• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.588-595
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• 2013

This study investigated the influence of temperature and $CO_2$ increase on phytoplankton growth and community structure during cold water season (spring) in Lake Paldang, Korea. Four experimental treatments of temperature and $CO_2$ manipulation were prepared in the laboratory batch culture: (1) Control; ambient low temperature ($6{\pm}2^{\circ}C$) and low $CO_2$ (air level, $400mgL^{-1}$), (2) T1; low temperature and high $CO_2$ ($800mgL^{-1}$), (3) T2; high temperature ($20{\pm}2^{\circ}C$) and low $CO_2$, (4) T3; high temperature and high $CO_2$. Algal growth experiment was carried out for 10 days under the light intensity of $70{\mu}mol\;m^{-2}s^{-1}$ (L :D=24 : 0). The level of pH decreased in both T1 and T3, due to dissolution of added $CO_2$. The dominant phytoplankton species of ambient water, Cyclotella meneghiniana succeeded to Fragilaria capucina var. gracilis in high-temperature treatment groups (T2 and T3). Cyanobacteria were very rare at the beginning of the experiment, while Oscillatoria limnetica appeared in only high-temperature groups (T2 and T3) at $6{\sim}7^{th}$ day. $CO_2$ addition in ambient temperature (T1) induced the highest phytoplankton growth, and thereby producing the highest average cell density of $3.27{\pm}0.33\;10^4\;cells\;mL^{-1}$, followed by T2 ($2.65{\pm}0.26\;10^4\;cells\;mL^{-1}$), T3 ($2.09{\pm}0.16\;10^4\;cells\;mL^{-1}$), and Control ($1.86{\pm}0.13\;10^4\;cells\;mL^{-1}$) (F=7.167, p=0.000). In summary, temperature increase changed the phytoplankton community structure and $CO_2$ increase promoted the phytoplankton growth during the cold spring season in Lake Paldang, suggesting a potential effect of climate change on freshwater phytoplankton.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.276-288
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• 2013

The present study investigates the effects of elevated soil nitrogen on growth and decomposition of Oryza sativa shoots. The plants were cultivated in greenhouse until leaf senescence and the total biomass of the plant increased 1.9 times at nitrogen addition plot. Total C and N content in shoot increased; however, lignin, C/N, and lignin/N levels decreased in the N-treated soil. The shoot litters collected from the control and N-treated soil were tested for decay and microbial biomass, $CO_2$ evolution, and enzyme activities during decomposition on the control and N-treated soil at $25^{\circ}C$ microcosm. The remaining mass of the shoot litter was approximately 6% higher in the litter collected from the control soil (53.0%) than the litter collected from high N-treated soil (47.1%). However, the high N-containing litter exhibited faster decay in the control soil than in the N-treated soil. The litter containing high N, low C/N, and low lignin/N showed a higher decomposition rate than that of low quality litter. The N-addition showed decreased microbial biomass C and dehydrogenase activity in soil; however, it exhibited high microbial biomass N and urease activity in soil. When the high N-containing litter decays on the N-treated soil, the microbial biomass C increased rapidly at the initial phase of decomposition and decreased thereafter, and dehydrogenase activity was less that of other treatment; however, there was no effect on the microbial biomass N. The urease in the decomposing litter was highest during the early decomposition stage and dramatically decreased thereafter. The present findings suggested that the N-addition increased N content in litter, but inhibited the decomposition process of above-ground biomass in terrestrial ecosystems.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.570-580
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• 2013

