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Phyllostachys edulis is a spectacularly fast-growing species that completes its height growth within 2 months after the shoot emerges without producing leaves (fast-growing period, FGP). This phase was considered heterotrophic, with the carbon necessary for the growth being transferred from the mature culms via the rhizomes, although previous studies observed key enzymes and anatomical features related to C4-carbon fixation in developing culms. We tested whether C4-photosynthesis or dark-CO2 fixation through anaplerotic reactions significantly contributes to the FGP, resulting in differences in the natural abundance of δ 13C in bulk organic matter and organic compounds. Further, pulse-13CO2-labelling was performed on developing culms, either from the surface or from the internal hollow, to ascertain whether significant CO2 fixation occurs in developing culms. δ 13C of young shoots and developing culms were higher (−26.3 to −26.9 ‰) compared to all organs of mature bamboos (−28.4 to −30.1 ‰). Developing culms contained chlorophylls, most observed in the skin tissues. After pulse-13CO2-labelling, the polar fraction extracted from the skin tissues was slightly enriched in 13C, and only a weak 13C enrichment was observed in inner tissues. Main carbon source sustaining the FGP was not assimilated by the developing culm, while a limited anaplerotic fixation of respired CO2 cannot be excluded and is more likely than C4-photosynthetic carbon fixation. [ABSTRACT FROM AUTHOR]

The photochemical reflectance index (PRI) and the chlorophyll carotenoid index (CCI) are carotenoid-sensitive vegetation indices, which can monitor vegetation's photosynthetic activities. One unique satellite named "Global Change Observation Mission-Climate (GCOM-C)" is equipped with a sensor, "Second Generation Global Imager (SGLI)", which has the potential to frequently and simultaneously observe PRI and CCI over a wide swath. However, the observation accuracy of PRI and CCI derived from GCOM-C/SGLI remains unclear in forests. Thus, we demonstrated their accuracy assessment by comparing them with in situ data. We collected in situ spectral irradiance data at four forest sites in Japan for three years. We statistically compared satellite PRI with in situ PRI, and satellite CCI with in situ CCI. From the obtained results, the satellite PRI showed poor agreement (the best: r = 0.294 ( p < 0.05 )) and the satellite CCI showed good agreement (the best: r = 0.911 ( p < 0.001 )). The greater agreement of satellite CCI is possibly because satellite CCI contained fewer outliers and satellite CCI was more resistant to small noise, compared to satellite PRI. Our results suggest that the satellite CCI is more suitable for practical use than the satellite PRI with the latest version (version 3) of GCOM-C/SGLI's products. [ABSTRACT FROM AUTHOR]

Tree species that close stomata early in response to drought are likely to suffer from an imbalance between limited carbohydrate supply due to reduced photosynthesis and metabolic demand. Our objective was to clarify the dynamic responses of non-structural carbohydrates to drought in a water-saving species, the hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.). To this end, we pulse-labeled young trees with 13CO2 10 days after the beginning of the drought treatment. Trees were harvested 7 days later, early during drought progression, and 86 days later when they had suffered from a long and severe drought. The labeled carbon (C) was traced in phloem extract, in the organic matter and starch of all the organs, and in the soluble sugars (sucrose, glucose and fructose) of the most metabolically active organs (foliage, green branches and fine roots). No drought-related changes in labeled C partitioning between belowground and aboveground organs were observed. The C allocation between non-structural carbohydrates was altered early during drought progression: starch concentration was lower by half in the photosynthetic organs, while the concentration of almost all soluble sugars tended to increase. The preferential allocation of labeled C to glucose and fructose reflected an increased demand for soluble sugars for osmotic adjustment. After 3 months of a lethal drought, the concentrations of soluble sugars and starch were admittedly lower in drought-stressed trees than in the controls, but the pool of non-structural carbohydrates was far from completely depleted. However, the allocation to storage had been impaired by drought; photosynthesis and the sugar translocation rate had also been reduced by drought. Failure to maintain cell turgor through osmoregulation and to refill embolized xylem due to the depletion in soluble sugars in the roots could have resulted in tree mortality in hinoki cypress, though the total pool of carbohydrate was not completely depleted. [ABSTRACT FROM AUTHOR]

