ng-Han You

Effects of elevated CO 2 concentration and increased temperature on leaf related-physiological responses of Phytolacca insularis (native species) and Phytolacca americana (invasive species)

In the study, the effects of elevated and temperature on the photosynthetic characteristics, chlorophyll content, nitrogen content, carbon content, and C/N ratio of Phytolacca insularis and Phytolacca americana were examined under control (ambient ambient temperature) and treatment (elevated elevated temperature) for 2 years (2008 and 2009). The photosynthetic rate, transpiration rate and water use efficiency of two plant species were higher under the treatment than the under the control. The stomatal conductance of P. insularis was higher under the control, but that of P. americana was not significantly affected by and temperature under the treatment. The chlorophyll contents of two species were decreased about 72.5% and 20%, respectively, by elevated and temperature. The nitrogen contents of two species were not significantly altered by increase in and temperature. The carbon contents of the two species were higher under the treatment than under the control. The C/N ratio of P. insularis was higher under the treatment but that of P. americana was not significantly affected by and temperature. These results demonstrated that the physiological responses of P. insularis native plants might be more sensitively influenced by a -mediated global warming situation than those of the P. americana invasive plants.

Evaluation of antidiabetic, antihyperlipidemic and antioxidant effects of Boehmeria nivea (L.) Gaudich., Urticaceae, root extract in streptozotocin-induced diabetic rats

The potential role of 80% methanolic extract of Boehmeria nivea (L.) Gaudich., Urticaceae, root in the treatment of diabetes, along with its antihyperlipidemic and antioxidant effects, was studied in streptozotocin-induced diabetic male Wistar rats. Preliminary screening of the extract revealed the presence of polyphenolics and flavonoids. The animal study was conducted with variable doses of 125, 250 and 500 mg/kg of extract for 21 days in diabetic rats. A significant effect was observed at a dose of 500 mg/kg, which was comparable to the standard drug, glibenclamide. Administration of the extract at a 500 mg/kg dose resulted in a significant reduction of fasting blood glucose, total cholesterol, triglycerides, blood urea, alanine aminotransferase, aspartate aminotransferase, urine sugar and urine ketone levels in diabetic rats in comparison with the diabetic control group. Additionally, this dose significantly increased body weight, hemoglobin, plasma total protein, high density lipoprotein cholesterol, liver glycogen content, superoxide dismutase, reduced glutathione and catalase levels in diabetic rats at the end of 21 days of treatment. Therefore, dietary supplementation with Boehmeria nivea root extract could be beneficial for correcting hyperglycemia, hyperlipidemia and enhancing the antioxidant defense system.

Measurement of ecological niche of Quercus aliena and Q. serrata under environmental factors treatments and its meaning to ecological distribution

Quercus aliena and Q. serrata are both occur as natural vegetation alongside natural freshwater bodies of the southern Korea Peninsula. Q. serrata dominates over Q. aliena as secondary forest vegetation in the present day. In order to explain these natural distributional traits of the oak species, we conducted some experiments with oak seedlings which treated with major important environmental resources, including light, moisture and nutrients, under controlled conditions. We then measured the ecological niche breadths and overlap from 15 eco-morphological characteristics. The ecological niche breadth of Q. aliena and Q. serrata were higher in terms of the nutrient factor applied, but was lower terms of light. The niche breadth of Q. serrata was wider than that of Q. aliena in light and moisture exposure. On the other hand, the niche breadth of Q. aliena was similar with that of Q. serrata in terms of the nutrient factor applied. These results imply that Q. serrata has a broader ecological distribution in over a wider variety of light and moisture environments than that of Q. alien. Ecological niche overlap between two oak species was the widest in terms of the light treatment factor applied, and narrowest in terms of moisture. This response pattern was also verified by cluster and principle component analysis. These results suggest competitive interactions between Q. serrata and Q. aliena seedlings may be higher for light resources than moisture or nutrient resources, and that Q. serrata is more shade tolerant than Q. aliena.

Aboveground biomass estimation of Quercus glauca in evergreen forest, Kotzawal wetland, Cheju Island, Korea

This study developed allometry equation and estimated the aboveground-biomass of Quercus glauca, a warm-temperature, evergreen broad-leaved tree, growing in Kotzawal wetland located on Jeju Island. The allometric equations between DBH(diameter at breast height) and dry weights of stems (Ws), branches (Wb), leaves (Wl) and aboveground biomass (Wab) of Q. glauca were as follows: logWs

Effects of Elevated CO 2 and Temperature on the Leaf Morphological Responses of Quercus serrata and Quercus aliena, Potential Natural Vegetation of Riverine

This study was conducted to find the leaf morphological responses of Quercus serrata and Q. aliena which are potential natural vegetation of riverine in Korea under elevated CO2 and increased temperature. Rising CO2 concentration was treated with 1.6 times than control(ambient) and increased temperature with 2.2℃ above the control(ambient) in the glass greenhouse. As a result, leaf width length, leaf lamina weight and leaf area of Q. serrata and Q. aliena was respectively increased, and number of leaves and specific leaf area(SLA) was decreased by elevated CO2 and temperature. Leaf width length, leaf lamina length, leaf lamina weight, number of leaves, leaf area, and specific leaf area of Q. serrata were not statistically significant difference between control and treatment. Leaf width length and leaf weight of Q. aliena was increased, but specific leaf area was decreased. These results indicated that Q. aliena was to be sensitive than Q. serrata in response to global warming situation. According to the principal component analysis(PCA), two oak species were arranged based on factor 1 and 2 in the control and warming treatment. And change on the warming treatment was clearly distinguishable from the Q. aliena than Q. serrata.

Ecophysiological responses of Quercus gilva, endangered species and Q. glauca to long-term exposure to elevated CO 2 concentration and temperature

The physiological effects of elevated CO 2 concentration and temperature were examined for Quercus gilva and Q. glauca grown under control (ambient CO 2 and temperature) and treatment (elevated CO 2 and temperature) conditions for 39 months. The objective of the study was to measure the long-term responses, in physiological parameters, of two oaks species exposed to elevated CO 2 and temperature. The photosynthetic rate of Q. gilva was found to be decreased, but that of Q. glauca was not significantly affected, after long-term exposure to elevated CO 2 and temperature. Stomatal conductance of Q. glauca was reduced by 21.7%, but that of Q. gilva was not significantly affected, by long-term exposure to CO 2 and temperature. However, the transpiration rate of the two oak species decreased. Water use efficiency of Q. gilva was not significantly affected by elevated CO 2 and temperature, while that of Q. glauca was increased by 56.6%. The leaves of Q. gilva grown under treatment conditions had an increased C:N ratio due to their reduced nitrogen content, while those of Q. glauca were not significantly affected by long-term exposure to elevated CO 2 and temperature. These results suggest that the long-term responses to elevated CO 2 and temperature between Q. gilva and Q. glauca are different, and that Q. gilva, the endangered species, is more sensitive to elevated CO 2 and temperature than Q. glauca.