scholarly journals Diel variations in the carbon isotope composition of respired CO<sub>2</sub> and associated carbon sources: a review of dynamics and mechanisms

2011 ◽  
Vol 8 (2) ◽  
pp. 2183-2233 ◽  
Author(s):  
C. Werner ◽  
A. Gessler
Keyword(s):  
Carbon Isotope ◽  
Temporal Dynamics ◽  
Carbon Allocation ◽  
Ecosystem Respiration ◽  
Isotope Composition ◽  
Carbon Sources ◽  
Mechanistic Explanation ◽  
Short Term ◽  
Theoretical Understanding ◽  
Plant Soil

Abstract. Recent advances have improved our methodological approaches and theoretical understanding of post-photosynthetic carbon isotope fractionation. Nevertheless we still lack a clear picture of the origin of short-term variability in δ13C of respired CO2 (δ13Cres) and organic carbon fractions on a diel basis. However, closing this knowledge gap is essential for the application of stable isotope approaches for partitioning ecosystem respiration, tracing carbon flow through plants and ecosystems and disentangling key physiological processes in carbon metabolism of plants. In this review we examine the short-term dynamics in δ13Cres and putative substrate pools at the plant, soil and ecosystem scales and develop mechanistic explanations for diel δ13Cres dynamics at each scale. Maximum reported variation in diel δ13Cres is 4.0, 5.4 and 14.8‰ in trunks, roots and leaves of different species and 12.5 and 8.1‰ at the soil and ecosystem scale in different biomes. Temporal variation in post-photosynthetic fractionation related to changes in carbon allocation to different metabolic pathways is the most plausible mechanistic explanation for observed diel dynamics in δ13Cres. In addition, mixing of component fluxes with different temporal dynamics and isotopic compositions add to the δ13Cres variation on the soil and ecosystem level. Understanding short-term variations in δ13Cres is particularly important for ecosystem studies, since δ13Cres contains information on the fate of respiratory substrates, and may, therefore, provide a non-intrusive way to identify changes in carbon allocation patterns.

scholarly journals Diel variations in the carbon isotope composition of respired CO<sub>2</sub> and associated carbon sources: a review of dynamics and mechanisms

2011 ◽  
Vol 8 (9) ◽  
pp. 2437-2459 ◽  
Author(s):  
C. Werner ◽  
A. Gessler
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Temporal Dynamics ◽  
Carbon Allocation ◽  
Ecosystem Respiration ◽  
Isotope Composition ◽  
Carbon Sources ◽  
Mechanistic Explanation ◽  
Short Term ◽  
Theoretical Understanding

Abstract. Recent advances have improved our methodological approaches and theoretical understanding of post-photosynthetic carbon isotope fractionation processes. Nevertheless we still lack a clear picture of the origin of short-term variability in δ13C of respired CO2 (δ13Cres) and organic carbon fractions on a diel basis. Closing this knowledge gap is essential for the application of stable isotope approaches for partitioning ecosystem respiration, tracing carbon flow through plants and ecosystems and disentangling key physiological processes in carbon metabolism of plants. In this review we examine the short-term dynamics in δ13Cres and putative substrate pools at the plant, soil and ecosystem scales and discuss mechanisms, which might drive diel δ13Cres dynamics at each scale. Maximum reported variation in diel δ13Cres is 4.0, 5.4 and 14.8 ‰ in trunks, roots and leaves of different species and 12.5 and 8.1 ‰ at the soil and ecosystem scale in different biomes. Temporal variation in post-photosynthetic isotope fractionation related to changes in carbon allocation to different metabolic pathways is the most plausible mechanistic explanation for observed diel dynamics in δ13Cres. In addition, mixing of component fluxes with different temporal dynamics and isotopic compositions add to the δ13Cres variation on the soil and ecosystem level. Understanding short-term variations in δ13Cres is particularly important for ecosystem studies, since δ13Cres contains information on the fate of respiratory substrates, and may, therefore, provide a non-intrusive way to identify changes in carbon allocation patterns.

Short-Term Measurements of Carbon Isotope Discrimination in Several C4 Species

1992 ◽  
Vol 19 (3) ◽  
pp. 263 ◽  
Author(s):  
SA Henderson ◽  
SV Caemmerer ◽  
GD Farquhar
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Isotope Composition ◽  
Leaf Gas Exchange ◽  
Short Term ◽  
Isotope Discrimination ◽  
C4 Species ◽  
Linear Relationships ◽  
Partial Pressures ◽  
Wide Range

Carbon isotope discrimination (Δ) and leaf gas-exchange were measured simultaneously for a number of C4 species. Linear relationships were found between A and the ratio of intercellular to ambient partial pressures of CO2, pI/pa. These data were used to estimate the fraction of CO2 released by C4-acid decarboxylation in the bundle sheath, which subsequently leaks out to the mesophyll. We define this fraction as the leakiness of the system and it is also a measure of the extent to which phosphoenolpyruvate (PEP) carboxylations exceed ribulose 1,5-bisphosphate (RuBP) carboxylations. For Sorghum bicolor and Amaranthus edulis, leakiness was estimated at 0.2 and was constant over a wide range of irradiances (between 480 and 1600 μmol quanta m-2 s-1), intercellular CO2 pressures (between 30 and 350 μbar) and leaf temperatures (from 21�C to 34�C). At irradiances less than 240 μmol quanta m-2 s-1, leakiness appeared to increase. For a number of dicotyledonous and monocotyledonous species, of the various C4-decarboxylation types, leakiness was also estimated at 0.2. Contrary to expectation, amongst the 11 species examined, those with suberised lamellae did not show lower values of leakiness than those without suberised lamellae. For one NAD-ME and one PCK monocot, the estimates of leakiness were significantly higher at 0.30 and 0.25, respectively. Long-term discrimination (assessed from carbon isotope composition of leaf dry matter) did not correlate well with these short- term measures of discrimination. We suggest that this may be due to differences between species in fractionations occurring after photosynthesis.

