preservation management of the Dunchon-Dong ecological and landscape conservation area, it was suggested to minimize the impact of the Dunchon-Dong reconstruction project, reorganize the indiscriminate access roads adjacent to the wetland, and reorganize the main entrance to the wetland. For ecosystem restoration management, systematic restoration and ecological buffer planting were suggested to be carried out at the time of construction fence demolition.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.196-206
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• 2012

Studies of seasonal changes in $C_3/C_4$ mixed communities are rare, particularly in Asian summer monsoon climate zones. In our present study, seasonal changes in the profile and coverage of $C_3$ and $C_4$ plants were investigated in 2009 in Haenam, Yeongdong and Cheorwon regions of South Korea (all at different latitudes). The aim was to estimate the impacts of temperature and sunshine duration on species composition and transition timing of the $C_3$ and $C_4$ plants. From our results, the number of $C_3$ plants was found to increase from early spring to mid-May, and then decrease again until September in the Haenam and Yeongdong regions, but continuously increase from early spring to September in the Cheorwon region under relatively low summer temperatures. On the other hand, the number of $C_4$ plants increased from June or July to September in all three regions. These seasonal changes in species number and ratio have a direct impact upon species diversity which is highest when there are no dominant species. The relative coverage and relative summed dominance ratio (SDR') of the $C_3$ plants decreased from spring to autumn, but increased for the $C_4$ plants during this time in an exponential fashion with increasing accumulated temperature and sunshine duration. The transition timing from $C_3$ to $C_4$ plants occurred when the sum of sunshine duration for the days with daily mean temperature above $5^{\circ}C$ was 1017 hrs for the SDR'.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.1009-1029
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• 2023

Urban trees play a vital role in urban ecosystems,significantly reducing impervious surfaces and impacting carbon cycling within the city. Although previous research has demonstrated the efficacy of employing artificial intelligence in conjunction with airborne light detection and ranging (LiDAR) data to generate urban tree information, the availability and cost constraints associated with LiDAR data pose limitations. Consequently, this study employed freely accessible, high-resolution multispectral satellite imagery (i.e., Sentinel-2 data) to estimate fractional tree canopy cover (FTC) within the urban confines of Suwon, South Korea, employing machine learning techniques. This study leveraged a median composite image derived from a time series of Sentinel-2 images. In order to account for the diverse land cover found in urban areas, the model incorporated three types of input variables: average (mean) and standard deviation (std) values within a 30-meter grid from 10 m resolution of optical indices from Sentinel-2, and fractional coverage for distinct land cover classes within 30 m grids from the existing level 3 land cover map. Four schemes with different combinations of input variables were compared. Notably, when all three factors (i.e., mean, std, and fractional cover) were used to consider the variation of landcover in urban areas(Scheme 4, S4), the machine learning model exhibited improved performance compared to using only the mean of optical indices (Scheme 1). Of the various models proposed, the random forest (RF) model with S4 demonstrated the most remarkable performance, achieving R² of 0.8196, and mean absolute error (MAE) of 0.0749, and a root mean squared error (RMSE) of 0.1022. The std variable exhibited the highest impact on model outputs within the heterogeneous land covers based on the variable importance analysis. This trained RF model with S4 was then applied to the entire Suwon region, consistently delivering robust results with an R² of 0.8702, MAE of 0.0873, and RMSE of 0.1335. The FTC estimation method developed in this study is expected to offer advantages for application in various regions, providing fundamental data for a better understanding of carbon dynamics in urban ecosystems in the future.