Chang-Young Oh

Photosynthetic Inhibition in Leaves of Ailanthus altissima under O 3 Fumigation

We investigated the enect of on the photosynthetic characteristics of tree of heaven (Ailanthus altissima) that is naturalized plant and used as restoration plant for contaminated area. Two-year-old seedlings were planted to pots and transferred into closed chamber. Photosynthetic pigments contents and photosynthetic characteristics were measured every three weeks under 100 pub fumigation. There was no visible foliar injury by exposure and contents of photosynthetic pigments did not show significant differences between control and -treated seedlings. Also there were no significant differences in stomatal conductance, and water use efficiency. But photosynthetic rate and apparent quantum yield (AQY) of treated seedlings were reduced after nine weeks of ozone fumigation. In addition, the reduction of carboxylation efficiency and photorespiration were observed in the leave of treated seedlings after six weeks. In accordance with our result, carbon fixation system of A. altissima was most sensitive to stress to evaluate physiological damage induced by .

Photosynthetic Responses of Populus alba×glandulosa to Elevated CO 2 Concentration and Air Temperature

This study was conducted to investigate the photosynthetic characters of Populus alba×glandulosa cuttings in response to elevated CO2 concentration and air temperature for selecting tree species adaptive to climate change. The cuttings were grown in environment controlled growth chambers with two combinations of CO2 concentration and air temperature conditions: (i) 22 C + CO2 380 μmol mol (control) and (ii) 27C + CO2 770 μmol mol −1 (elevated) for almost three months. The cuttings under the elevated treatment showed reduced tree height and photosynthetic pigment contents such as chlorophyll and carotenoid. In particular, the elevated treatment resulted in a marked reduction in the chlorophyll a closely associated with CO2 fixative reaction system. Different levels of reduction in photosynthetic characters were found under the elevated treatment. A decrease was noted in photochemical reaction system parameters: net apparent quantum yield (7%) and photosynthetic electron transport rate (14%). Moreover, a significant reduction was obvious in CO2 fixative reaction system parameters: carboxylation efficiency (52%) and ribulose-1,5-bisphosphate(RuBP) regeneration rate (24%). These results suggest that the low level of photosynthetic capacity may be attributed to the decreased CO2 fixative reaction system rather than photochemical reaction system.

Effects of Elevated CO 2 Concentration on Leaf Phenology of Quercus acutissima

Effects of elevated CO2 on leaf phenology of Quercus acutissima were examined using open-top chambers, which had ambient and elevated CO2 concentrations (ambient × 1.4, ambient × 1.8). To analyze the effect of chamber, non-treatment block was established near outside of the chambers. In 2013, budburst, leaf unfolding, coloring, and shedding were surveyed, and spring phenology was surveyed in 2014. Thermal sum (base temperature +5 o C) of each phenological event occurred was recorded. In addition, bud samples were collected and analyzed for carbohydrate contents in March 2014. Elevated CO2 concentration advanced budburst and leaf unfolding, and delayed shedding in 2013. However, in 2014, the temperature of the spring season was high, and there was no significant effect of elevated CO2 concentration on spring phenology. Carbohydrates content, such as starch, total non-structural carbohydrate and total soluble sugar, were significantly increased in response to elevated CO2 concentration. It has been proposed that elevated CO2 concentration could extend the growing season of temperate species with increased possibility of frost damage due to early bud opening and leaf unfolding. However, our analysis showed that the increased carbohydrate concentration in bud under elevated CO2 would reduce the possibility of early spring frost damage by acting as cryoprotectant.

A Study on Ecological Niche of Pinus densiflora Forests according to the Environmental Factors

This study was conducted to investigate the effect of ecological factors affecting Pinus densiflora forest distribution associated with climate change in the future. Ecological niche is used as a method to quantify the position occupied in biological communities, space, influence and all ecological factors. Ecological niche breadth was analyzed on meteorological and growth factors of P. densiflora. Nine sites (i.e., Gangneung, Jeongseon, Pyeongchang, Hamyang, Bonghwa, Yeongyang, Uljin, Uiseong and Boseong) were selected to set 20 m × 20 m quadrat from September to October 2010. The height, DBH, clearlength, crown width and basal area were measured at each quadrat and used as growth factors. In addition, the measured values from the closest weather stations of each survey area of the maximum, mean and minimum temperature, humidity and precipitation were used as meteorological factors. The ecological niche breadth of the five meteorological factors except humidity was low. It is considered that precipitation could effect on the distribution of P. densiflora forest. In particular, maximum temperature showed low ecological niche breadth less than 0.4 in most of the survey areas. However, the ecological niche breadth of the five growth factors was high in all survey areas.

Adaptation of Betula schmidtii Seedling in Coal-mine Field with Different Sewage Sludge Treatment Methods

We tested the field adaptation of Betula schmidtii on the abandoned coal-mine soil with sludge amendment methods for promoting physiological activity of B. schmidtii seedlings under several environmental stress. Sewage sludges were amended to coal-mine soil with B. schmidtii seedlings which grown in the mixture of artificial soil and composted sludge soil before transplanting (before-fertilized treatment, BF) and fertilized with composted sludge after transplanting (after-fertilized treatment, AF). The percent of establishment of seedlings for AF (80.7%) was lower than that for BF (92.7%). Nitrate reductase activity and photosynthetic pigment content were higher in AF than in BF, but malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were lower in AF than in BF These results represent that after-fertilized seedlings increase resistance against physiological stress at field condition using nitrogen source of composted sludge. On the contrary, before-fertilized seedlings were susceptible to environmental stress on abandoned coal-mine soil by exhausting of nitrogen source from composted sludge.