Temporal dynamics of the carbon isotope composition in a Pinus sylvestris stand: from newly assimilated organic carbon to respired carbon dioxide

Oecologia ◽  
2008 ◽  
Vol 156 (4) ◽  
pp. 737-750 ◽  
Author(s):  
Naomi Kodama ◽  
Romain L. Barnard ◽  
Yann Salmon ◽  
Christopher Weston ◽  
Juan Pedro Ferrio ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Organic Carbon ◽  
Pinus Sylvestris ◽  
Carbon Isotope ◽  
Temporal Dynamics ◽  
Isotope Composition ◽  
Carbon Isotope Composition

scholarly journals Importance of short-term dynamics in carbon isotope ratios of ecosystem respiration (?13CR) in a Mediterranean oak woodland and linkage to environmental factors

2006 ◽  
Vol 172 (2) ◽  
pp. 330-346 ◽  
Author(s):  
Christiane Werner ◽  
Stephan Unger ◽  
João S. Pereira ◽  
Rodrigo Maia ◽  
Teresa S. David ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Carbon Isotope ◽  
Ecosystem Respiration ◽  
Isotope Ratios ◽  
Oak Woodland ◽  
Short Term ◽  
Carbon Isotope Ratios

Short-term changes in carbon isotope composition of soluble carbohydrates and starch: from canopy leaves to the root system

2006 ◽  
Vol 20 (4) ◽  
pp. 653-660 ◽  
Author(s):  
Sabine Göttlicher ◽  
Alexander Knohl ◽  
Wolfgang Wanek ◽  
Nina Buchmann ◽  
Andreas Richter
Keyword(s):  
Root System ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Carbon Isotope Composition ◽  
Soluble Carbohydrates ◽  
Short Term

The carbon-isotope signature of diagenetic carbonates

2020 ◽  
Author(s):  
Patrick Meister ◽  
Carolina Reyes
Keyword(s):  
Carbon Isotope ◽  
Reactive Transport ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Isotope Composition ◽  
Carbon Sources ◽  
Deep Biosphere ◽  
Transport Modelling ◽  
Isotope Signature ◽  
Carbonate Formation

&lt;p&gt;Diagenetic carbonates often show large variations in their carbon isotope compositions. Variations are mainly the result of isotope fractionation effects during microbial metabolic processes, and these processes themselves may induce carbonate formation. Inorganic carbon from dissimilatory microbial activity shows negative carbon isotope values (d&lt;sup&gt;13&lt;/sup&gt;C), in particular if methane is used as a carbon source. In turn, inorganic carbon produced during methanogenesis shows positive d&lt;sup&gt;13&lt;/sup&gt;C values. The range of isotope values preserved in the carbonate phase ultimately depends on the reservoir sizes, diffusive mixing of different carbon sources, and episodic formation of carbonate (Meister et al., 2019; Meister and Reyes, 2019). The carbon-isotope signature of diagenetic carbonates therefore represents an archive of past biogeochemical activity in the subsurface.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Meister, P. and Reyes, C. (2019) The carbon-isotope record of the sub-seafloor biosphere. In: &quot;Tracking the Deep Biosphere through Time&quot; (Eds. H. Drake, M. Ivarsson, C. Heim), Geosciences 9, 507, 1-25. https://doi:10.3390/geosciences9120507&lt;/p&gt;&lt;p&gt;Meister, P., Liu, B., Khalili, A., B&amp;#246;ttcher, M.E., and J&amp;#248;rgensen, B.B. (2019) Factors controlling the carbon isotope composition of dissolved inorganic carbon and methane in marine porewater: An evaluation by reactive-transport modelling. J. Marine Systems 200, 103227, 1-18. https://doi.org/10.1016/j.jmarsys.2019.103227&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Economic conditions and perceptions of immigrants as an economic threat in Europe: Temporal dynamics and mediating processes

2021 ◽  
pp. 002071522199352
Author(s):  
Boris Heizmann ◽  
Nora Huth
Keyword(s):  
Temporal Dynamics ◽  
European Social Survey ◽  
Primary Objective ◽  
Conflict Theory ◽  
Economic Conditions ◽  
Political Climate ◽  
Short Term ◽  
Economic Threat ◽  
Party Positions

This article addresses the extent to which economic downturns influence the perception of immigrants as an economic threat and through which channels this occurs. Our primary objective is an investigation of the specific mechanisms that connect economic conditions to the perception of immigrants as a threat. We therefore also contribute to theoretical discussions based on group threat and realistic group conflict theory by exposing the dominant source of competition relevant to these relationships. Furthermore, we investigate whether people react more sensitive to short-term economic dynamics within countries than to the long-term economic circumstances. Our database comprises all waves of the European Social Survey from 2002 to 2017. The macro-economic indicators we use include GDP per capita, unemployment, and national debt levels, covering the most salient economic dimensions. We furthermore control for the country’s migration situation and aggregate party positions toward cultural diversity. Our results show that the dynamic short-term developments of the economy and migration within countries are of greater relevance for perceived immigrant threat than the long-term situation. In contrast, the long-term political climate appears to be more important than short-term changes in the aggregate party positions. Further mediation analyses show that objective economic conditions influence anti-immigrant attitudes primarily through individual perceptions of the country’s economic performance and that unemployment rates are of primary importance.

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