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Effects of dry-rewetting events on soil respiration in a Mediterranean pine forest
Year:2015
Research Areas
  • Agriculture
Information
Abstract
Mediterranean climate is characterized by dry summers followed by heavy rainfalls leading to soil drying-rewetting (DRW) cycles, resulting in a sharp increase of soil respiration (Rs) rates and soil activity observed after rewetting is usually higher than at soils undergoing constant moist conditions. It is not clear whether the mechanism responsible for the soil CO2 pulse after rewetting is the use of dead microbial cells and osmolytes by surviving microbes, or the increase of substrate availability due to physical breakdown of the aggregates. This work aimed at quantifying the aggregate size effect on Rs pulses due to DRW in Scots pine forests. Further, we looked at the CO2 pulses after rewetting as affected by the age and structure of the forest stand. Composite soil samples from a young-dense and a mature-open Scots pine forest stand in Sierra de Guadarrama were collected at 0-15 and 15-30 cm depth. Aggregate size-classes were obtained by sieving - 2-6 mm and <2mm - and incubated under environmental controlled conditions. Rs rates were measured periodically by NaOH trapping. The incubation comprised 240 days under constant conditions, followed by a DRW cycle for 40 additional days. Cumulative soil CO2 fluxes were high and not significantly different between stands (5.1 ± 1.3 and 5.7 ± 0.6 Mg CO2-C ha-1 in the young and the mature stands, respectively). Decomposability (i.e. CO2 emitted by unit of C) was not affected by aggregate size, indicating that both aggregate sizes are prone to mineralization pulses after soil DRW. Soils from the mature stand reacted more markedly to the DRW cycles: 11.4 ± 2.8% of the C emitted was produced after the DRW, while in the young stand only 5.3±0.5% of the C was due to the DRW. This indicates that the forest structure may have a role in the availability of substrate for soil microorganisms. The larger response of mature stand soils to DRW events may lead to higher emissions if the frequency of DRW events increases in the future.
International
No
Congress
REMEDIA IV Workshop sobre Mitigación de gases de efecto invernadero provenientes del sector agroforestal
960
Place
Madrid
Reviewers
Si
ISBN/ISSN
978-84-606-6727-8
Start Date
23/04/2015
End Date
25/04/2015
From page
13
To page
13
Libro de Abstracts REMEDIA IV Workshop
Participants
  • Autor: Carlos Ortiz Oñate (UPM)
  • Autor: Eugenio Díaz-Pinés
  • Autor: Agustin Rubio Sanchez (UPM)
Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Calidad de Suelos y Aplicaciones medioambientales
  • Departamento: Sistemas y Recursos Naturales
  • Departamento: Producción Agraria
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