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Elevated CO2 did not mitigate the effect of a short-term drought on biological soil crusts

Biology and Fertility of Soils

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Abstract

Biological soil crusts (biocrusts) are critical components of arid and semi-arid ecosystems that contribute significantly to carbon (C) and nitrogen (N) fixation, water retention, soil stability, and seedling recruitment. While dry-land ecosystems face a number of environmental changes, our understanding of how biocrusts may respond to such perturbation remains notably poor. To determine the effect that elevated CO2 may have on biocrust composition, cover, and function, we measured percent soil surface cover, effective quantum yield, and pigment concentrations of naturally occurring biocrusts growing in ambient and elevated CO2 at the desert study site in Nevada, USA, from spring 2005 through spring 2007. During the experiment, a year-long drought allowed us to explore the interacting effects that elevated CO2 and water availability may have on biocrust cover and function. We found that, regardless of CO2 treatment, precipitation was the major regulator of biocrust cover. Drought reduced moss and lichen cover to near-zero in both ambient and elevated CO2 plots, suggesting that elevated CO2 did not alleviate water stress or increase C fixation to levels sufficient to mitigate drought-induced reduction in cover. In line with this result, lichen quantum yield and soil cyanobacteria pigment concentrations appeared more strongly dependent upon recent precipitation than CO2 treatment, although we did find evidence that, when hydrated, elevated CO2 increased lichen C fixation potential. Thus, an increase in atmospheric CO2 may only benefit biocrusts if overall climate patterns shift to create a wetter soil environment.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Elevated CO2 did not mitigate the effect of a short-term drought on biological soil crusts
Series title:
Biology and Fertility of Soils
Volume
48
Issue:
7
Year Published:
2012
Language:
English
Publisher:
Springer
Publisher location:
Amsterdam, Netherlands
Contributing office(s):
Southwest Biological Science Center
Description:
9 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Biology and Fertility of Soils
First page:
797
Last page:
805