Isotope ratios of carbon dioxide and water vapour in the near-surface air were continuously measured for one month in an urban area of the city of Nagoya in central Japan in September 2010 using laser spectroscopic techniques. During the passages of a typhoon and a stationary front in the observation period, remarkable changes in the isotope ratios of CO2and water vapour were observed. The isotope ratios of both CO2and water vapour decreased during the typhoon passage. The decreases can be attributed to the air coming from an industrial area and the rainout effects of the typhoon, respectively. During the passage of the stationary front, δ13C–CO2and δ18O–CO2increased, while δ2H–H2Ov and δ18O–H2Ov decreased. These changes can be attributed to the air coming from rural areas and the air surrounding the observational site changing from a subtropical air mass to a subpolar air mass during the passage of the stationary front. A clear relationship was observed between the isotopic CO2and water vapour and the meteorological phenomena. Therefore, isotopic information of CO2and H2Ov could be used as a tracer of meteorological information. [ABSTRACT FROM PUBLISHER]

To evaluate water use and the supporting water source of a tropical rainforest, a 4-year assessment of evapotranspiration (ET) was conducted in Pasoh Forest Reserve, a lowland dipterocarp forest in Peninsular Malaysia. The eddy covariance method and isotope signals of rain, plant, soil, and stream waters were used to determine forest water sources under different moisture conditions. Four sampling events were conducted to collect soil and plant twig samples in wet, moderate, dry, and very dry conditions for the identification of isotopic signals. Annual ET from 2012 to 2015 was quite stable with an average of 1,182 ± 26 mm, and a substantial daily ET was observed even during drought periods, although some decline was observed, corresponding with volumetric soil water content. During the wet period, water for ET was supplied from the surface soil layer between 0 and 0.5 m, whereas in the dry period, approximately 50% to 90% was supplied from the deeper soil layer below 0.5-m depth, originating from water precipitated several months previously at this forest. Isotope signatures demonstrated that the water sources of the plants, soil, and stream were all different. Water in plants was often different from soil water, probably because plant water came from a different source than water that was strongly bound to the soil particles. Plants showed no preference for soil depth with their size, whereas the existence of storage water in the xylem was suggested. The evapotranspiration at this forest is balanced and maintained using most of the available water sources except for a proportion of rapid response run-off. [ABSTRACT FROM AUTHOR]

This study was undertaken to evaluate the effects of climatic variability on inter-annual variations in each component of evapotranspiration ( ET) and the total ET in a temperate coniferous forest in Japan. We conducted eddy covariance flux and meteorological measurements for 7 years and parameterized a one-dimensional multi-layer biosphere-atmosphere model (Kosugi et al., ) that partitions ET to transpiration ( Tr), wet-canopy evaporation ( Ewet), and soil evaporation ( Esoil). The model was validated with the observed flux data. Using the model, the components of ET were estimated for the 7 years. Annual precipitation, ET, Tr, Ewet, and Esoil over the 7 years were 1536 ± 334 mm, 752 ± 29 mm, 425 ± 37 mm, 219 ± 34 mm, and 108 ± 10 mm, respectively. The maximum inter-annual fluctuation of observed ET was 64 mm with a coefficient of variance (CV) of 2.7%, in contrast to relatively large year-to-year variations in annual rainfall (CV = 20.1%). Tr was related to the vapour pressure deficit, incoming radiation, and air temperature with relatively small inter-annual variations (CV = 8.2%). Esoil (CV = 8.6%) was related mainly to the vapour pressure deficit. Ewet was related to precipitation with large inter-annual variations (CV = 14.3%) because of the variability in precipitation. The variations in Ewet were counterbalanced by the variations in Tr and Esoil, producing the small inter-annual variations in total ET. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We conducted continuous, high time-resolution measurements of CO2and water vapour isotopologues (16O12C16O,16O13C16O and18O12C16O for CO2, and H218O for water vapour) in a red pine forest at the foot of Mt. Fuji for 9 days from the end of July 2010 usingin situabsorption laser spectroscopy. The δ18O values in water vapour were estimated using the δ2H–δ18O relationship. At a scale of several days, the temporal variations in δ18O-CO2and δ18O-H2O are similar. The orders of the daily Keeling plots are almost identical. A possible reason for the similar behaviour of δ18O-CO2and δ18O-H2O is considered to be that the air masses with different water vapour isotopic ratios moved into the forest, and changed the atmosphere of the forest. A significant correlation was observed between δ18O-CO2and δ13C-CO2values at nighttime (r2≈0.9) due to mixing between soil (and/or leaf) respiration and tropospheric CO2. The ratios of the discrimination coefficients (Δa/Δ) for oxygen (Δa) and carbon (Δ) isotopes during photosynthesis were estimated in the range of 0.7–1.2 from the daytime correlations between δ18O-CO2and δ13C-CO2values. [ABSTRACT FROM PUBLISHER]

