- KOREAN
- P-ISSN2287-8327
- E-ISSN2288-1220
- SCOPUS, KCI
ISSN : 2287-8327
Vol.44 No.2
Abstract
Understanding vegetation structure and the relationship with environmental factors has been crucial for restoration and conservation of riparian zones. In this study, we conducted field survey in a riparian zone of Namhan River in South Korea both before and after flooding in order to understand temporal and spatial variations of riparian vegetation. There were significant temporal and spatial variations in species composition, and distribution patterns of vegetation were different along a gradient of elevation above the water level. At low elevation, Zizania latifolia was dominant throughout the field survey periods, and Bidens frondosa began to grow late and dominated both in post-flooding 1 and 2. Prior to flooding, Scirpus radicans and Polygonum thunbergii were widely distributed at middle elevation, while Artemisia vulgaris, Phragmites australis, and Miscanthus sacchariflorus were dominant at high elevation. After flooding, P. thunbergii was dominant at middle elevation with most other species decreasing, and more invasive or pioneer plants, including Artemisia princeps, H. scandens, and Sicyos angulatus, were observed at high elevation. Species composition and distribution patterns were homogeneous at low elevation, whereas dynamic variations of vegetation were observed both temporally and spatially at higher elevations. Elevation and distance from the water front were the most principal factors governing vegetation structure. Furthermore, soil physicochemical properties were also found to determine species composition and distribution patterns. These results indicate that vegetation structure in the riparian zones is formed by the combined effects of hydrological regime and soil physicochemical properties, inherent characteristics of species, and interspecific competition. Understanding of temporal and spatial variations of riparian vegetation may provide useful insights into ecological restoration and conservation of the vegetation within the riparian zones.
Abstract
Background: Antibiotics are widely used to treat animals from infections. After fertilizing, antibacterials can remain in the soil while adversely affecting the soil microorganisms. The concentration of oxytetracycline (OTC) in the soil and its effect on the soil microbial community was assessed. To assess the impact of OTC on the soil microbial community, it was added to the soil at concentrations of 50, 150, and 300 mg kg–1 and incubated for 35 days. Results: The concentration of OTC added to the soil decreased from 150 to 7.6 mg kg–1 during 30 days of incubation, as revealed by LC-MS. The deviations from the control values in the level of substrate-induced respiration on the 5th day of the experiment were, on average, 26, 68, and 90%, with OTC concentrations at 50, 150, and 300 mg kg–1, respectively. In samples with 150 and 300 mg kg–1 of OTC, the number of bacteria from the 3rd to 14th day was 2–3 orders of magnitude lower than in the control. The addition of OTC did not affect the fungal counts in samples except on the 7th and 14th days for the 150 and 300 mg kg–1 contaminated samples. Genes tet(M) and tet(X) were found in samples containing 50, 150, and 300 mg kg–1 OTC, with no significant differences in the number of copies of tet(M) and tet(X) genes from the OTC concentration. Conclusions: Our results showed that even after a decrease in antibiotic availability, its influence on the soil microbial community remains.
Abstract
In the forest ecosystems, litterfall is an important component of the nutrient cycle that regulates the accumulation of soil organic matter (SOM), the input and output of the nutrients, nutrient replenishment, biodiversity conservation, and other ecosystem functions. Therefore, a profound understanding of the major processes (litterfall production and its decomposition rate) in the cycle is vital for sustainable forest management (SFM). Despite these facts, there is still a limited knowledge in tropical forest ecosystems, and further researches are highly needed. This shortfall of research-based knowledge, especially in tropical forest ecosystems, may be a contributing factor to the lack of understanding of the role of plant litter in the forest ecosystem function for sustainable forest management, particularly in the tropical forest landscapes. Therefore, in this paper, I review the role of plant litter in tropical forest ecosystems with the aims of assessing the importance of plant litter in forest ecosystems for the biogeochemical cycle. Then, the major factors that affect the plant litter production and decomposition were identified, which could direct and contribute to future research. The small set of studies reviewed in this paper demonstrated the potential of plant litter to improve the biogeochemical cycle and nutrients in the forest ecosystems. However, further researches are needed particularly on the effect of species, forest structures, seasons, and climate factors on the plant litter production and decomposition in various types of forest ecosystems.
