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  • 1
    Electronic Resource
    Electronic Resource
    Dynamic changes in hydraulic conductivity in petioles of two savanna tree species: factors and mechanisms contributing to the refilling of embolized vessels (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Diel variation in specific hydraulic conductivity (ks) was recorded in petioles of two savanna tree species, Schefflera macrocarpa and Caryocar brasiliense, from central Brazil. These two species have compound leaves with long petioles (10–30 cm). In both species, petiole ks decreased sharply with increasing transpiration rates and declining leaf water potentials (ψL) during the morning. Petiole ks increased during the afternoon while the plants were still transpiring and the water in the non-embolized vessels was still under tension. Dye experiments confirmed that in both species diel variation in ks was associated with embolism formation and repair. When transpiration was prevented in individual leaves, their petiole ks and water potential remained close to their maximum values during the day. When minimum daily ψL on selected branches was experimentally lowered by 0.2–0.6 MPa, the rate of ks recovery during the afternoon was slower in comparison with control branches. Several field manipulations were performed to identify potential mechanisms involved in the refilling of embolized petiole vessels. Removal of the cortex or longitudinal incisions in the cortex prevented afternoon recovery of ks and refilling of embolized vessels. When distilled water was added to petiole surfaces that had been abraded to partially remove the cuticle, ks increased sharply during the morning and early afternoon. Evidence of starch to sugar conversion in the starch sheath cells surrounding the vascular bundles of the petioles was observed during periods of rapid transpiration when the abundance of starch granules in the starch sheath cells surrounding the vascular bundles decreased. Consistent with this, petiole sugar content was highest in the early afternoon. The most parsimonious explanation of the field observations and the experimental results was that an increase in osmotically active solutes in cells outside the vascular bundles at around midday leads to water uptake by these cells. However, the concurrent increase in tissue volume is partially constrained by the cortex, resulting in a transient pressure imbalance that may drive radial water movement in the direction of the embolized vessels, thereby refilling them and restoring water flow. This study thus presents evidence that embolism formation and repair are two distinct phenomena controlled by different variables. The degree of embolism is a function of tension, and the rate of refilling a function of internal pressure imbalances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0140-7791.2003.01082.x
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  • 2
    Electronic Resource
    Electronic Resource
    Isotopic fractionation during cellulose synthesis in two mangrove species: Salinity effects
    Amsterdam : Elsevier
    Phytochemistry 31 (1992), S. 2623-2626 
    Details
    ISSN: 0031-9422
    Keywords: Avicennia germinans ; Mangroves ; Rhizophora mangle ; biological recorder ; cellulose. ; salinity ; sea level rise ; stable isotope ratio
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0031-9422(92)83598-S
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  • 3
    Electronic Resource
    Electronic Resource
    Alterations in δ^1^3C values of seedling cellulose associated with respiration during germination
    Amsterdam : Elsevier
    Phytochemistry 35 (1994), S. 877-880 
    Details
    ISSN: 0031-9422
    Keywords: Cucurbita moschata ; Cucurbitaceae ; Gramineae ; Triticum aestivum ; Zea mays ; cellulose ; lipid ; respiration ; starch ; uncoupler. ; δ^1^3C
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0031-9422(00)90630-7
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  • 4
    Electronic Resource
    Electronic Resource
    Stable hydrogen isotope ratios of saponifiable lipids and cellulose nitrate from cam, c"3 and c"4 plants
    Amsterdam : Elsevier
    Phytochemistry 23 (1984), S. 2475-2477 
    Details
    ISSN: 0031-9422
    Keywords: Angiospermae ; cellulose nitrate ; deuterium ; hydrogen isotope ratios ; photosynthesis. ; protium ; saponifiable lipid
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0031-9422(00)84078-9
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  • 5
    Electronic Resource
    Electronic Resource
    Deuterium heterogeneity in starch and cellulose nitrate of cam and C"3 plants
    Amsterdam : Elsevier
    Phytochemistry 30 (1991), S. 1095-1098 
    Details
    ISSN: 0031-9422
    Keywords: C"3 ; CAM ; cellulose nitrate ; starch nitrate. ; δD ; δ^1^3C
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0031-9422(00)95179-3
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  • 6
    Electronic Resource
    Electronic Resource
    Gas exchange and water balance of a mistletoe species and its mangrove hosts (1989)
    Springer
    Oecologia 78 (1989), S. 176-183 
    Details
    ISSN: 1432-1939
    Keywords: Mistletoes ; Mangrove trees ; Gas exchange ; Water relations ; Carbon isotope ratios
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The gas exchange and water relations of the hemiparasite Pthirusa maritima and two its mangrove host species, Conocarpus erectus and Coccoloba uvifera, were studied in an intertidal zone of the Venezuelan coast. Carbon uptake and transpiration, leaf osmotic and total water potential, as well as nutrient content in the xylem sap and leaves of mistletoes and hosts were followed through the dry and wet season. In addition, carbon isotope ratios of leaf tissue were measured to further evaluate water use efficiency. Under similar light and humidity conditions, mistletoes had higher transpiration rates, lower leaf water potentials, and lower water use efficiencies than their hosts. Potassium content was much higher in mistletoes than in host leaves, but mineral nutrient content in the xylem sap of mistletoes was relatively low. The resistance of the liquid pathway from the soil to the leaf surface of mistletoes was larger than the total liquid flow resistance of host plants. Differences in the daily cycles of osmotic potential of the xylem sap also indicate the existence of a high resistance pathway along the vascular connection between the parasite pathway along the vascular connection between the parasite and its host. P. maritima mistletoes adjust to the different physiological characteristics of the host species which it parasitizes, thus ensuring an adequate water and carbon balance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377153
