• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.346-358
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• 2023

Due to the acceleration of climate change or global warming, it is important to predict rice productivity in the future and investigate physiological changes in rice plants. The research aimed to explore how rice adapts to climate change by examining the response of nitrogen absorption and nitrogen use efficiency in rice under elevated levels of carbon dioxide and temperature, utilizing the SPAR system for analysis. The temperature increased by +4.7 ℃ in comparison to the period from 2001 to 2010, while the carbon dioxide concentration was held steady at 800 ppm, aligning with South Korea's late 21st-century RCP8.5 scenario. Nitrogen was applied as fertilizer at rates of 0, 9, and 18 kg 10a^-1, respectively. Under conditions of climate change, there was an 81% increase in the number of panicles compared to the present situation. However, grain weight decreased by 38% as a result of reduction in the grain filling rate. BNUE, indicative of the nitrogen use efficiency in plant biomass, exhibited a high value under climate change conditions. However, both NUEg and ANUE, associated with grain production, experienced a notable and significant decrease. In comparison to the current conditions, nitrogen uptake in leaves and stems increased by 100% and 151%, respectively. However, there was a 25% decrease in nitrogen uptake in the panicle. Likewise, the nitrogen content and NDFF (Nitrogen Derived from Fertilizer) in the sink organs, namely leaves and roots, were elevated in comparison to current levels. Therefore, it is imperative to ensure resources by mitigating the decrease in ripening rates under climate change conditions. Moreover, there seems to be a requirement for follow-up research to enhance the flow of photosynthetic products under climate change conditions.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.2
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• pp.173-181
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• 2015

Fluxes of carbon dioxide ($CO_2$) were measured above crop canopy using the Eddy Covariance (EC) method, and emission rate of methane ($CH_4$) was measured using Automatic Open/Close Chamber (AOCC) method during the 2012-2013 barley and rice growing season in a barley-rice double cropping field of Gimje, Korea. The net ecosystem exchange (NEE) of $CO_2$ in the paddy field was analyzed to be affected by crop growth (biomass, LAI, etc.) and environment (air temperature, solar radiation, etc.) factors. On the other hand, the emission rate of $CH_4$ was estimated to be affected by water management (soil condition). NEE of $CO_2$ in barley, rice and fallow period was -100.2, -374.1 and $+41.2g\;C\;m^{-2}$, respectively, and $CH_4$ emission in barley and rice period was 0.2 and $17.3g\;C\;m^{-2}$, respectively. When considering only $CO_2$, the barley-rice double cropping ecosystem was estimated as a carbon sink ($-433.0g\;C\;m^{-2}$). However, after considering the harvested crop biomass ($+600.3g\;C\;m^{-2}$) and $CH_4$ emission ($+17.5g\;C\;m^{-2}$), it turned into a carbon source ($+184.7g\;C\;m^{-2}$).

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.235-244
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• 2007

Potentials of AR CDM project in North Korea are assessed and feasible land area for AR CDM project is estimated. According to our estimation, There could be 515,000 hectares of forest lands deforested before 1990 in North Korea and 8,854 hectares at the regional level of Gae-sung City, which are eligible for AR CDM project, based on researches of satellite image analyses conducted from 1980's to 1990's. A baseline scenario assumed 44.73 tones of carbon stored in soil per hectare with no vegetation above ground remained during the project period following the default value of IPCC's Good Practice Guidance for LULUCF considering soil structure, climate and land use of the project area. The scenario also assumes that black rocust (Robinia pseudoacacia) is planted and the CDM project is implemented for 20 years. The costs for producing greenhouse gases CER (certified emission reduction) credits include costs of tree planting and forest management, and costs of project negotiation and transactions for issuing the credits. It is estimated that 376 tones of carbon dioxide per hectare can be accumulated and 503 temporary CER credits per hectare and 265 long-term CER credits per hectare could be produced during the project period. It is estimated to cost US$ 4.04 and US$ 7.67 to provide one unit of temporary credit and long-term credit, respectively. These values can be regarded as the cost of conferring emission commitment of a country or a private entity. However, it is not clear which option is better economically because the replacement periods are different in these two cases.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.135-145
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• 2019

Analysis of a long cycle or a trend of time series data based on a long-term observation would require comparability between data observed in the past and the present. In the present study, we proposed an approach to ensure the compatibility among the instruments used for the long-term observation, which would allow to secure continuity of the data. An open-path gas analyzer (Model LI-7500, LI-COR, Inc., USA) has been used for eddy covariance flux measurement in the Gwangneung deciduous forest for more than 10 years. The open-path gas analyzer was replaced by an enclosed-path gas analyzer (Model EC155, Campbell Scientific, Inc., USA) in July 2015. Before completely replacing the gas analyzer, the carbon dioxide ($CO_2$) and latent heat fluxes were collected using both gas analyzers simultaneously during a five-month period from August to December in 2015. It was found that the $CO_2$ fluxes were not significantly different between the gas analyzers under the condition that the daily mean temperature was higher than $0^{\circ}C$. However, the $CO_2$ flux measured by the open-path gas analyzer was negatively biased (from positive sign, i.e., carbon source, to 0 or negative sign, i.e., carbon neutral or sink) due to the instrument surface heating under the condition that the daily mean temperature was lower than $0^{\circ}C$. Despite applying the frequency response correction associated with tube attenuation of water vapor, the latent heat flux measured by the enclosed-path gas analyzer was on average 9% smaller than that measured by the open-path gas analyzer, which resulted in >20% difference of the sums over the study period. These results indicated that application of the additional air density correction would be needed due to the instrument heat and analysis of the long-term observational flux data would be facilitated by understanding the underestimation tendency of latent heat flux measurements by an enclosed-path gas analyzer.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.2
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• pp.61-69
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• 2003

Surface energy and $CO_2$ fluxes have been measured over a farmland in Haenam, Korea since July 2002. Eddy covariance technique, which is the only direct flux measurement method, was employed to quantitatively understand the interaction between the farmland ecosystem and the atmospheric boundary layer. Maintenance of eddy covariance system was the main concern during the early stage of measurement to minimize gaps and uncertainties in the dataset. Half-hourly averaged $CO_2$ concentration showed distinct diurnal and seasonal variations, which were closely related to changes in net ecosystem exchange (NEE) of $CO_2$. Daytime maximum $CO_2$ uptake was about -1.0 mg $CO_2$ m$^{-2}$ s$^{-1}$ in August whereas nighttime $CO_2$ release was up to 0.3 mg $CO_2$ m$^{-2}$ s$^{-1}$ during the summer. Both daytime $CO_2$ uptake and nighttime release decreased gradually with season. During the winter season, NEE was from near zero to 0.05 mg $CO_2$ m$^{-2}$ s$^{-1}$ . FK site was a moderate sink of atmospheric $CO_2$ until September with daily NEE of 22 g $CO_2$ m$^{-2}$ d$^{-1}$ . In October, it became a weak source of $CO_2$ with an emission rate of 2 g $CO_2$ m$^{-2}$ d$^{-1}$ . Long-term flux measurements will continue at FK site to further investigate inter-annual variability in NEE. to better understand these exchange mechanism and in-depth analysis, process-level field experiments and intensive short-term intercomparisons are also expected to be followed.