All issues
Volume 67, Issue 1
Displaying 1-5 of 5 articles from this issue
- |<
- <
- 1
- >
- >|
Full Papers
-
Takashi MATSUBARA, Yoshiko KOSUGI, Satoru TAKANASHI, Yoko MIZOTA, Masa ...2011 Volume 67 Issue 1 Pages 1-12
Published: March 10, 2011
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSSeasonal variation in non-assimilatory organ and leaf biomass and necromass, leaf area index (LAI), leaf mass per unit area (LMA), and leaf nitrogen content per unit leaf area of managed C3 cool-season turfgrass (Kentucky bluegrass, Poa pratensis L.) fields under four light conditions (irradiance levels: 100, 62, 48, 20%) were examined in situ over 2 years. Seasonal fluctuations in light and the temperature dependence of the gas exchange of intact leaves grown under three light conditions (irradiance levels: 100, 48, 20%) were also examined for 1 year. The magnitude of spring growth and summer decline in non-assimilatory organ and leaf biomass depended on the light conditions. Both non-assimilatory organ and leaf biomass were higher in the sunnier plots, as was the ratio of non-assimilatory organs to whole biomass. A step wise acclimatization to low irradiance reduced the allocation to non-assimilatory organs to maintain leaf biomass, limited LMA to maintain the LAI, and limited the latter to retain leaf nitrogen per unit leaf area, depending on the shade level. Kentucky bluegrass growing under lower light conditions had similar single-leaf photosynthetic abilities until early summer, but the normalized maximum carboxylation rate at 25°C [Vcmax25] decreased during the decline of turfgrass in summer, depending on the shade level, which corresponded to the decline in leaf nitrogen content per unit leaf area.View full abstractDownload PDF (2444K) -
Yasuhiro KOMINAMI2011 Volume 67 Issue 1 Pages 13-20
Published: March 10, 2011
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSThe quantity of CO2 carried away by snowmelt during the thawing of a deposited snow layer was measured in an area subject to seasonal accumulation of snow. The concentration of dissolved CO2 was measured in snowmelt discharged from the outlet of a paddy field with heavy clay soil in Joetsu City, Niigata Prefecture, Japan. Samples were taken every few hours over a period of three days. The CO2 flux Fwater transported by the snowmelt was estimated from changes in the concentration of dissolved CO2, with the CO2 concentration continuously measured at the bottom of the deposited snow layer, and the quantity of snowmelt estimated from heat balance measurements. The ratio of the CO2 concentration, Csnow, to that dissolved in the snowmelt, Cwater, gradually decreased as the quantity of snow melted per unit time increased. Therefore, assuming this ratio to be proportional to the inverse of the snowmelt flow speed, a regression was carried out, based on the fact the flow speed is proportional to the quantity of melted snow per unit time raised to a power of 2/3. To assess the validity of the estimated Fwater, we studied the balance of CO2 in the deposited snow layer by using the CO2 store in the deposited snow. The quantity value of the soil respiration flux estimated from the balance of CO2 in the deposited snow layer was close to the average soil respiration flux during the snow-covered period estimated by the CO2 concentration gradient and the volume fraction of air in the snow layer previously deposited in the same paddy field.View full abstractDownload PDF (850K) -
Hiroki OUE, Kazuhiko KOBAYASHI, Jianguo ZHU, Wenshan GUO, Xinkai ZHU2011 Volume 67 Issue 1 Pages 21-32
Published: March 10, 2011
Released on J-STAGE: April 04, 2011
Advance online publication: January 14, 2011JOURNAL FREE ACCESSTo predict the yield losses in winter wheat due to the elevated ozone concentration in eastern China, we tested the ozone dose response functions (O3DRF), i.e. the relationship between the accumulated stomatal ozone flux above a threshold of 6 nmol m-2 s-1 (AFst6) and the relative grain yield (RY), via observations of three cultivars of winter wheat in a FACE-Ozone (free-air concentration enrichment with ozone) experiment. We also presented a new O3DRF based on the new ozone dose using the FACE-Ozone results.