The forest vegetation of the Deogyusan National Park is classified into mountain forest vegetation and riparian forest vegetation. Mountain forest vegetation in the forest vegetation is subdivided into deciduous broad-leaved forest, valley forest, coniferous forest, subalpine coniferous forest, shrub forest, afforestation and other vegetation. Including 192 communities of mountain forest vegetation and 3 communities of other vegetation, the total of 195 communities were researched; the distributed colonies classified by physiognomy classification are 61 communities deciduous broad-leaved forest, 55 communities of valley forest, 17 communities of coniferous forests, 6 communities of subalpine coniferous forest, 3 communities of shrub forest, 50 afforestation and 3 other vegetation. As for the distribution rate for surveyed main communities, Quercus mongolica, Quercus serrata, Quercus variabilis communities account for 66.00 percent of deciduous broad-leaved forest, Fraxinus mandshurica, Cornus controversa community takes up 64.40 percent of mountain valley forest, Pinus densiflora community holds 70.40 percent of mountain coniferous forest holds. In conclusion, minority species consisting of Quercus mongolica, Quercus serrata, Quercus variabilis, Fraxinus mandshurica, Cornus controversa, Pinus densiflora are distributed as dominant species of the uppermost part in a forest vegetation of Geochilbong in Deogyusan National Park. In addition, because of vegetation succession and climate factors, numerous colonies formed by the two species are expected to be replaced by Quercus mongolica, Carpinus laxiflora and Fraxinus mandshurica which are climax species in the area. However, the distribution rate of deciduous broad-leaved forest seems to increase gradually due to global warming and artificial disturbance.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.561-569
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• 2013

This study examines locational environment factors that may affect the vegetation structure in the forests of Naejang National Park. To that end, we selected LAI (Leaf Area Index), diameter at breast height, and tree height as structural variables as well as altitude above sea level, gradient, slope direction, soil moisture, topographic location, and amount of solar radiation as locational environment factors, using the method of canonical correlation analysis in order to find out correlation between them. As to the simple correlation between the locational environment factors and structural variables, the correlation coefficient was relatively low (0.6). The values of LAI, measured along the ridge with higher altitudes, decreased as the soil moisture and solar radiation increased. However, LAI increased as the gradient increased and the slope direction faced the north (farther from the east). In respect of the diameter at breast height, the diameter decreased as the altitude and gradient increased. But the diameter increased as the moisture and solar radiation increased. The tree height decreased as the moisture increased and the site was closer to the ridge. These various correlations show a variety of locational environment factors in the national park, implying that the structural variables are affected by complex locational environment factors. This study conducted a canonical correlation analysis on locational environment factors which may affect the vegetation structure, and the result showed that LAI increased and tree height & diameter at breast height decreased as the solar radiation & moisture decreased and altitude increased. Although more factors that may affect vegetation structure (e.g. climate) should be taken into account, this study is significant in that the vegetation structure, which can adapt to more unfavorable conditions in terms of solar radiation, moisture, and higher altitudes, could be inferred in a statistical way. The results of this study, especially the locational environment factors based on DEM, can be used for assessing diversity of vegetation structure in a forest and for monitoring the structure in a national park on a regular basis so as to establish more effective maintenance plans of a park.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.289-300
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• 2013

Forest vegetation of Hyangjeokbong (1,614 m) in Deogyusan National Park is classified into mountain forest vegetation and flatland forest vegetation. Mountain forest vegetation is subdivided into deciduous broad-leaved forest, valley forest, coniferous forest, subalpine coniferous forest, shrub forest, grassland forest, afforestation and etc., while riparian forest was found under the category of flatland forest vegetation. Including 122 communities of mountain forest vegetation and 2 communities of riparian forest, the total of 124 communities were researched; the distributed colonies classified by physiognomy classification are 42 communities deciduous broad-leaved forest, 37 communities of valley forest, 8 communities of coniferous forests, 6 communities of subalpine coniferous forest, 3 communities of shrub forest, 1 communities of grassland forest, 21 afforestation and 4 other communities. As for the distribution rate for surveyed main communities, Quercus mongolica, Quercus serrata, Quercus variabilis communities account for 47.02 percent of deciduous broad-leaved forest, Fraxinus mandshurica community takes up 57.48 percent of mountain valley forest, Pinus densiflora community holds 77.53 percent of mountain coniferous forest holds, and Taxus cuspidate-Abies koreana community takes up about 50 percent of subalpine coniferous forest. Mountain shrub forest and mountain grassland forest vegetation are concentrated mainly on the top of Hyangjeokbong and the ridge connecting the top and Jungbong. Meanwhile, riparian forest vegetation comprises 0.024% of the whole vegetation area in a study area. In conclusion, minority species consisting of Quercus mongolica, Quercus serrata, Quercus variabilis, Fraxinus mandshurica, Cornus controversa, Pinus densiflora, Abies koreana and Taxus cuspidata are distributed as dominant species of the uppermost part in a forest vegetation region in Deogyusan National Park. In addition, because of vegetation succession and climate factors, numerous colonies formed by the two species are expected to be replaced by Quercus mongolica, Carpinus laxiflora and Fraxinus mandshurica which are climax species in the area. However, in respect of subalpine coniferous forest, the distribution rate of deciduous broad-leaved forest seems to increase gradually due to global warming and artificial disturbance.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.551-560
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• 2013

