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Climate controls on C3 vs. C4 productivity in North American grasslands from carbon isotope composition of soil organic matter

Global Change Biology

By:
, ,
DOI: 10.1111/j.1365-2486.2008.01552.x

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Abstract

We analyzed the ??13 C of soil organic matter (SOM) and fine roots from 55 native grassland sites widely distributed across the US and Canadian Great Plains to examine the relative production of C3 vs. C4 plants (hereafter %C4) at the continental scale. Our climate vs. %C4 results agreed well with North American field studies on %C4, but showed bias with respect to %C4 from a US vegetation database (statsgo) and weak agreement with a physiologically based prediction that depends on crossover temperature. Although monthly average temperatures have been used in many studies to predict %C4, our analysis shows that high temperatures are better predictors of %C4. In particular, we found that July climate (average of daily high temperature and month's total rainfall) predicted %C4 better than other months, seasons or annual averages, suggesting that the outcome of competition between C3 and C4 plants in North American grasslands was particularly sensitive to climate during this narrow window of time. Root ??13 C increased about 1??? between the A and B horizon, suggesting that C 4 roots become relatively more common than C3 roots with depth. These differences in depth distribution likely contribute to the isotopic enrichment with depth in SOM where both C3 and C4 grasses are present. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Climate controls on C3 vs. C4 productivity in North American grasslands from carbon isotope composition of soil organic matter
Series title:
Global Change Biology
DOI:
10.1111/j.1365-2486.2008.01552.x
Volume
14
Issue:
5
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1141
Last page:
1155
Number of Pages:
15