Effects of Strong Wind and Ozone on Localized Tree Decline in the Tanzawa Mountains of Japan

Suto, Hitoshi,Hattori, Yasuo,Tanaka, Nobukazu,Kohno, Yoshihisa Korean Society for Atmospheric Environment 2008 Asian Journal of Atmospheric Environment (AJAE) Vol.2 No.2

The numerical simulation of wind and ozone ($O_3$) transport in mountainous regions was performed with a computational fluid dynamics technique. A dry deposition model for $O_3$ was designed to estimate $O_3$ deposition in complex terrain, and the qualitative validity of the predicted $O_3$ concentration field was confirmed by comparison with observed data collected with passive samplers. The simulation revealed that wind velocity increases around ridge lines and peaks of mountains. The areas with strong wind corresponded well with the sites of tree decline at high altitudes, suggesting that it is an important factor in the localization of tree/forest decline. On the other hand, there is no direct relationship between forest decline and $O_3$ concentration. The $O_3$ concentration, however, tends to increase as wind velocity becomes higher, thus the $O_3$ concentration itself may be a potential secondary factor in the localized decline phenomena. While the diffusion flux of $O_3$ is not related to localized tree decline, the pattern of advection flux is related to those of high wind velocity and localized tree decline. These results suggest that strong wind with large advection flux of $O_3$ may play a key role in the promotion of tree/forest decline at high mountain ridges and peaks.

Experimental Studies on the Effects of Ozone on Growth and Photosynthetic Activity of Japanese Forest Tree Species

Masahiro Yamaguchi,Makoto Watanabe,Hideyuki Matsumura,Yoshihisa Kohno,Takeshi Izuta 한국대기환경학회 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.2

Ozone (O_3) is a main component of photochemical oxidants, and a phytotoxic anthropogenic air pollutant. In North America and Europe, the current concentration of O_3 has been shown to have significant adverse effects on vegetation. In this review, we summarize the experimental studies on the effects of O-3 on the growth and photosynthetic activity of Japanese forest tree species to understand the present knowledge and provide sound basis for future research toward the assessment of O_3 impacts on Japanese forest ecosystem. Since the 1990s, several Japanese researchers have conducted the experimental studies on the effects of ambient levels of O_3on growth and physiological functions such as net photosynthesis of Japanese forest tree species. Although the sensitivity to O_3 of whole-plant growth is quite different among the species, it was suggested that the current ambient levels of O_3 in Japan are high enough to adversely affect growth and photosynthetic activity of Japanese forest tree species classified into high O_3 sensitivity group such as Japanese beech. The N load to soil has been shown to reduce the sensitivity to O_3 of Japanese larch and increase that of Japanese beech. To establish the critical level of O_3 for protecting Japanese forest tree species, therefore, it is necessary to take into account the N deposition from the atmosphere. There is little information on the combined effects of O_3 and other environmental factors such as elevated CO_2and drought on growth and physiological functions of Japanese forest tree species. Therefore, it is necessary to promote the experimental study and accumulate the information on the combined effects of O_3and any other abiotic environmental factors on Japanese forest tree species.

A Case Study of Risk Assessment of Ozone Impact on Forest Tree Species in Japan

Makoto Watanabe,Masahiro Yamaguchi,Hideyuki Matsumura,Yoshihisa Kohno,Takayoshi Koike,Takeshi Izuta 한국대기환경학회 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.4

