scholarly journals Paleovegetation reconstruction using <i>δ</i><sup>13</sup>C of Soil Organic Matter

2008 ◽  
Vol 5 (2) ◽  
pp. 1795-1823 ◽  
Author(s):  
G. Wang ◽  
X. Feng ◽  
J. Han ◽  
L. Zhou ◽  
W. Tan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Negative Relationship ◽  
C4 Plants ◽  
Chinese Loess Plateau ◽  
C3 Plants ◽  
Soil Profiles ◽  
Chinese Loess ◽  
Δ13c Value ◽  
Sample Reconstruction

Abstract. The relative contributions of C3 and C4 plants to vegetation at a given locality may be estimated by means of δ13C of soil organic matter. This approach holds great potential for paleoecological reconstruction using paleosols. However, two uncertainties exist, which limits the accuracy of this application. One is 13C enrichment as plant carbon becomes incorporated into soil organic matter. The other is due to environmental influences on δ13C of plants. Two types of data were collected and analyzed with an objective of narrowing the error of paleovegetation reconstruction. First, we investigated δ13C variations of 557 C3 and 136 C4 plants along a precipitation gradient in North China. A strong negative relationship is found between the δ13C value of C3 plants averaged for each site and the annual precipitation with a coefficient of −0.40‰/100 mm, while no significant coefficients were found for C4 plants. Second, we measured δ13C of soil organic matters for 14 soil profiles at three sites. The isotopic difference between vegetation and soil organic matter are evaluated to be 1.8‰ for the surface soil and 2.8‰ for the soil at the bottom of soil profiles. Using the new data we conducted a sample reconstruction of paleovegetation at the central Chinese Loess Plateau during the Holocene and the Last Glaciation, and conclude that, without corrections for 13C enrichment by decomposition, the C4 abundance would be overestimated. The importance and uncertainties of other corrections are also discussed.

scholarly journals Paleovegetation reconstruction using δ<sup>13</sup>C of Soil Organic Matter

2008 ◽  
Vol 5 (5) ◽  
pp. 1325-1337 ◽  
Author(s):  
G. Wang ◽  
X. Feng ◽  
J. Han ◽  
L. Zhou ◽  
W. Tan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
C4 Plants ◽  
Chinese Loess Plateau ◽  
C3 Plants ◽  
Soil Profiles ◽  
Strong Negative Correlation ◽  
Chinese Loess ◽  
Δ13c Value ◽  
Sample Reconstruction

Abstract. The relative contributions of C3 and C4 plants to vegetation at a given locality may be estimated by means of δ13C of soil organic matter. This approach holds a great potential for paleoecological reconstruction using paleosols. However, two main uncertainties exist, which limits the accuracy of this application. One is δ13C-enrichment as the plant carbon becomes incorporated into soil organic matter. The other is due to environmental influences on δ13C of plants. Two types of data were collected and analyzed with an objective of narrowing the error of paleovegetation reconstruction. First, we investigated δ13C variations of 557 C3 and 136 C4 plants along a precipitation gradient in North China. A strong negative correlation is found between the δ13C value of C3 plants averaged for each site and the annual precipitation with a coefficient of −0.40‰/100mm, while no significant coefficients were found for C4 plants. Second, we measured δ13C of soil organic matters for 14 soil profiles at three sites. The isotopic difference between vegetation and soil organic matter are evaluated to be 1.8‰ for the surface soil and 2.8‰ for the soil at the bottom of soil profiles. We conducted a sample reconstruction of paleovegetation at the central Chinese Loess Plateau during the Holocene and the Last Glacial (LG), and conclude that, without corrections for δ13C-enrichment by decomposition, the C4 abundance would be overestimated. The importance and uncertainties of other corrections are also discussed.

