Intermediate disturbance hypothesis is one of important hypotheses for presenting the diversity patterns under disturbances. To investigate the diversity patterns of benthic macroinvertebrate communities under various disturbances, we collected macroinvertebrates in 47 sites representing various habitat types as well as pollution gradients in Southeastern Korea in summer and winter. Environmental variables such as depth, velocity, substrate and conductivity, and biological water quality indices (e.g., BWMP) were measured to show the intensity of disturbance in each site. Species abundance distributions (SADs) which are one of the efficient ways to assess community structure states based on macroecology were also considered to represent the pollution status based on the community patterns along an established pollution gradient. The community patterns were broadly divided into log-normal distribution and geometric series groups according to SAD models with weak and strong disturbance, respectively. According to the application of physicochemical water quality variable (conductivity), the gradient of community indices showed higher values on the intermediate disturbance state. Higher values of community indices, however, were presented on the low disturbance state with the gradient from BMWP. The parameters of SAD models, log-normal distribution, γ, and geometric series, k, were additionally calculated and compared with the traditional community indices.

Distribution and abundance of species are influenced by their environmental condition. Among various environmental factors, a vegetation is one of the most influential factors, because it is used as habitats as well as food resources. Arthropods including insects play a important role in forest ecosystems as grazers, scavenger, predators, etc. Deciduous and coniferous forests have different plant community composition, resulting in different environmental condition. In this study, we collected arthropod communities at two different deciduous and coniferous forest stands in the Mountain Gariwang. At each stand, three different sampling methods were used: soil core for soil macroinvertebrate, pitfall trap for wandering insects, and sweeping net for insects in the shrups. Therefore, sampling was conducted at vertical habitats in the forest. The results showed that there were no difference in the number of orders from soil at both coniferous and deciduous stands. However, the abundance was higher at coniferous stand than at deciduous stand. Collembola was the dominant taxa in soil. Meanwhile, there were no statistically significant differences of community composition between coniferous stand and deciduous stands. Multivariate analyses was conducted to characterize differences of communities at different stands as well as vertical distribution in forest.

In this study, we evaluated the temporal changes of water quality in the 90 reservoirs in Korea and the relationships between water quality and their environmental factors in the reservoirs for effective management of reservoirs. The majority of study reservoirs were categorized as the eutrophic state based on Carlson’s trophic index. Among 90 reservoirs, more than 55.0% were nutrient-rich based on TSITP in each month, where more than 50.0% were nutrient-rich based on TSIChl-a from June to November. Seasonal Mann- Kendall test was used to analyze temporal variation of water quality in the selected 60 reservoirs using monthly data from 2004 to 2008. The results showed that 27 (45.0%) reservoirs showed the improvement of water quality based on TP and Chl-a concentrations, while 14 (23.3%) and 11 (18.3%) reservoirs displayed the degradation of water quality based on TP and Chl-a concentrations, respectively. Meanwhile, a self-organizing map classified the study reservoirs into five groups based on differences of hydrogeomorphology (altitude, catchment area, bank height, lake age, etc.). Physicochemical factors and land use/cover types showed clear differences among groups. Finally, hydrogeomorphology of reservoirs were related to water quality, indicating that the hydrogeomorphological characters strongly affect water quality of reservoirs.

Distribution of aquatic organisms is governed by various environmental factors Hydromorphological characteristics which are heavily affected by heavy rains in stream are one of the fundamental factors to influence the distribution of aquatic organisms. In this study we evaluated the difference response of two aquatic species Chironomus yoshimatisui and Limnodrilus hoffmesteri habiting to changes of discharge due to heavy rains. We compared the differences in their resilience and recover to disturbances. Our results showed that after a heavy rain during the sampling periods, the proportion of macrosubstrate highly increased and was not recovered into the previous states. Nonmetric Multi-dimensional scaling based on Chironomidae and Oligochaeta biota well represented annual and seasonal differences with heavy rain effects. Random forest model showed that the abundance of C. yoshimatisui were mainly influenced by microsubstrate, precipitation and Reynolds number, whereas stream roughness, mesosubstrate and macrosubstrate much more influenced the abundance of L. hoffmesteri.

This study examined the effects of environmental factors on the abundance of black pine bast scale (BPBS), Matsucoccus thunbergianae Miller and Park, in coastal disaster prevention forest stands composed mostly of Japanese black pine. Geographical factors, soil conditions and forest stand conditions were measured to evaluate the hazard rating for the occurrence of BPBS from 35 plots in the coastal forest stands. To assess the hazard rating, a combination of a self-organizing map (SOM), which classified the samples according to their characteristics, and a random forest model, which predicted the probability of the occurrence of BPBS from SOM results, was used in this study. Our results showed that major factors determining the abundance of BPBS were climate, tree size, and tree health. BPBS was more common in low latitude coastal forests, suggesting that warmer conditions were favorable to BPBS population buildup. Tree size also influenced the abundance of BPBS, which was higher in forests composed of larger trees (greater DBH). Finally, BPBS was also more abundant in areas with high soil salinity and clay-loam soil, and north-facing slopes where tree vigor was lower.