Ozone (O_3) is a main component of photochemical oxidants and a phytotoxic air pollutant. Although the current levels of tropospheric O_3 in East Asia could adversely affect productivity of forest tree species,risk assessments of O_3 impact were limited. In this paper, we summarize the methodology of risk assessment of O_3 on forest tree species based on our two previous studies, risk assessments of O_3 impact on the growth of Fagus crenata by Watanabe et al. (2012) and on the annual carbon absorption of three representative conifers, Cryptomeria japonica, Pinus densiflora and Larix kaempferi by Watanabe et al. (2010). O_3 sensitivity of each tree species obtained from an experimental study, O_3 exposure and atmospheric N deposition based on field monitoring and vegetation survey were integrated by geographic information system method. Based on the results, we conclude that the area with high risk of O_3 impact does not necessarily correspond to the area with high O_3 exposure. The varieties of tree habitat, tree sensitivity to O_3 and annual carbon absorption among the tree species, and N deposition-induced change in the O_3 sensitivity of F. crenata are raised as the factors of discordance between areas with high risk and those with high O_3 exposure. In the last part of this paper, we discuss the present uncertainty and perspectives of risk assessment for the future studies on the impact of O_3 on forest tree species in East Asia.

A Case Study of Risk Assessment of Ozone Impact on Forest Tree Species in Japan

Watanabe, Makoto,Yamaguchi, Masahiro,Matsumura, Hideyuki,Kohno, Yoshihisa,Koike, Takayoshi,Izuta, Takeshi Korean Society for Atmospheric Environment 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.4

Ozone ($O_3$) is a main component of photochemical oxidants and a phytotoxic air pollutant. Although the current levels of tropospheric $O_3$ in East Asia could adversely affect productivity of forest tree species, risk assessments of $O_3$ impact were limited. In this paper, we summarize the methodology of risk assessment of $O_3$ on forest tree species based on our two previous studies, risk assessments of $O_3$ impact on the growth of Fagus crenata by Watanabe et al. (2012) and on the annual carbon absorption of three representative conifers, Cryptomeria japonica, Pinus densiflora and Larix kaempferi by Watanabe et al. (2010). $O_3$ sensitivity of each tree species obtained from an experimental study, $O_3$ exposure and atmospheric N deposition based on field monitoring and vegetation survey were integrated by geographic information system method. Based on the results, we conclude that the area with high risk of $O_3$ impact does not necessarily correspond to the area with high $O_3$ exposure. The varieties of tree habitat, tree sensitivity to $O_3$ and annual carbon absorption among the tree species, and N deposition-induced change in the $O_3$ sensitivity of F. crenata are raised as the factors of discordance between areas with high risk and those with high $O_3$ exposure. In the last part of this paper, we discuss the present uncertainty and perspectives of risk assessment for the future studies on the impact of $O_3$ on forest tree species in East Asia.

Genome-wide mapping of the ozone-responsive transcriptomes in rice panicle and seed tissues reveals novel insight into their regulatory events.

Cho, Kyoungwon,Shibato, Junko,Kubo, Akihiro,Kohno, Yoshihisa,Satoh, Kouji,Kikuchi, Shoshi,Agrawal, Ganesh Kumar,Sarkar, Abhijit,Rakwal, Randeep Kluwer Academic Publishers 2013 Biotechnology letters. Vol.35 No.4

<P>The 'ozone (O3)-responsive transcriptome' behavior in the panicles and grains of rice plant was studied individually through high-throughput oligo-DNA microarray technique. O3 differentially and separately regulated 620 and 130 genes in the panicles and grains. Among the O3-responsive genes, 176 and 444 genes were up- and down-regulated in panicle compared to 24 and 106 genes in grain, respectively. Further mapping revealed that the majority of differentially expressed genes were mainly involved in signaling, hormonal, cell wall, transcription, proteolysis, and defense events. Many previously unknown O3-responsive novel genes were identified. Inventory of 745 O3-responsive genes and their mapping will expand our knowledge on novel regulatory processes in both panicles and grains of rice; and, serve as a resource towards the designing of rice crops for future high-O3world.</P>

Comparative analysis of seed transcriptomes of ambient ozone-fumigated 2 different rice cultivars

Cho, Kyoungwon,Shibato, Junko,Kubo, Akihiro,Kohno, Yoshihisa,Satoh, Kouji,Kikuchi, Shoshi,Sarkar, Abhijit,Agrawal, Ganesh Kumar,Rakwal, Randeep Informa UK (Taylor Francis) 2013 Plant signaling & behavior Vol.8 No.11

