Trace atmospheric gases in the biosphere, such as ozone (O3), nitrogen oxides (NOx), and biogenic volatile organic compounds (BVOCs), can affect the carbon cycle as well as the climate. Vertical profiles of nitric oxide (NO), O3, and volatile organic compound (VOC) concentrations were measured at a Japanese larch (Larix kaempferi) forest in the foothills of Mt. Fuji in Japan over an 11-day period in July 2012. The concentrations of NO and O3 during the day were highest above the canopy and decreased with proximity to the forest floor, but those of the VOCs had minimum and maximum points at different levels within the canopy depending on the species. Inverse multilayer models were applied to identify vertical sink and source distribution of these gases within the canopy. The model estimated that there was higher O3 deposition and absorption at the forest floor than in the canopy layer; therefore, the understory was an important O3 sink within the forest. A strong NO sink was simulated in the trunk space, where loss by reaction with O3 is expected. The sinks and sources of BVOC as well as their oxidized products are simulated in the canopy layer and the forest floor. The sink and source distribution suggested that VOC transportation from the neighboring forest also affected the vertical sink and source distribution within the canopy.
Nitrogen use efficiency (NUE), defined as the ratio of biomass growth and the nitrogen (N) taken up from a soil, is widely used in the evaluation of plant N economy. We conducted a fertilization experiment with Quercus serrata seedlings under different soil N and phosphorus (P) levels to determine the influence of high N deposition levels under different P availabilities upon NUE, plus the NUE components N productivity (NP), and mean residence time of N (MRT). The seedlings were grown for one growing season in the potted soil under three N levels (0, 50, and 100 kg N ha-1) combined with two P levels (0 and 50 kg P ha-1). Nitrogen supply to the soil reduced NUE by decreasing NP and MRT, whereas P supply enhanced NUE. Although P supply did not have a significant influence on the reduction of NUE with increasing N levels, it affected the response of the NUE components with increasing N levels. Within leaves, N supply reduced the photosynthetic nitrogen use efficiency (PNUE), P alleviated this reduction. Therefore, P is considered as one of the key factors determining the change of NUE in Q. serrata under the influence of high N supply.
In Asia, where rice is a major crop, there is high concern about the detrimental effects of climate change on rice productivity. Evaluating these effects, considering the country-specific cultivars’ responses to climate, is needed to effectively implement the national adaptation plans to maintain food security under climate change. However, to date, information on the effects of climate change on the local rice cultivars used in developing countries is extremely limited. In the present study, we used a process-based crop growth model, MATCRO-Rice, to predict the impact of climate change on yields of the major local rice cultivar Ciherang in Indonesia during the next 25 years (2018-2042). This model simulated the effects of current to future air temperature, precipitation, and atmospheric carbon dioxide concentration on rice yield. A total of 14 future climate scenarios, derived from a combination of four general circulation models and three or four representative concentration pathway scenarios in the Coupled Model Intercomparison Project Phase 5, were used to consider the uncertainty of the future climate. The results showed that the rice yield was reduced under all climate scenarios, mainly because of the higher air temperature, leading to reduced photosynthetic rates, increased respiration rates, and phenological changes such as acceleration of senescence. The mean yield reduction across the 14 future climate scenarios was 12.1% for all of Indonesia in 2039-2042. Therefore, to maintain yields in Indonesia, rice production needs to adapt to climate change, and especially to higher air temperatures, in the near future.
In recent years, peel puffing and delayed peel pigmentation have been observed in satsuma mandarins, possibly due to global warming. The effects of elevated temperatures during fruit maturation on fruit quality have been well studied. However, little is known about the effects of elevated temperatures during the flowering to physiological fruit drop stage. To clarify this, we controlled the air temperatures around satsuma mandarin trees during the flowering to physiological fruit drop stage (Period A) and at the fruit maturation stage (Period B). Temperatures were set to 2°C or 4°C above the recent mean temperatures because global warming is predicted to increase the mean global surface temperature by 2°C-4°C in this century. We then investigated the effects of the elevated temperatures on fruit quality in varying combinations for Periods A and B. Peel puffing was increased when temperatures were increased by 4°C during Period A or by 2°C or 4°C during Period B. Peel puffing was also increased with increases of 2°C during Period A; however, those results were not statistically significant. Peel pigmentation was enhanced when temperatures were increased by 2°C or 4°C during Period A but deteriorated when the temperature was increased by 2°C during Period B. Fruit weights were increased when temperatures were increased during Period A, but this was partly due to higher peel percentages. The peel percentages tended to be higher after temperature increases in either Period A or Period B. The soluble solid concentrations and acidity levels of the fruit juices tended to be lower after temperature increases during Period A, although not all of those changes were statistically significant. In conclusion, we found that temperature increases of 2°C or more above the recent mean temperatures during early fruit development can be detrimental to fruit quality by increasing peel puffing.