Environmental factors and epilithic diatom communities in the lower streams near the harbor region of South Korean peninsula were examined during no monsoon period in May 2013. The sampling of water and epilithic diatoms was conducted at both streams, 19 regulated streams (RS) that there are one or several dams constructed in the river system, and 19 un-regulated streams (US) that there are no dams within the river. A cluster analysis based on the number of species and abundance of epilithic diatoms through the stations, divided into three groups such as groups I (mainly US), II (mixed with US and RS) and III (mainly RS), respectively. Group I showed that water quality is good and high diversity of diatom, while Group II and III was water quality is relatively poor, but not differed in biomass of diatom from Group I. In addition, Group II that had high conductivity, nitrogen and phosphorus, was the lowest in diatom diversity among them. Dominant species were Nitzschia palea (17%) and Navicula seminuloides (11%) in Group I, Nitzschia inconspicua (19%) and Navicula perminuta (9%) in Group II, and Nitzschia inconspicua (15%) and Nitzschia palea (14%) in Group III, respectively. These taxa were widely distributed in brackish water, and not closely related with specific water quality, like eutrophic water. However, the groups II and III belonged to RS, had not only little biomass, but bad water quality such as high concentrations of nutrient and chlorophyll-a. Therefore, to determine the effect of dam construction on the lower water ecosystem, the planktonic algae, which can occur algal bloom in the estuary, also was considered to be a parallel investigation.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.524-540
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• 2013

After the construction of the Geum River estuary dam, we investigated the ecological property of phytoplankton community with physicochemical property in 9 stations of Geum River estuary 4 times seasonally in 2010 about the environmental changes through the change of phytoplankton. Physicochemical property seems to show eutrophication which developed from the tendency of accruing of the nutrients (those involved in intermittency of freshwater which flows from the dike and the surrounding cities), caused by the changing of tidal flow, the decreasing of the inflow of seawater after the construction of the Geum River estuary dam (dike). A total of 233 species of species composition of phytoplankton emerged, showing a highly increased result compared to that of the former research. The reason for the increase in number is considered as a phenomenon resulting from the mix of blackish and freshwater marine species in the flow of intermittency of freshwater discharge. Also, the standing crops of phytoplankton considerably increased compared to when the dike had not yet been built. Highly affected by the discharge of occasional freshwater, the diatoms of blackish water zone dominated in spring and winter, while freshwater species appeared to dominate in summer and autumn. The species diversity showed over 2.0 except in winter season. After a cluster analysis, the result showed that the Geum River estuary was influenced by runoff from cities like Gunsan, the sewage which flows from Gyeongpo River, and the intermittency of freshwater discharge from the Geum River estuary dam.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.461-474
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• 2005

