Soil biota responses to long-term atmospheric CO2 enrichment in two California annual grasslands |
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Authors: | Matthias C Rillig Christopher B Field Michael F Allen |
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Institution: | (1) Carnegie Institution of Washington, Department of Plant Biology, 260 Panama Street, Stanford, CA 94305, USA e-mail: matthias@jasper.stanford.edu, Fax: +1-650-3256857, PA;(2) Center for Conservation Biology, University of California, Riverside, CA 92521-0334, USA, US |
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Abstract: | Root, arbuscular-mycorrhizal (AM), soil faunal (protozoa and microarthropods), and microbial responses to field exposure
to CO2 for six growing seasons were measured in spring 1997 in two adjacent grassland communities. The grasslands showed contrasting
root responses to CO2 enrichment: whereas root length was not affected in the sandstone grassland, it was greater in the serpentine grassland,
as was specific root length. AM fungal hyphal lengths were greater in the sandstone, but were unaffected in the serpentine
community. This lent support to the hypothesis that there may be a tradeoff in resource allocation to more fine roots or greater
mycorrhizal extraradical hyphal length. AM root infection was greater in both communities at elevated CO2, as was the proportion of roots containing arbuscules. Our data on total hyphal lengths, culturable and active fungi, bacteria,
and protozoa supported the hypothesis that the fungal food chain was more strongly stimulated than the bacterial chain. This
study is one of the first to test these hypotheses in natural multi-species communities in the field.
Received: 23 October 1998 / Accepted: 19 February 1999 |
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Keywords: | Root Hyphae Arbuscular-mycorrhizae Food web Grasslands |
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