Forest resource development including plantation and thinning has severely influenced on the forest ecosystems. In this study, we compared differences of soil invertebrate communities between a larch planted forest and a natural deciduous forest. Soil invertebrates were collected at 6 sampling sites in the natural deciduous forest and at 9 sampling sites in the larch planted forest in June and September, 2013. Each study site was set in 1 ha and soil samples were collected using a soil core (5.5 cm diameter and 4.5 cm height). After sampling soil invertebrates, the invertebrates were extracted using Tullgren extractor for 72 hours. In total, 1,194 individuals and 22 taxa of soil invertebrates were identified in this study. Among them, Collembola was the most dominant taxa (41% of abundance). Abundance of the larch planted forest was higher two times than that of the natural deciduous forest. The results of this study provide fundamental information on soil invertebrate fauna before the forest managements. In the further study, we will examine the effects of various types of forest management on the community of soil invertebrates.

This study was carried out to investigate the changes of guilds in benthic macroinvertebrate community in a undisturbed headwater stream. Samples were collected seasonally with a Surber sampler (30×30cm) at three different sampling sites (five replicates in each sampling sites) at Bongsunsa stream in Korean National Arboretum in Gyeonggi-do for 7 years from 2006 to 2012. Physicochemical environmental factors including discharge, water width, substrate composition, dissolved oxygen, pH and conductivity were also measured at each sampling sites. Changes of community indices and functional guilds such as functional feeding groups and trophic groups were evaluated in each sampling sites during study periods. In the samples, 84 species (9 order, 36 family) were identified, and Gammarus sobuegensis, Chironomidae spp, Ephemera strigata and Ecdyonurus kibunensis were dominant taxa. Considering the changes of functional feeding groups, shredder tended to decrease from upstream to downstream, whereas collector-gatherer and collector-filterer became higher. In addition, shredder was higher during autumn seasons. Self-Organizing Map was also applied to find out the temporal changes of benthic macroinvertebrate community composition, displaying the effects of seasonal variations in reference stream ecosystems.

This study was conducted to evaluate the seasonal changes of benthic macroinvertebrate communities in a reference stream as well as the effects of physicochemical environmental factors on benthic macroinvertebrate communities in a study stream. Benthic macroinvertebrates were sampled seasonally at five different sampling sites with five replicates at Changjeon stream in Mountain Gariwang from spring to winter in 2011. Physicochemical environmental factors (e.g., discharge, width, substrate, conductivity, dissolved oxygen, pH and water temperature) were measured at each sampling sites. Water quality factors such as conductivity, dissolved oxygen and pH were similar among the sampling sites, whereas hydrological factors including discharge and width tended to be higher from upstream to downstream. In substrate composition, the relative ratio of large substrate such as cobbles was higher in summer season. In macroinvertebrate samples, 79 species with 2 phylum, 5 order and 9 family were identified during the sampling periods. Gammarus sp. was higher in upstream (sites 1 and 2), whereas Chironomidae spp. tended to be higher in downstream. In functional feeding groups, shredder was higher in upstream, whereas predator and collector-gatherer were higher in downstream. The ratios of Gammarus sp. and Plecopetera were higher in summer. Nonmetric multidimensional scaling was applied to figure out the differences of macroinvertebrate communities during the survey periods, representing the seasonal changes as well as hydrological gradients.

Benthic macroinvertebrates were collected using the Surber sampler from streams in forest areas in Southern Korea in spring and summer. Self-Organizing Map (SOM) was utilized to reveal community patterns in response to natural and anthropogenic variability in different seasons. The gradient was mainly observed according to degree of pollution and altitude. Subsequently, community compositions reflected seasonality in less-polluted area, showing difference in functional feeding groups. Gatherer-collectors and filterer-collectors were abundantly collected in spring whereas scrapers and predators were sampled in a majority in late summer. Representative species groups were identified in different seasons. persistence in communities in response to natural and anthropogenic variability.

Pomacea canaliculata (golden apple snail) as an invasive species in Asia has become a serious agricultural pest, especially in young rice, and makes significant environmental changes resulting from the depletion of macrophytes in natural wetlands. Even though various environmental factors influence to growth rate, reproduction, survival and behavior in apple snail, water temperature is one of the overwhelming effect on freshwater snails in general. In this sense, the objective of this study was to examine the changes of individual behavior in the apple snail according to the temperature changes. The snails were acclimated at 25℃, and 9 behavior categories were examined in each temperature regime (25℃ to 30℃, 2 5℃ to 20℃, and 25℃ to 15℃) for three days. Autocorrelation function (ACF) was applied to characterize the presence or absence of periodic behaviors in apple snails. The snails’ behavior in the treatment of elevated temperature were irregularly fluctuated or decayed in most behavior categories. On the other hands, in decreasing temperature from 25℃ to 15℃, the snails were nonstationary, especially in clinging behavior. The snails showed periodicity and some of them were decayed in clinging behavior in temperature changing from 25℃ to 20℃.