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  • 7
    Electronic Resource
    Electronic Resource
    Isotopic relationships between saponifiable lipids and cellulose nitrate prepared from red, brown and green algae (1986)
    Springer
    Planta 169 (1986), S. 320-324 
    Details
    ISSN: 1432-2048
    Keywords: Carbon isotope ratios ; Chlorophyta ; Hydrogen isotope ratios ; Isotopic relationships ; Phaeophyta ; Rhodophyta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable carbon and hydrogen isotope ratios were determined for the saponifiable lipid fraction as well as the cellulose fraction (the latter after nitration to remove exchangeable hydrogens) of several species of red, brown and green algae from three locations. A significant correlation was observed between the hydrogen isotope ratios of cellulose nitrate and saponifiable lipid for red algae, but not for brown or green algae. Carbon-13/carbon-12 ratios for both fractions of red algae were in general lower than those observed for brown and green algae. The results reported here are consistent with the proposals that red algae evolved much earlier than and are metabolically different from the brown and green algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392126
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  • 8
    Electronic Resource
    Electronic Resource
    The use of stable isotopes to study ecosystem gas exchange (2000)
    Springer
    Oecologia 123 (2000), S. 297-311 
    Details
    ISSN: 1432-1939
    Keywords: Key words Ecosystem CO2 exchange ; Ecosystem discrimination ; Oxygen-18 ; Carbon-13 ; Evapotranspiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Stable isotopes are a powerful research tool in environmental sciences and their use in ecosystem research is increasing. In this review we introduce and discuss the relevant details underlying the use of carbon and oxygen isotopic compositions in ecosystem gas exchange research. The current use and potential developments of stable isotope measurements together with concentration and flux measurements of CO2 and water vapor are emphasized. For these applications it is critical to know the isotopic identity of specific ecosystem components such as the isotopic composition of CO2, organic matter, liquid water, and water vapor, as well as the associated isotopic fractionations, in the soil-plant- atmosphere system. Combining stable isotopes and concentration measurements is very effective through the use of ”Keeling plots.” This approach allows the identification of the isotopic composition and the contribution of ecosystem, or ecosystem components, to the exchange fluxes with the atmosphere. It also allows the estimation of net ecosystem discrimination and soil disequilibrium effects. Recent modifications of the Keeling plot approach permit examination of CO2 recycling in ecosystems. Combining stable isotopes with dynamic flux measurements requires precision in isotopic sampling and analysis, which is currently at the limit of detection. Combined with the micrometeorological gradient approach (applicable mostly in grasslands and crop fields), stable isotope measurements allow separation of net CO2 exchange into photosynthetic and soil respiration components, and the evapotranspiration flux into soil evaporation and leaf transpiration. Similar applications in conjunction with eddy correlation techniques (applicable to forests, in addition to grasslands and crop fields) are more demanding, but can potentially be applied in combination with the Keeling plot relationship. The advance and potential in using stable isotope measurements should make their use a standard component in the limited arsenal of ecosystem-scale research tools.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420051016
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  • 9
    Electronic Resource
    Electronic Resource
    Photosynthesis in epiphytic and rooted Clusia rosea Jacq. (1987)
    Springer
    Oecologia 72 (1987), S. 457-460 
    Details
    ISSN: 1432-1939
    Keywords: Photosynthesis ; Hemiepiphyte ; Crassulacean acid metabolism ; Carbon isotope ratios
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Clusia rosea Jacq. is a hemiepiphyte having Crassulacean Acid Metabolism (CAM). In its natural habitat Clusia begins its life cycle as an epiphyte and eventually becomes a rooted tree. These two stages of the life cycle of Clusia represent markedly different water regimes. Our CO2 exchange, stomatal conductance, titratable acidity, and stable carbon isotope ratio measurements indicate that Clusia has a flexible photosynthetic mode, where CO2 is fixed mostly via CAM during its epiphytic stage, when water availability is low, and via both CAM and C3 during its rooted stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377579
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  • 10
    Electronic Resource
    Electronic Resource
    Stable carbon isotope ratio of tree leaves, boles and fine litter in a tropical forest in Rondônia, Brazil (1998)
    Springer
    Oecologia 114 (1998), S. 170-179 
    Details
    ISSN: 1432-1939
    Keywords: Key words Amazon ; Vegetation ; Forest ; Stable carbon isotope ; Rondônia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaves of 208 trees were collected for isotopic analysis together with wood from 36 tree boles and 18 samples of fine litter from a terra-firme forest located at Samuel Ecological Reserve, Rondônia State, in the southwestern Amazon region. The range of δ13C values in leaves was from −28 to −36‰, with an average (±1 SD) of −32.1 ± 1.5‰, which was more negative than the δ13C values of bole samples (−28.4 ± 2.0‰) and fine litter (−28.7 ± 2.0‰). These values are within the range found for tropical and subtropical forests. Pooling the δ13C values for leaf samples from trees of the same height gave averages which were positively correlated with plant height at a highly significant level, with a slope of 0.06 and an intercept of −33.3‰ and a correlation coefficient r 2=0.70 (P〈0.001).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050433
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