Naomi Kodama

Direct measurements of ecophysiological processes such as leaf photosynthesis are often hampered due to the excessive time required for gas-exchange measurements and the limited availability of multiple gas analyzers. Although recent advancements in commercially available instruments have improved the ability to take measurements more conveniently,...

Earthworms are critical soil organisms, facilitating biogeochemical cycles in soil ecosystems through the formation of soil aggregates by drilling soil and accelerating microbial activity. However, the dynamic measurements of earthworm respiration have not been updated for several decades, although understanding earthworm respiration is a fundament...

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...

Pinus thunbergii trees growing on Pacific coastal sand dunes in Japan were immersed by the tsunami that followed the Great East Japan Earthquake on 11 March 2011. Even trees that survived direct physical damage began to die during the following summer, probably because of the physiological stress of salt water immersion. The objectives of this stud...

We conducted continuous, high time-resolution measurements of CO2 and water vapour isotopologues ((16)O(12)C(16)O, (16)O(13)C(16)O and (18)O(12)C(16)O for CO2, and H2(18)O for water vapour) in a red pine forest at the foot of Mt. Fuji for 9 days from the end of July 2010 using in situ absorption laser spectroscopy. The δ(18)O values in water vapour...

Harpin proteins produced by plant-pathogenic Gram-negative bacteria are the venerable player in regulating bacterial virulence and inducing plant growth and defenses. A major gap in these effects is plant sensing linked to cellular responses, and plant sensor for harpin Hpa1 from rice bacterial blight pathogen points to plasma membrane intrinsic pr...

We investigated stomatal conductance (g s) and mesophyll conductance (g m) in response to atmospheric CO2 concentration [CO2] in two primitive land plants, the fern species Pteridium aquilinum and Thelypteris dentata, using the concurrent measurement of leaf gas exchange and carbon isotope discrimination. [CO2] was initially decreased from 400 to 2...

Earthworms are important soil macrofauna inhabiting almost all ecosystems. Their biomass is large and their burrowing and ingestion of soils alters soil physicochemical properties. Because of their large biomass, earthworms are regarded as an indicator of "soil heath". However, primarily because the difficulties in quantifying their behavior, the e...

Understanding environmental and physiological controls of the variations in δ13C of CO2 respired (δ13CR) from different compartments of an ecosystem is important for separation of CO2 fluxes and to assess coupling between assimilation and respiration. In a wheat field, over 3 days we characterised the temporal dynamics of δ13CR from shoots and root...

Mesophyll diffusion conductance to CO(2) is a key photosynthetic trait that has been studied intensively in the past years. The intention of the present review is to update knowledge of g(m), and highlight the important unknown and controversial aspects that require future work. The photosynthetic limitation imposed by mesophyll conductance is larg...

Leaf water gets isotopically enriched through transpiration, and diffusion of enriched water through the leaf depends on transpiration flow and the effective path length (L). The aim of this work was to relate L with physiological variables likely to respond to similar processes. We studied the response to drought and vein severing of leaf lamina h...

At present, there is lack of knowledge on how plant physiological processes, the transfer of carbon within the plant, carbon storage and remobilization in the plant tissues as well as the release of carbon from the roots to the soil interact with ecosystem-scale processes. On the background of global climate change, we need to mechanistically link...

The diffusion of CO2 within leaves during photosynthesis can be an important limiting factor for productivity. Mesophyll conductance had been thought to be infinite or constant over the time. Recent studies, however, have revealed that mesophyll conductance is altered by growth environment,and may respond rapidly to some environmental variables suc...

Carbon and oxygen isotope discrimination of CO2 during photosynthesis (Δ13Cobs and Δ18Oobs) were measured along a monocot leaf, triticale (Triticum × Secale). Both Δ13Cobs and Δ18Oobs increased towards the leaf tip. While this was expected for Δ18Oobs, because of progressive enrichment of leaf water associated with the Péclet effect, the result was...

The CO₂ respired by darkened, light-adapted, leaves is enriched in ¹³C during the first minutes, and this effect may be related to rapid changes in leaf respiratory biochemistry upon darkening. We hypothesized that this effect would be evident at the ecosystem scale. High temporal resolution measurements of the carbon isotope composition of ecosyst...

Leaf water gets isotopically enriched through transpiration, and diffusion of enriched water through the leaf depends on transpiration flow and the effective path length (L). The aim of this work was to relate L with physiological variables likely to respond to similar processes. We studied the response to drought and vein severing of leaf lamina h...

Understanding environmental and physiological controls of the variations in +¦ 13C of CO 2 respired (+¦ 13C R) from different compartments of an ecosystem is important for separation of CO 2 fluxes and to assess coupling between assimilation and respiration. In a wheat field, over 3 days we characterised the temporal dynamics of +¦ 13C R from shoot...

Carbon and oxygen isotope discrimination of CO2 during photosynthesis (Δ13C obs and Δ18O obs) were measured along a monocot leaf, triticale (Triticum × Secale). Both Δ13C obs and Δ18O obs increased towards the leaf tip. While this was expected for Δ18O obs, because of progressive enrichment of leaf water associated with the Péclet effect, the resul...

Starch and soluble sugars are the major photosynthetic products, and their carbon isotope signatures reflect external versus internal limitations of CO(2) fixation. There has been recent renewed interest in the isotope composition of carbohydrates, mainly for use in CO(2) flux partitioning studies at the ecosystem level. The major obstacle to the u...

The (13)C isotopic signature (C stable isotope ratio; delta(13)C) of CO(2) respired from forest ecosystems and their particular compartments are known to be influenced by temporal changes in environmental conditions affecting C isotope fractionation during photosynthesis. Whereas most studies have assessed temporal variation in delta(13)C of ecosys...

Post-photosynthetic carbon isotope fractionation might alter the isotopic signal imprinted on organic matter (OM) during primary carbon fixation by Rubisco. To characterise the influence of post-photosynthetic processes, we investigated the effect of starch storage and remobilisation on the stable carbon isotope signature (delta C-13) of different...

Understanding ecosystem water fluxes has gained increasing attention, as climate scenarios predict a drier environment for many parts of the world. Evaporative enrichment of (18)O (Delta(18)O) of leaf water and subsequent enrichment of plant organic matter can be used to characterize environmental and physiological factors that control evaporation,...

We aimed to quantify the separate effects of photosynthetic and postphotosynthetic carbon isotope discrimination on δ13C of the fast-turn-over carbon pool (water soluble organic carbon and CO2 emitted from heterotrophic tissues), including their diel variation, along the pathway of carbon transport from the foliage to the base of the stem. For that...

Following results of regional climatic mode ls, the regional impact of climate change in the southern Rhine valley in Central Europe will result in hotter and dryer summer seasons. Because this region is already the warmest and dryest area in Germany, it seems to be favourite to perform interdisciplinary research on climate change impacts. Whic...