Understanding population dynamics is an important issue in population ecology because it can provide insight into factors determining population behavior as well as providing guidelines for population management. Complex population dynamics generally result from the combined influences of both intrinsic and exogenous forces. Therefore suitable analyzing methods are needed. In this presentation, various time series analyses approaches such as autocorrelation, Fourier Transformation, Cross-correlation, synchrony etc. will presented to extract information embedded in the population data observed in agricultural and forest ecosystems.

The golden apple snail, Pomacea canaliculata, is a freshwater snail native to tropical and subtropical South America. The species was introduced into Korea as a human food source in 1983 and was first applied as a weed control agent for the paddy fields in 1992. As the snail is well known as an environmentally friendly biological control agent for weeds, the area of cultivation in which the golden apple snail is used for biological control has been enlarged substantially each year. Currently, the species is observed in open water courses. It is possible that the snail may overwinter in these open water courses and may become a serious pest, as is already the case in many Asian countries. In this study, we determined the status of the overwintering golden apple snail based on a literature survey and investigated the potential distribution area of the snail, as a result from global warming in Korea. The potential distribution area of the overwintering golden apple snail would be enlarged under the influence of global warming; ranging from 45.5% of South Korea’s land area in the 2020s to 88.4% in the 2080s.

상록 Sedum의 이용을 확대하고자 두께와 토양을 각각 달리 처리한 식생매트인 coir tape와 jute net를 이용하여 6품종(S. reflexum ‘Blue Spruce’, S. rupestre ‘Angelina’, S. sexangulare, S. sexangulare var. elatum, S. spurium ‘Atropurpureus’, S. takesimense)을 삽목하여 45일 후 생육을 조사하여 다음과 같은 결과를 얻었다. 모든 단용처리 조건 및 처리요인 간 상호작용에서 분지수 및 초장, 지상부 생체중은 유의한 차이(p<0.001)를 나타냈다. S. takesimense을 제외하고는 모든 처리조건에서 분지가 되지 않은 분지수는 품종 및 매트종류에 상관없이 모래보다 원예용 상토에서 2배 이상 높게 나타났다. ‘Angelina’를 제외하고는 품종별 초장은 상토를 처리한 5 mm coir tape에 가장 높았다. 생체중은 상토를 5 mm coir tape에 식재한 ‘Blue Spruce’가 13.19 g으로 가장 높았다. 매트별 실험에서는 전체적으로 품종에 관계없이 jute net보다 5 mm 두께의 coir tape에서 Sedum의 생육이 좋았다.

We've collected litter-dwelling predatory arthropods (spiders and carabid beetles) by using pitfall traps at four different fire intensity treatment areas (control, ground fire, canopy fire, and canopy fire with plantation) at four different regional areas in 2005. We analyzed the arthropod community structures with PC-Ord for the difference of arthropod community among the various fire intensity treatments and control. Our objective was to verify if there was any difference between fired areas and non fired area (control) and between canopy fire with plantation and canopy fire without plantation. From our arthropod community structures, we found there was distinct community composition difference between fired areas and non-fired area as well as between control and canopy fire treatment with plantation or non-plantation. However, we are not sure yet that there was any distinct difference between control and ground fire treatments. Our results from the multivariate analysis, Non-parametric Multidimensional Scaling ordination, could be relatively conclude that the main difference of arthropod community between fired areas and non-fired areal and canopy fire with plantation or non-plantation was caused from the difference of arthropod habitat pattern such as litter depth, litter volumem, CWD cover or volume, and et. al. When we compared to control and other treatments, we could also conclude that the canopy fire treatment with non-plantation was relatively closed to control than the canopy fire treatment with plantation.

Benthic macroinvertebrates were collected with a Surber sampler in streams across different levels of pollution in Korea. Abundance data in different species were analyzed according to the models used in species abundance distribution (SAD), covering geometric series, log series and log normal model. Different patterns in SADs were observed according to the states pertaining to the sample sites. While the log normal patterns were broadly applied to the collected samples, the other models (e.g., geometric series) were selectively observed. The slopes of rank abundance also accordingly reflected the degree of pollution. Application of the theoretical models was additionally discussed in revealing the states of communities. Efficiency of SADs was proposed in community monitoring in response to stressful conditions in aquatic ecosystems.