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CO2 efflux from a Mediterranean semi-arid forest soil. I. Seasonality and effects of stoniness

Authors
  • Casals, Pere1
  • Romanyà, Joan1
  • Cortina, Jordi2
  • Bottner, Pierre3
  • Coûteaux, Marie-Madeleine3
  • Vallejo, V. Ramon1, 4
  • 1 Universitat de Barcelona, Department Biologia Vegetal, Diagonal, 645, Barcelona, 08028, Spain , Barcelona
  • 2 Universitat d' Alacant', Department Ecologia, Alacant, Spain , Alacant
  • 3 CEFE-CNRS, 1919 Route de Mende, Montpellier Cedex 5, 33293, France , Montpellier Cedex 5
  • 4 CEAM, Parque Tecnológico c/4 sector oeste, Paterna, 46980, Spain , Paterna
Type
Published Article
Journal
Biogeochemistry
Publisher
Springer-Verlag
Publication Date
Mar 01, 2000
Volume
48
Issue
3
Pages
261–281
Identifiers
DOI: 10.1023/A:1006289905991
Source
Springer Nature
Keywords
License
Yellow

Abstract

We studied the seasonality of total soil CO2efflux and labeled C-CO2 released from 14Clabeled straw incubated in the H horizon of asemi-arid Mediterranean forest soil. Fieldmeasurements were carried out over 520 days in aseries of reconstructed soil profiles with and withouta gravel layer below the H horizon. We monitored soilclimate and related this to soil CO2 efflux.Seasonal variations in soil CO2 efflux in asemiarid Mediterranean forest were mainly related tochanges in soil temperature. In spite of drought, highrespiration rates were observed in mid summer. Highsoil CO2 efflux in hot and dry episodes wasattributed to increases in soil biological activity.The minimum soil CO2 efflux occurred in latesummer also under dry conditions, probably related toa decrease in soil biological activity in deephorizons. Biological activity in organic layers waslimited by water potential (Ψ) in summer and bytemperature in winter. Rewetting a dry soil resultedin large increases in soil CO2 efflux only at hightemperatures. These large increases represented asignificant contribution to the decomposition oforganic matter in the uppermost horizons. Soilbiological activity in the uppermost horizons was moresensitive to changes in soil Ψ and hence tosummer rainstorms than the bulk soil microbialactivity. The presence of a layer of gravel improvedboth moisture and temperature conditions for thedecomposition of organic matter. As a result, soilCO2 efflux increased in soils containing rockfragments. These effects were especially large for theorganic layers.

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