The article presents a study on the fluxes of sensible and latent heat in Pasoh Forest Reserve low-land diptecrocarp forest in Peninsular Malaysia. The study conducted observations in the said forest reserve with various considerations including canopy height, plant area index, and altitude of core area. Results show that sensible heat flux fluctuates depending on the fluctuation of radiation in wet and dry season. It adds that excess water loss was due to decreased midday surface conductance.

Ambient CO2 concentration, air temperature and relative humidity were measured intermittently for a 3-year period from the floor to the canopy top of a tropical rainforest in Pasoh, Peninsular Malaysia. Mean diurnal CO2 storage flux ( Sc; μmol m−2 s−1) and sensible and latent heat storage fluxes ( Qa and Qw; W m−2) ranged from −12.7 to 3.2 μmol m−2 s−1, −15 to 27 W m−2 and −10 to 20 W m−2, respectively. Small differences in diurnal changes were observed in Sc and Qa between the driest and wettest periods. Compared with the ranges of mean diurnal CO2 eddy flux (−14.7 to 4.9 μmol m−2 s−1), sensible eddy flux (−12 to 169 W m−2) and latent eddy flux (0 to 250 W m−2), the contribution of CO2 storage flux was especially large. Comparison with summertime data from a temperate Japanese cypress forest suggested a higher contribution of Sc in the tropical rainforest, probably mainly due to the difference in nighttime friction velocity at the sites. On the other hand, differences in Qa and Qw were smaller than the difference in Sc, probably because of the smaller nighttime sinks/sources of heat and water vapour. [ABSTRACT FROM AUTHOR]

Abstract: The eddy covariance method was used to observe carbon dioxide flux (F c) for 3 years over an old-growth tropical rainforest at Pasoh in Peninsular Malaysia. The average nighttime F c and NEE were 3.6 and 4.7μmolm−2 s−1, respectively, when friction velocity (u * )≥0.2, while the average soil respiration rate measured occasionally with the chamber method was estimated to be 4.1μmolm−2 s−1 if we used the relationship between volumetric soil water content, or 3.8μmolm−2 s−1 if we used the pure average of nine observations. The comparison of F c, NEE and soil respiration strongly suggests that nighttime CO2 efflux was underestimated even when the CO2 storage term is considered. The correction of F c data for low u * did not correct this underestimate, and it was strongly suggested that this forest was not a strong carbon sink, as raw F c data, even with the u * filtering, implied. Monthly average daytime diurnal changes in CO2 exchange over the canopy were fairly constant from 2003 to 2005 despite fluctuations in soil moisture, solar radiation, air temperature and vapor pressure deficit between dry and wet periods. An obvious inhibition of canopy CO2 exchange in the afternoon coupling with increases in VPD and air temperature was observed year-round. In the case of nighttime NEE, a slight increase in wet period was observed. Diurnal pattern of CO2 exchange revealed that obvious restriction of canopy photosynthesis in the afternoon was occurred in this forest irrespective of soil moisture. Seasonal and annual patterns of CO2 exchange reveal that one of the main causes which induce the difference in NEE pattern between Amazonian and Southeast Asian rainforests was not the difference in daytime photosynthesis but the difference in ecosystem respiration related with dry and rainy seasons. The decrease of CO2 uptake (increase of NEE) at wet period was also observed at this site, but did not form an obvious seasonality such as in Amazonian forests. [Copyright &y& Elsevier]

