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Title: Scale and the Isotopic Record of C4 Plants in Peogenic Carbonate - Biome to Rhizosphere

Abstract

The {sup 13}C/{sup 12}C ratio in pedogenic carbonate (i.e., CaCO{sub 3} formed in soil) is a significant tool for investigating C{sub 4} biomes of the past. However, the paleoecological meaning of {delta}{sup 13}C values in pedogenic carbonate can change with the scale at which one considers the data. We describe studies of modern soils, fossil soils, and vegetation change in the Chihuahuan Desert of North America and elsewhere that reveal four scales important for paleoecologic interpretations. (1) At the broadest scale, the biome scale (hundreds to millions of km{sup 2}), an isotopic record interpreted as C{sub 3} vegetation replacing C{sub 4} grasslands may indicate invading C{sub 3} woody shrubs instead of expanding C{sub 3} forests (a common interpretation). (2) At the landscape scale (several tens of m{sup 2} to hundreds of km{sup 2}), the accuracy of scaling up paleoclimatic interpretations to a regional level is affected by the landform containing the isotopic record. (3) At the soil-profile scale (cm{sup 2} to m{sup 2}), soil profiles with multiple generations of carbonate mixed together have a lower-resolution paleoecologic record than soil profiles repeatedly buried. (4) At the rhizosphere scale ({mu}m{sup 2} to cm{sup 2}), carbonate formed on roots lack the 14-17{per_thousand} enrichmentmore » observed at broader scales, revealing different fractionation processes at different scales. A multi-scale approach in dealing with {delta}{sup 13}C in pedogenic carbonate will increase the accuracy of paleoecologic interpretations and understanding of soil-geomorphic-climatic interactions that affect boundaries between C{sub 4} and C{sub 3} vegetation.« less

Authors:
 [1];  [2];  [3];  [4]
  1. New Mexico State University, Las Cruces
  2. ORNL
  3. University of Nevada, Las Vegas
  4. Sant fe Water Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1021946
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Nature
Additional Journal Information:
Journal Volume: 368; Journal Issue: 6471; Journal ID: ISSN 0012-9658
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ACCURACY; CARBON ISOTOPES; CARBON 12; CARBON 13; CARBONATES; DATA; DESERTS; ENRICHMENT; FORESTS; FOSSILS; FRACTIONATION; GEOMORPHOLOGY; INTERACTIONS; NEW MEXICO; NORTH AMERICA; PLANTS; RANGELANDS; ROOTS; SCALING; SHRUBS; SOILS; Isotopes; Scale; Biome; Pedogenic Carbonate

Citation Formats

Monger, Dr. H Curtis, Cole, David R, Buck, Dr. Brenda, and Gallegos, Robert. Scale and the Isotopic Record of C4 Plants in Peogenic Carbonate - Biome to Rhizosphere. United States: N. p., 1994. Web.
Monger, Dr. H Curtis, Cole, David R, Buck, Dr. Brenda, & Gallegos, Robert. Scale and the Isotopic Record of C4 Plants in Peogenic Carbonate - Biome to Rhizosphere. United States.
Monger, Dr. H Curtis, Cole, David R, Buck, Dr. Brenda, and Gallegos, Robert. 1994. "Scale and the Isotopic Record of C4 Plants in Peogenic Carbonate - Biome to Rhizosphere". United States.
@article{osti_1021946,
title = {Scale and the Isotopic Record of C4 Plants in Peogenic Carbonate - Biome to Rhizosphere},
author = {Monger, Dr. H Curtis and Cole, David R and Buck, Dr. Brenda and Gallegos, Robert},
abstractNote = {The {sup 13}C/{sup 12}C ratio in pedogenic carbonate (i.e., CaCO{sub 3} formed in soil) is a significant tool for investigating C{sub 4} biomes of the past. However, the paleoecological meaning of {delta}{sup 13}C values in pedogenic carbonate can change with the scale at which one considers the data. We describe studies of modern soils, fossil soils, and vegetation change in the Chihuahuan Desert of North America and elsewhere that reveal four scales important for paleoecologic interpretations. (1) At the broadest scale, the biome scale (hundreds to millions of km{sup 2}), an isotopic record interpreted as C{sub 3} vegetation replacing C{sub 4} grasslands may indicate invading C{sub 3} woody shrubs instead of expanding C{sub 3} forests (a common interpretation). (2) At the landscape scale (several tens of m{sup 2} to hundreds of km{sup 2}), the accuracy of scaling up paleoclimatic interpretations to a regional level is affected by the landform containing the isotopic record. (3) At the soil-profile scale (cm{sup 2} to m{sup 2}), soil profiles with multiple generations of carbonate mixed together have a lower-resolution paleoecologic record than soil profiles repeatedly buried. (4) At the rhizosphere scale ({mu}m{sup 2} to cm{sup 2}), carbonate formed on roots lack the 14-17{per_thousand} enrichment observed at broader scales, revealing different fractionation processes at different scales. A multi-scale approach in dealing with {delta}{sup 13}C in pedogenic carbonate will increase the accuracy of paleoecologic interpretations and understanding of soil-geomorphic-climatic interactions that affect boundaries between C{sub 4} and C{sub 3} vegetation.},
doi = {},
url = {https://www.osti.gov/biblio/1021946}, journal = {Nature},
issn = {0012-9658},
number = 6471,
volume = 368,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 1994},
month = {Sat Jan 01 00:00:00 EST 1994}
}