Elevated CO₂ Could Reduce Spikelet Fertility and Grain Appearance Quality of Rice (Oryza sativa L.) Grown under High-temperature Conditions

Masahiro Yamaguchi,Shoma Kamiya,Dai Kokubun,Tomoki Nakayama,Tetsushi Yonekura,Yoshihisa Kohno KOSAE·JSAE·CSES-CSAE 2022 Asian Journal of Atmospheric Environment (AJAE) Vol.16 No.3

Two Japanese rice cultivars with different heat-tolerance, Hinohikari (sensitive) and Nikomaru (tolerant), were grown in pots inside open-top chambers and exposed to ambient CO₂ (400 μmol mol<SUP>-1</SUP>) or elevated CO₂ (550 μmol mol<SUP>-1</SUP>) from the beginning of the tillering stage to maturity. The study was conducted in Nagasaki, in the Kyushu region of Japan, where heat stress on rice has become increasingly evident. Although elevated CO₂ significantly improved the net photosynthesis and whole-plant growth of the cultivars, there were no significant effects on grain yield, which in turn reduced harvest index. In both cultivars, adverse effects occurred with elevated CO₂, such as reductions in spikelet fertility and grain appearance quality, which are typical manifestations of heat stress in rice. During the flowering period, the air temperature was high that spikelet fertility was reduced even under ambient CO₂ conditions for both cultivars. These results suggest that, under high-temperature conditions, elevated CO₂ could induce or exacerbate the manifestations of heat stress in rice. Because transpiration rate in the flag leaf was significantly reduced by the exposure to elevated CO₂, it is possible that elevated CO₂ increased plant temperature via a reduction in transpiration during flowering period, although we did not detect significance of the increase in leaf and panicle temperature. To ensure a more confident conclusion, further studies focusing on the effects of elevated CO₂ on the determinants of spikelet fertility and grain appearance quality with other cultivars in different year are required.

Combined effects of elevated air temperature and CO2 on growth, yield, and yield components of japonica rice (Oryza sativa L.)

Masahiro Yamaguchi,Nobuyuki Tazoe,Tomoki Nakayama,Tetsushi Yonekura,Takeshi Izuta,Yoshihisa Kohno 한국대기환경학회 2023 Asian Journal of Atmospheric Environment (AJAE) Vol.17 No.1

In the region where heat stress has become evident, the elevation of air temperature could reduce yield of heat stress-susceptible crops, such as rice (Oryza sativa L.), which is a major food staple in Asia. In addition to air temperature, atmospheric CO2 is projected to be elevated in the future. To project rice yield in the future, it is necessary to clarify the responses of rice to concurrent elevations of air temperature and atmospheric CO2. In the present study, two japonica rice cultivars with different heat tolerance, Hinohikari (sensitive) and Nikomaru (tolerant), were grown in pots inside open-top chambers and exposed to elevated air temperature and/or CO2. The degrees of increase in the air temperature and CO2 concentration by the treatments were approximately 1 °C and 120 μmol mol− 1 (ppm). The study was conducted in Nagasaki, Japan, where heat stress on rice has become evident. Elevated air temperature significantly decreased both whole-plant growth and grain yield. Elevated CO2 significantly increased the growth but significantly decreased the yield. The effects of elevated air temperature and elevated CO2 on growth and yield did not significantly differ between two cultivars. In both cultivars, the main cause of yield reduction by both treatments was reduction in spikelet fertility, which is typical heat stress on rice. The elevated CO2- induced reduction in spikelet fertility could be explained partially by high-temperature regime during flowering due to acceleration of heading and by increase in canopy temperature via stomatal closure in flag leaves. Because elevated air temperature and elevated CO2 treatments additively reduced spikelet fertility in both cultivars, concurrent elevations of air temperature and CO2 caused considerable reduction in grain yield.