Effects of heterogeneity in stomatal behavior on gas-exchange characteristics of leaves from four tree species growing in different climates, including temperate, tropical monsoon and tropical rain forest, were investigated by combining gas-exchange measurements and the pressure-infiltration method. Field observations indicated linear relationships between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area (open stomata area) in Dipterocarpus sublamellatus Foxw. and Neobalanocarpus heimii (King) Ashton in a tropical rain forest in Peninsular Malaysia, whereas the ratio of infiltrated to non-infiltrated area rapidly increased up to the whole-leaf conductance at which the entire leaf was infiltrated in Cinnamomum camphora Sieb. in a temperate evergreen forest in Japan and in Azadirachta indica Juss. in a tropical monsoon area in Thailand. These results strongly suggest small ranges in bell-shaped stomatal conductance distributions in C. camphora and A. indica and bimodal stomatal conductance distributions in D. sublamellatus and N. heimii. The values of normalized maximum carboxylation rate at 25 °C (Vcmax25) derived from gas-exchange measurements were not constant, but decreased with decreasing whole-leaf conductance in D. sublamellatus and N. heimii. A gas-exchange model analysis revealed a linear relationship between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area for bimodal stomatal conductance distributions, whereas for bell-shaped distributions, the relationships were nonlinear. Midday depression of apparent Vcmax25 in these species was mainly caused by bimodal stomatal closure. The bimodal stomatal distribution model could also explain diurnal changes in photosynthetic assimilation and transpiration rates in these species. [ABSTRACT FROM PUBLISHER]

Abstract: The spatial distribution of throughfall in a tropical rainforest in Peninsular Malaysia was evaluated using 100 bucket raingauges placed along a line as well as two large raingauges (collection areas of 9.58 and 7.08m2). Throughfall was clearly large in a treefall gap although it was not significantly different between a typical old-growth area with big trees and another area without big trees. A cyclic variation, the scale of which was 10–15m, was detected in the entire forest through Fourier analysis, and this scale roughly corresponded to the index of canopy cover openness. The observations gave the spatial mean value of throughfall with enough accuracy considering that the distribution of throughfall in the forest was controlled by different scale effects consisting of the size of disturbance areas such as gaps as well as the size of individual canopies. [Copyright &y& Elsevier]

To examine the characteristics of carbon exchange in coniferous forests, we analysed the seasonal and diurnal patterns of CO2 exchange, as measured using the eddy covariance method, in a Japanese cypress forest in the Kiryu Experimental Watershed (KEW) in central Japan. The net CO2 exchange data during periods of low-friction velocity conditions and during periods of missing data were interpolated. The daily CO2 uptake was observed throughout the year, with maximum values occurring in early summer. Periods of low carbon uptake were seen in late summer owing to high respiratory CO2 efflux. The diurnal and seasonal patterns of daytime CO2 exchange at KEW were compared with those in a cool-temperate deciduous forest of the Tomakomai Experimental Forest (TOEF) in Japan. The environmental differences between evergreen and deciduous forests affected the seasonal patterns of carbon uptake. Although there were great differences in the mean monthly air temperatures between the sites, the mean monthly daytime carbon uptake was almost equal at both sites during the peak growing period. The carbon-uptake values at the same PAR level were greater before noon than after noon, especially at TOEF, suggesting the stomatal regulation of carbon uptake. [ABSTRACT FROM AUTHOR]

Since biogenic volatile organic compounds (BVOCs) are important precursors of ozone, the monitoring of the BVOC concentration distributions is needed. In general, forest BVOC concentrations increase in summer as well as in other seasons. This study aims to detect temporally sporadic increases in BVOC concentrations in the non-summer months and to analyze the occurring climatic conditions. Using a uniform sampling system and shared gas chromatography–mass spectrometry, the concentrations of isoprene and monoterpenes in six Japanese forests were observed approximately once a month for 3 years. Using the observed data, the relations between the BVOC concentration increases and meteorological factors were evaluated. Twenty instances of temporal increases in BVOC concentrations were observed. These mainly occurred in spring for isoprene and in autumn for monoterpenes. Most of the increases in the non-summer months were observed after a rainfall event, when the daily temperature range was large, suggesting that wind, rain, and a rapid diurnal temperature rise could be factors in the non-summer months. Thus, the network monitoring of BVOC concentrations might be effective for understanding the effects of factors other than temperature, and the mechanisms and frequency of the temporal increases, on the BVOC concentrations in various forests. [ABSTRACT FROM AUTHOR]