Monoterpenes and isoprene emitted from forest ecosystems contribute to the formation of secondary organic aerosols (SOAs) and photochemical oxidants (Ox) and affect an ecosystem’s carbon budget. Initial oxidation products of isoprene, methacrolein (MACR) and methyl vinyl ketone (MVK), are key intermediate compounds for the formation of SOAs and Ox, but the production and loss processes of MACR and MVK and its controlling factors within a forest have not been revealed. To address them within a forest and the behavior of related compounds, we measured vertical concentrations and fluxes of monoterpenes, isoprene, and MACR+MVK in a pine-oak forest during summer. Monoterpene concentrations were the highest near the forest floor. A higher isoprene concentration was observed at the height of the Quercus trees. High positive fluxes of monoterpenes and isoprene were observed during the day. The average flux of isoprene during the measurement period was 2.6 times higher than that of monoterpene. Quercus in the lower layer of the forest can be an important source of isoprene, even though the light intensity was estimated much lower than that of red pine canopy. The MACR+MVK concentrations did not show clear vertical gradient patterns. Both positive and negative MACR+MVK fluxes were observed and large positive MACR+MVK fluxes were occasionally observed under a relatively high O3 concentration and isoprene flux around noon or during the afternoon, suggesting that they are produced more frequently by reaction with reactive species including O3 at a higher temperature. Our results demonstrate that, to investigate sink and source dynamics of MACR+MVK above a forest, it is necessary to separately estimate production rate of MACR+MVK, which depends on isoprene emission from the target and surrounding forests, O3 concentration, temperature, and its deposition rate, which is controlled by its concentration and micrometeorological factors.
The irradiance of solar radiation in a greenhouse with a complex structure was calculated using a diagram for sky view factor (DSVF) and compared with observed values. Structural materials (such as side pillars and rafters) and non-structural materials (such as lock channels, door frames, and ventilation fans) were treated as sunshine obstacles, including lower rafters and equal leg angles in the inner spaces of the greenhouse. Radiation directions simulated using a DSVF were used for calculating the irradiance of diffuse solar radiation. With respect to the irradiance of total solar radiation on a sunny day, the calculated values were found to be higher than the observed values early in the morning. However, the overall fluctuation due to diurnal change of the solar elevation and in the sharp drops due to the sunshine obstacles were reproduced. Furthermore, the diurnal changes of the irradiance of non-direct solar radiation on a sunny day and the irradiance of total and non-direct solar radiations on a cloudy day could also be reproduced. The relative error of the calculated irradiance of daytime (from 04:00 to 20:00) total and non-direct solar radiations to the measured value was 4.3% for the total radiation on the sunny day, 5.5% for the non-direct radiation on the sunny day, −1.1% for the total radiation on the cloudy day, and 0.3% for the non-direct radiation on the cloudy day. The results of this study indicated that the DSVF can be useful for calculating diffuse solar radiation.
Phenology is the study of periodic biologic changes that plants are going through, under the influence of environmental factors, especially temperature. The present paper evaluates the behaviour of Prunus spinosa L. genotypes under the fluctuations of climatic factors by calculating the average time elapsed from bud-breaking to blooming, the average time elapsed between different phenophases, the heat demand and the chilling requirement. The data obtained show that the onset of spring season phenological phases is significantly speeded-up by temperatures increase and provides useful information on temperature influence on phenologic phased triggering and better understanding of temperature influence on phenology in Prunus spinosa L. genotypes in Oltenia region of Romania.