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Background: This study was undertaken to analyze the distribution and ecological characteristics of invasive alien plant species on Jeju Island, and to provide basic data for their management and control. Results: A field research was conducted at 436 locations on Jeju Island. The field research identified nine species of invasive alien species growing on Jeju Island. Based on the distribution pattern, Hypochaeris radicata L., Rumex acetosella, and Ambrosia artemisiifolia L. were found to be distributed horizontally throughout Jeju Island, with vertical growth in two or more vegetation zones, from warm temperate to the subalpine zone. Widely distributed species penetrate various habitats, such as grasslands, ranches, roadsides, farmlands, and empty lots, and have an immensely negative impact on the ecosystem, including declining biodiversity on Jeju Island. Paspalum distichum var. indutum Shinners, Paspalum distichum L., Solanum carolinense L., and Aster pilosus Willd. were distributed in some areas as a biased distribution species, whereas Lactuca scariola L. and Solidago altissima L. were found only in certain areas as centralized distribution species. Conclusions: The centralized distribution species and biased distribution species of the invasive plants in the ecosystem of Jeju Island should be physically eliminated, keeping in mind the short-and mid-term perspectives and monitoring, and by considering expansion of additional distribution areas. Due to limitations of physical/ chemical elimination, time, and cost, widely distributed species require to be eliminated and managed, mainly to restore the integrity of the ecosystem, by planting native species to reestablish the habitat.

We consider bit allocation for channel state information (CSI) feedback in coordinated beamforming (CB) systems. The optimization problem under consideration is to minimize the total transmission power subject to the target signal to interference and noise ratio (SINR) constraints. We obtain a suboptimal solution to the problem that provides closed-form expressions for the total feedback rate and the feedback rates of each user and its channels. The advantage of the proposed scheme over the methods with equally distributed feedback rates among the users and/or channels is demonstrated by computer simulation: the CB system employing the proposed scheme causes less outage with less transmission power.

Background: Cakile edentula (Bigelow) Hook. is a successful invader that has been propagating globally. In Korea, Cakile edentula was found in 2008 for the first time, in the east coast of Korean peninsula. Based on site surveys conducted thereafter, Cakile edentula has propagated in the east coast from Goseong to Jeongdongjin, Gangneung and in the west coast of city of Hwaseong of Gyeonggi-do Province, and Taeangun County of Chungcheongnam-do Province. Results: Cakile edentula has infiltrated into four different vegetation communities (syntaxa) (Calystegio soldanellae-Salsoletum komarovii Ohba, Miyawakiet Tx.1967; Elymo-caricetum Kobomugi Miyawaki 1967; Carex pumila; and Calystegia soldanella) belonging to phytosociological classes of saltwort (barilla) and coastal glehnia. Cakile edentula competes with dominant species such as the saltwort (barilla) and beach morning glory, causing qualitative changes in species composition. It also affects local ecosystems through its competition with indigenous species, causing destruction of the traditional landscape. Conclusions: However, competition of Cakile edentula with indigenous species and the resulting replacement of such species are limitedly reported. Potential competitors with Cakile edentula have not been found yet. In Northeast Asia, qualitative changes realized in local ecosystems due to invasion of Cakile edentula are significantly noticeable. These necessitate proper controls for this invasive alien species to protect and preserve coastal dune areas.

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