The AFst6 was calculated by applying the flag leaf stomatal conductance model of each cultivar developed in this study. The observed RY fell below the linear O3DRF: ‘RY (%)=100-4.8 AFst6’, which has been derived in Europe and widely used (Pleijel et al., 2000; 2007), at higher AFst6. This deviation was due to the synergetic effect of the accelerated drop in photosynthesis and the decelerated increase of AFst6 caused by the stomatal closure at a higher ozone dose. We therefore presented a curvilinear O3DRF: ‘RY (%)=100-k (AFst6)l’ for the wheat cultivars in the FACE-Ozone experiment.
We also explored the applicability of the relative net primary productivity (NPP) of the flag leaf canopy (RNPPc) as a better ozone dose than AFst6. The NPP of the flag leaf was calculated by applying the flag leaf photosynthesis model developed in this study for each cultivar. The relationship between RNPPc and RY of the three cultivars showed good correlation, suggesting that RNPPc could be used as O3DRF to predict RY or the yield loss due to the increased ozone concentration.View full abstractDownload PDF (1252K) -
Daiyu ITO, Sachinobu ISHIDA, Dai MATSUSHIMA2011 Volume 67 Issue 1 Pages 33-42
Published: March 10, 2011
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSTo precisely evaluate the impact of canopy heat storage on the energy balance of an apple orchard, heat storage flux and its diurnal changes were examined by observation during both growing and sprouting periods. The majority of canopy heat storage was trunk heat storage, followed by sensible and latent heat storages, while the leaf heat storage was negligible. The canopy heat storage flux peaked between 0700 and 0930 and bottomed out at around 1800. The range of diurnal flux was larger in the sprouting period than in the growing period, and likewise on days of higher solar radiation. It reached 66 Wm-2 on fine days in the sprouting period. By taking HS into account, the energy closure ratio for the eddy covariance method increased by 1.03 and 1.16 times in daytime and nighttime, respectively, and this increase was generally thought to improve the energy imbalance. The canopy heat storage flux could be well estimated from the difference of air temperature above the canopy at present and an hour before (RMSE 7 Wm-2).View full abstractDownload PDF (1203K)
Short Papers
-
Takafumi MIYAMA, Kenichi YOSHIMURA, Yuji KOMINAMI, Motonori OKUMURA, M ...2011 Volume 67 Issue 1 Pages 43-51
Published: March 10, 2011
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSBecause methanogens have a relatively short retention time in flowing water, mountain streams are generally considered unsuitable for their growth. However, litter-covered stream edges and sandbars of mountain streams are potential CH4 emission areas because methanogens can persist at such sites. In the present study, we focused on these possible CH4 sources. To evaluate spatial variations in CH4 emissions from sites near a mountain stream, we installed 46 chambers on the stream bed and its edge. We observed high CH4 emission rates from the sandbars in the stream and from the stream edge when they were covered with leaf litter. In contrast, from chambers located upslope away from the stream or below the water level in the stream, we observed almost no CH4 emissions. To evaluate the effect of litter covering the soil, we experimentally put 20 g or 40 g (dry weight) of leaves, woody tissue, or acorns from Quercus serrata Murray into closed chambers and observed the CH4 flux weekly between 2 April and 22 October 2009. We observed the highest CH4 emission rates in chambers with 40 g of leaf litter; in these chambers, the oxidation-reduction potential (ORP) was negatively correlated with the CH4 emission rate. These results suggest that CH4 can be emitted from sandbars and edges of mountain streams, with larger emissions occurring when surfaces are covered with leaf litter and when ORP is low and the soil temperature high. To evaluate the overall role of the forest in CH4 circulation, further studies of CH4 emissions from mountain stream sites covered with leaf litter are needed.View full abstractDownload PDF (939K)
- |<
- <
- 1
- >
- >|