Aridity-driven decoupling of δ13C between pedogenic carbonate and soil organic matter

Geology ◽  
2020 ◽  
Vol 48 (10) ◽  
pp. 981-985 ◽  
Author(s):  
Jiawei Da ◽  
Yi Ge Zhang ◽  
Gen Li ◽  
Junfeng Ji
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Pore Space ◽  
C4 Plants ◽  
Atmospheric Co2 ◽  
Chinese Loess Plateau ◽  
Pedogenic Carbonate ◽  
Chinese Loess ◽  
Pedogenic Carbonates ◽  
Soil Pore Space

Abstract Pedogenic carbonate is an invaluable archive for reconstructing continental paleoclimate and paleoecology. The δ13C of pedogenic carbonate (δ13Cc) has been widely used to document the rise and expansion of C4 plants over the Cenozoic. This application requires a fundamental presumption that in soil pores, soil-respired CO2 dominates over atmospheric CO2 during the formation of pedogenic carbonates. However, the decoupling between δ13Cc and δ13C of soil organic matter (δ13CSOM) have been observed, particularly in arid regions, suggesting that this presumption is not always valid. To evaluate the influence of atmospheric CO2 on soil δ13Cc, here we performed systematic δ13C analyses of paleosols across the Chinese Loess Plateau, with the sample ages spanning three intervals: the Holocene, the Late Pleistocene, and the mid-Pliocene warm period. Our paired δ13Cc and δ13CSOM data reveal broadly divergent trending patterns. Using a two-component CO2-mixing model, we show substantial incorporations of atmospheric CO2 (up to 60%) into soil pore space during carbonate precipitation. This result readily explains the enrichment of δ13Cc and its divergence from δ13CSOM. As a consequence, δ13C of pedogenic carbonates formed under semiarid and/or arid conditions are largely driven by regional aridity through its control on soil CO2 composition, and thus cannot be used to evaluate the relative abundance of C3 versus C4 plants. Nonetheless, these carbonates can be applied for atmospheric CO2 reconstructions, even for periods with low CO2 levels.

Multi-scale spatial relationships between soil organic matter and influencing factors in basins of the Chinese Loess Plateau

2017 ◽  
Vol 37 (24) ◽  
Author(s):  
朱洪芬 ZHU Hongfen ◽  
南锋 NAN Feng ◽  
徐占军 XU Zhanjun ◽  
荆耀栋 JING Yaodong ◽  
段永红 DUAN Yonghong ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Influencing Factors ◽  
Loess Plateau ◽  
Chinese Loess Plateau ◽  
Spatial Relationships ◽  
Chinese Loess ◽  
Multi Scale ◽  
The Chinese Loess Plateau

Reconsidering the paleoclimate implications of magnetic susceptibility records of Holocene loessic soils

2021 ◽  
Author(s):  
Diana Jordanova ◽  
Neli Jordanova
Keyword(s):  
Magnetic Susceptibility ◽  
Parent Material ◽  
Chinese Loess Plateau ◽  
Absolute Difference ◽  
Physical Parameters ◽  
Soil Profiles ◽  
Chinese Loess ◽  
Loess Area ◽  
River Terraces ◽  
Paleoclimate Proxy

&lt;p&gt;Mass specific magnetic susceptibility variations with depth along soil profiles developed on loess parent material is one of the most frequently used physical parameters in local, regional and global correlations of loess deposits. It is also utilized as a paleo-precipitation proxy, defined either as absolute difference between susceptibilities of the enhanced B-horizon and parent loess, or as relative enhancement using ratios of magnetic parameters. These different approaches in the application of magnetic susceptibility as paleoclimate proxy lead us to perform a comparative study on a number of Holocene soil profiles developed on loess from European loess area and the Chinese Loess Plateau (CLP). We made a compilation of data including 20 profiles from North Bulgaria, 28 profiles from Eastern and Central Europe; and 26 profiles from the CLP. Minimum magnetic susceptibilities of the last glacial loess (X&lt;sub&gt;min&lt;/sub&gt;) from the compiled data base for European and Chinese profiles show climate related variability, revealing multi linear relationship with both present day MAP and MAT values for the corresponding locations. Strong deviations of X&lt;sub&gt;min&lt;/sub&gt; from this dependence display sites located at low elevation river terraces, Black sea coast and possessing large content of coarse silt and sand fractions. Pedogenic magnetic susceptibility (X&lt;sub&gt;pedo&lt;/sub&gt;) defined as (X&lt;sub&gt;max&lt;/sub&gt; - X&lt;sub&gt;min&lt;/sub&gt;) with&amp;#160; X&lt;sub&gt;max&lt;/sub&gt; determined from the youngest part (last 1500 &amp;#8211; 2000 years B.P.) of the Holocene magnetic susceptibility records of Chinese sections and absolute X&lt;sub&gt;max&lt;/sub&gt; of the European sites show systematic dependence on modern MAP and MAT values. This dependence is uniform for all sites with steppe vegetation, while higher scatter and steeper regression trends are observed for sites under mixed (steppe &amp;#8211; forest) and forest vegetation. The study is financially supported by project No KP-06-N34/2 funded by the Bulgarian National Science Fund.&lt;/p&gt;

scholarly journals Radiocarbon Dating of Total Soil Organic Matter and Humin Fraction and Its Comparison with 14C Ages of Fossil Charcoal