Physicochemical parameters, plankton community structure, and sediment were surveyed from 1988 to 2002, at two months interval, in a eutrophic coastal lagoon (Lake Songji, Korea). The lake basin is separated from the sea by a narrow sand dune, and a shallow sill divides the lake basin into two sub-basins. The stable stratifications and chemoclines are maintained all through the year at 1-2 m depth. DO was often very low (<1 $mgO_2\;{\cdot}\;L^{-1}$) in the monimolimnion. Secchi disc transparency was in the range of 0.5-2.7 m. TP, TN, and Chl. a concentration in the mixolimnion were 0.015-0.396 $mgP\;{\cdot}\;L^{-1}$), 0.223-3.521 $mgN\;{\cdot}\;L^{-1}$, and 0.5-129.8 mg ${\cdot}\;m^{-3}$, respectively. TSI was in the eutrophic range of 54 to 62. Sediment was composed of silt and coarse silt. COD, TP, and TN content of the sediment were 51.4-116.9 $mgO_2\;{\cdot}\;gdw^{-1}$, 0.04-1.46 $mgP\;{\cdot}\;gdw^{-1}$ and, 0.12-1.03 $mgN\;{\cdot}\;gdw^{-1}$, respectively. The 49 phytoplankton species were identified. The maximum phytoplankton abundance obscured the lake in September 2001 (max. density: 23,350 cells ${\cdot}\;mL^{-1}$. The Chlorophyte Schroederia judayi was dominant species in summer (max. density: 20,417 cells ${\cdot}\;mL^{-1}$). The lake showed unique limnological features of a brackish lagoon in respect to biological community, chemical characteristics, and physical phenomena.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.482-493
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• 2005

The objective of this research was to evaluate an sampling effect of fish species and individual number on sampling techniques of electrofishing and conventional capture methods of cast net and kick net in 38 stream sites sampled during June - September, 2005. For the study, sampling gears were categorized as three types of electrofishing method (EM), conventional sampling technique (CM), and the combined technique (CT) of the electrofishing and the conventional method to compare statistical differences. Major differences of species composition between the CM and EM method were found in some benthic species of Misgurnus mizolepis and Iksookimia koreensis along with lithophilic species of Pungtungia herzi. These species were predominated in the EM rather than the CM, indicating that conventional sampling can underestimate the abundance of benthic or lithophilic species. In contrast ,individual number of typical water column species such as Zacco platypus and Zacco temmincki were more sampled by the CM, so that these fish populations were community overestimated. Also, t-tests on the types of sampling gear from various watersheds of Chogang Stream, Yugu Stream, Daejeon Stream, and Gap Stream showed that total individual numbers and species number in each stream were significantly (t values = 2.806-6.896, p values<0.05, n = 5-14) greater in the CT than the CM. Similar statistical significance (p<1.001, n = (10-24) on sampling seasons were observed during the monsoon and postmonsoon. These results indicate that if the electrofishing is not added to the conventional gears, the abundance of fish population and community can be underestimated and some benthic or lithophilic species may be excluded from the analysis, resulting in overall errors including sampling, fish fauna, and final judgement of community abundance. Overall our results strongly suggest that new application of electrofishing method along with the conventional sampling gears reduce sampling bias on underestimation of the real fish populations and communities.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.327-336
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• 2001

Physical, chemical, and biological parameters were measured during the period from July 1993 to August 1994 near the Munui intake tower of Taechung Reservoir to evaluate effects of nutrients and suspended solids on algal chlorophyll-a and water clarity. Large amounts of precipitation during summer 1993 produced minimum conductivity ($88\;{\mu}S/cm$), minimum TN : TP (<40), and maximum total phosphorus (TP;$59\;{\mu}g/L$) and resulted in a chlorophyll-a peak ($79\;{\mu}g/L$) and minimum transparency (<1.5 m) among the seasons. At the same time, ratios of volatile suspended solids (VSS): non-volatile suspended solids (NVSS) were maximum (13.0),indicating that the reduced transparency was mainly attributed to biogenic turbidity in relation to phytoplankton growth. In contrast, severe drought in summer 1994 resulted in greater conductivity (>$120\;{\mu}S/cm$), water clarity (%gt;2 m), and lower TP and chlorophyll- a (<$10\;{\mu}g/L$) relative to those of summer 1993. Total phosphorus ($R^2=0.46$, n=59) accounted more variations of chlorophyll- a compared to total nitrogen ($R^2=0,29$, n=59). The mass ratios of TN : TP ranged from 39 to 222 and were strongly correlated with TP (r = -0.80) but not with concentrations of TN (r = 0.05). Ambient nutrient concentrations and TN : TP mass ratios indicated that seasonality of chlorophyll- a was likely determined by concentrations of phosphorus reflected by the distribution of rainfall. It was concluded that reductions of phosphorus during heavy rainfall may provide better water quality for the drinking water in the intake tower.