Highlights • We developed a model based on the mechanisms of photosynthesis and growth/decline in C 3 turfgrass. • We also developed an algorithm for mapping the growth conditions of turfgrass on a football field. • Model can be used to develop management plans and facilitate the design of stadiums for turfgrass. • Model has a possibility to aid the assessment and management of a wider range of agricultural fields. Abstract We developed a predictive model based on the mechanisms of photosynthesis and growth/decline in C 3 turfgrass, which has applications for turfgrass management plans over a wide range of environments, including shaded growth conditions, such as turfed football stadiums. The numerical formulas, algorithms, and parameters for defining photosynthesis and the growth/decline in a turfgrass community are presented. The parameters that were optimized to simulate photosynthesis and growth/decline were included in the multilayer model for gas exchange and the vegetation growth/decline model. The model was validated using data collected on leaf biomass, root biomass, leaf area index, cumulative mowing, cumulative root growth, and litter (leaf and root) over a 2-year period in a stadium in which Japanese Professional Football League games are played. We also developed an algorithm to simulate and map the growth conditions in two dimensions. To fit the simulated and observed data better, we varied the parameters by season and irradiance conditions. The results showed that changes in leaf and root biomass over intervals that were less than annual affected gas exchange and the balance between respiration and assimilation rates and, in turn, caused changes in leaf and root biomass. [ABSTRACT FROM AUTHOR]

Abstract: Underestimation of nocturnal CO2 respiration using the eddy covariance method under calm conditions remains an unsolved problem at many flux observation sites in forests. To evaluate nocturnal CO2 exchange in a Japanese cypress forest, we observed CO2 flux above the canopy (F c), changes in CO2 storage in the canopy (S t) and soil, and trunk and foliar respiration for 2 years (2003–2004). We scaled these chamber data to the soil, trunk, and foliar respiration per unit of ground area (F s, F t, F f, respectively) and used the relationships of F s, F t, and F f with air or soil temperature for comparison with canopy-scale CO2 exchange measurements (=F c + S t). The annual average F s, F t, and F f were 714gCm−2 year−1, 170gCm−2 year−1, and 575gCm−2 year−1, respectively. At small friction velocity (u *), nocturnal F c + S t was smaller than F s + F t + F f estimated using the chamber method, whereas the two values were almost the same at large u *. We replaced F c + S t measured during calm nocturnal periods with a value simulated using a temperature response function derived during well-mixed nocturnal periods. With this correction, the estimated net ecosystem exchange (NEE) from F c + S t data ranged from −713gCm−2 year−1 to −412gCm−2 year−1 in 2003 and from −883gCm−2 year−1 to −603gCm−2 year−1 in 2004, depending on the u * threshold. When we replaced all nocturnal F c + S t data with F s + F t + F f estimated using the chamber method, NEE was −506gCm−2 year−1 and −682gCm−2 year−1 for 2003 and 2004, respectively. [Copyright &y& Elsevier]

We conducted a 13 CO 2 pulse-labeling experiment to trace the transfer of recently assimilated carbon (C) from woody plants to soil microarthropods. We investigated the utilization of root-derived C for six species of Collembola that differ in terms of their morphological traits and vertical distributions. Although species living in deeper soil layers, such as humus and mineral soil, have traditionally been considered to have close relationships with plant roots, we showed that even species that inhabit the litter layer utilized root-derived C. Additionally, we found interspecific differences in root-derived C utilization among species living in the same soil layer. This result suggests that collembolan species exhibiting the same vertical distribution have species-specific functional roles in soil processes, which contrasts with the previously accepted view that they are relatively redundant in terms of their belowground functions related to their dietary traits. [ABSTRACT FROM AUTHOR]