Abstract
Background: Natural forests are generally considered to be less prone to biological invasions than other modified ecosystems, particularly when canopy cover is high. Few decades of management of degraded forests by local communities in Nepal has increased canopy cover and altered disturbance regimes. These changes might have reduced the abundance of invasive alien plant species (IAPS) in forests. To understand the status of IAPS in such forests, we studied two community managed Shorea robusta forests (Sundari and Dhusheri) of Nawalpur district in central Nepal. In these two forests, vegetation sampling was done using circular plots 10 m radius at forest edge, gaps, and within canopy. Variation of IAPS richness and cover across these microhabitats were compared, and their variation with tree canopy cover and basal area analyzed. Result: Altogether 14 IAPS were recorded in the study forests; among them Chromolaena odorata, Ageratum houstonianum, and Lantana camara had the highest frequency. Mikania micrantha was at the early stage of colonization in Sundari Community Forest (CF) but absent in Dhuseri CF. Both IAPS cover and richness was higher at forest edge and gap than in canopy plots and both these attributes declined with increasing canopy cover and tree basal area. Conclusion: The results indicate that increase in canopy cover and closure of forest gaps through participatory management of degraded forests can prevent plant invasions and suppress the growth of previously established IAPS in Shorea robusta forests of Nepal. This is the unacknowledged benefit of participatory forest management in Nepal.
Abstract
Background: The purpose of this study, mosquito forecast system implemented by Seoul Metropolitan city, was to obtain the mosquito prediction formula by using the mosquito population data and the environmental data of the past. Results: For this study, the mosquito population data from April 1, 2015, to October 31, 2017, were collected. The mosquito population data were collected from the 50 smart mosquito traps (DMSs), two of which were installed in each district (Korean, gu) in Seoul Metropolitan city since 2015. Environmental factors were collected from the Automatic Weather System (AWS) by the Korea Meteorological Administration. The data of the nearest AWS devices from each DMS were used for the prediction formula analysis. We found out that the environmental factors affecting the mosquito population in Seoul Metropolitan city were the mean temperature and rainfall. We predicted the following equations by the generalized linear model analysis: ln(Mosquito population) = 2.519 + 0.08 × mean temperature + 0.001 × rainfall. Conclusions: We expect that the mosquito forecast system would be used for predicting the mosquito population and to prevent the spread of disease through mosquitoes.
Abstract
Background: Determining patterns of habitat use is key to understanding of animal ecology. Approximately 1% of bird species use brood parasitism for their breeding strategy, in which they exploit other species’ (hosts) parental care by laying eggs in their nests. Brood parasitism may complicate the habitat requirement of brood parasites because they need habitats that support both their host and their own conditions for breeding. Brood parasitism, through changes in reproductive roles of sex or individual, may further diversify habitat use patterns among individuals. However, patterns of habitat use in avian brood parasites have rarely been characterized. In this study, we categorized the habitat preference of a population of brood parasitic lesser cuckoos (Cuculus poliocephalus) breeding on Jeju Island, Korea. By using compositional analyses together with radio-tracking and land cover data, we determined patterns of habitat use and their sexual and diurnal differences. Results: We found that the lesser cuckoo had a relatively large home range and its overall habitat composition (the second-order selection) was similar to those of the study area; open areas such as the field and grassland habitats accounted for 80% of the home range. Nonetheless, their habitat, comprised of 2.54 different habitats per hectare, could be characterized as a mosaic. We also found sexual differences in habitat composition and selection in the core-use area of home ranges (third-order selection). In particular, the forest habitat was preferentially utilized by females, while underutilized by males. However, there was no diurnal change in the pattern of habitat use. Both sexes preferred field habitats at the second-order selection. At the third-order selection, males preferred field habitats followed by grasslands and females preferred grasslands followed by forest habitats. Conclusions: We suggest that the field and grassland habitats represent the two most important areas for the lesser cuckoo on Jeju Island. Nevertheless, this study shows that habitat preference may differ between sexes, likely due to differences in sex roles, sex-based energy demands, and potential sexual conflict.