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 595-601 ◽  
Author(s):  
L C R Pessenda ◽  
S E M Gouveia ◽  
R Aravena
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Radiocarbon Dating ◽  
Natural Vegetation ◽  
Soil Profiles ◽  
North Central ◽  
Total Soil ◽  
Experimental Errors ◽  
Humin Fraction

During the last decade radiocarbon dating has been used extensively in distinct regions of Brazil to provide information about soil chronology in paleoenvironmental studies. This paper presents 14C data of soil organic matter (SOM), humin fraction, and charcoal in several soil profiles under natural vegetation from different Brazil locations (north, central, and southeast regions). The main objective is to compare the obtained 14C dating of total SOM with humin, the oldest fraction of SOM. In order to validate the humin ages these data are compared with the age of charcoal collected at similar depths. The 14C ages obtained on charcoal were, in most of the cases, in agreement with the humin fraction considering the experimental errors, or 20% older in average. The dates obtained from total SOM showed significantly younger ages than the humin fraction indicating contamination by younger carbon. These results show the humin fraction is considered a reliable material for 14C dating in soils. However, the humin fraction ages could be assumed as the minimum ages for carbon in soils.

Elevated Atmosphere Partial Pressure of CO2 and Plant Growth. III. Interactions Between Triticum aestivum (C3) and Echinochloa frumentacea (C4) During Growth in Mixed Culture Under Different CO2, N Nutrition and Irradiance Treatments, With Emphasis on Below-Ground Responses Estimated Using the δ13C Value of Root Biomass

1991 ◽  
Vol 18 (2) ◽  
pp. 137 ◽  
Author(s):  
SC Wong ◽  
CB Osmond
Keyword(s):  
Triticum Aestivum ◽  
Mixed Culture ◽  
Elevated Co2 ◽  
Root Biomass ◽  
Shoot Growth ◽  
Mixed Cultures ◽  
C4 Plants ◽  
C3 Plants ◽  
Δ13c Value ◽  
Echinochloa Frumentacea

Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species, were grown in pots in monoculture and mixed culture (2 C3 : 1 C4 and 1 C3:2 C4) at two ambient partial pressures of CO2 (320 and 640 μbar), two photosynthetic photon flux densities (PPFDs) (daily maximum 2000 and 500 �mol m-2 s-1) and two levels of nitrogen nutrition (12 mM and 2 mM NO3-). Growth of shoots of both components in mixed culture was measured by physical separation, and the proportions of root biomass due to each component were calculated from δ13C value of total root biomass. In air (320 μbar CO2) at high PPFD and with high root zone-N, the shoot biomass of C3 and C4 components at the first harvest (28 days) was in proportion to the sowing ratio. However, by the second harvest (36 days) the C4 component predominated in both mixtures. Under the same conditions, but with low PPFD, C3 plants predominated at the first harvest but C4 plants had over- taken them by the time of the second harvest. Elevated atmospheric CO2 (640 μbar) stimulated shoot growth of Triticum in 15 of 16 treatment combinations and the stimulation was greatest in plants provided with low NO3-. Root growth of the C3 plants was generally stimulated by elevated CO2, but was only occasionally sensitive to the presence of C4 plants in mixed culture. However, growth of the C4 plants was often sensitive to the presence of C3 plants in mixed culture. In mixed cultures, elevated CO2 plants stimulated growth of C4 plants at high PPFD, high-N and in all low-N treatments but this was insufficient to offset a marked decline in shoot growth with increasing proportion of C3 plants in mixed cultures. The unexpected stimulation of growth of C4 plants by elevated CO2 was correlated with more negative δ13C values of C4 root biomass, suggesting a partial failure of the CO2 concentrating mechanism of C4 photosynthesis in Echinochloa under low-N. These experiments show that for these species nitrogen was more important than light or elevated pCO2 in determining the extent of competitive interactions in mixed culture.

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