نتایج جستجو برای: carbon isotope discrimination delta
تعداد نتایج: 423589 فیلتر نتایج به سال:
We analysed two groups of Quercus robur trees, growing at nearby plots with different micro-location condition (W-wet and D-dry) in the floodplain Krakovo forest, Slovenia. In the study we compared the growth response of two different tree groups to environmental variables, the potential signal stored in earlywood (EW) structure and the potential difference of the information stored in carbon i...
Carbon isotope fractionation in metabolic processes following carboxylation of ribulose-1,5-bisphosphate (RuBP) is not as well described as the discrimination during photosynthetic CO(2) fixation. However, post-carboxylation fractionation can influence the diel variation of delta(13)C of leaf-exported organic matter and can cause inter-organ differences in delta(13)C. To obtain a more mechanist...
Stable isotope analysis of feces can provide a non-invasive method for tracking the dietary habits of nearly any mammalian species. While fecal samples are often collected for macroscopic and genetic study, stable isotope analysis can also be applied to expand the knowledge of species-specific dietary ecology. It is somewhat unclear how digestion changes the isotope ratios of animals' diets, so...
The stable carbon isotope compositions of tetrols, erythritol and threitol were determined by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using four tetrols with various delta(13)C values derivatized by methylboronic acid, the carbon isotope analysis method achieved excellent reproducibility and high accuracy. There was no carbon isotopic fractionation during the ...
Variable retention harvesting (VRH) has been proposed as a silvicultural practice to maintain biodiversity and ecosystem integrity. No previous study has examined tree carbon isotope discrimination to provide insights into water stress that could lead to dieback and mortality of trees following VRH. We measured and compared the carbon isotope ratios (delta(13)C) in stem wood of trembling aspen ...
Isotope ratio analyses of atmospheric CO(2) at natural abundance have significant potential for contributing to our understanding of photosynthetic and respiration processes in forest ecosystems. Recent advances in isotope ratio mass spectrometry allow for rapid, on-line analysis of small volumes of CO(2) in air, and open new research opportunities at the ecophysiological, whole-organism, and a...
The ratio of carbon accumulation to transpiration, W, of wheat (Triticum aestivum L.) seedlings increased with increasing soil strength, measured as soil penetrometer resistance, and this was already apparent at the two leaf stage. The ratio was negatively correlated with carbon isotope discrimination, in accord with theory. This means that decrease in intercellular partial pressure of CO(2) ac...
The carbon isotope composition of photosynthetic organisms reflects the (delta)(sup13)C of their inorganic carbon sources. The large difference between (delta)(sup13)C in cyanobacterial surface scums (-25 to -18(permil)) and subsurface blooms (-34 to -30(permil)) in a subarctic lake indicates direct atmospheric CO(inf2) fixation by the scums.
Fossil leaves assigned to the genus Ginkgo are increasingly being used to reconstruct Mesozoic and Tertiary environments based on their stomatal and carbon isotopic characteristics. We sought to provide a more secure basis for understanding variations seen in the plant fossil record by determining the natural variability of these properties of sun and shade leaf morphotypes of Ginkgo biloba tre...
The characteristic decline in height growth that occurs over a tree's lifespan is often called "age-related decline." But is the reduction in height growth in aging trees a function of age or of size? We grafted shoot tips across different ages and sizes of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees to determine whether the decline in height growth is mediated by tree size or by t...
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