Regular Article

Plant and Soil

, Volume 374, Issue 1, pp 883-898

Comparison of methane, nitrous oxide fluxes and CO2 respiration rates from a Mediterranean cork oak ecosystem and improved pasture

  • Alla ShvalevaAffiliated withInstituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa Email author 
  • , Filipe Costa e SilvaAffiliated withInstituto Superior de Agronomia, Universidade Técnica de Lisboa
  • , Joaquim Miguel CostaAffiliated withInstituto de Tecnologia Química e Biológica, Universidade Nova de LisboaInstituto Superior de Agronomia, Universidade Técnica de Lisboa
  • , Alexandra CorreiaAffiliated withInstituto Superior de Agronomia, Universidade Técnica de Lisboa
  • , Margaret AndersonAffiliated withCentre for Ecology and Hydrology, Natural Environment Research Council, Bush Estate
  • , Raquel Lobo-do-ValeAffiliated withInstituto Superior de Agronomia, Universidade Técnica de Lisboa
  • , David FangueiroAffiliated withInstituto Superior de Agronomia, Universidade Técnica de Lisboa
  • , Catarina BichoAffiliated withInstituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa
  • , João Santos PereiraAffiliated withInstituto Superior de Agronomia, Universidade Técnica de Lisboa
    • , Maria Manuela ChavesAffiliated withInstituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa
    • , Ute SkibaAffiliated withCentre for Ecology and Hydrology, Natural Environment Research Council, Bush Estate
    • , Cristina CruzAffiliated withFaculdade de Ciências, Universidade de Lisboa

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Abstract

Background and aims

During the recent decades, cork oak (Q. suber) mortality has been increasing in Mediterranean oak woodland endangering the economical and environmental sustainability of the “montado” ecosystem. This fact in combination with climate change and conversion of forestland to pasture may significantly affect the soil-atmosphere greenhouse gases (GHGs) exchange. Our study evaluates the impact of oak trees as compared to pasture on net ecosystem GHG (CH4, N2O, and CO2) exchange as well as the main environmental factors influencing this exchange.

Methods

We used field chamber measurements for the collection of GHGs under three different conditions: 1) open area (OA), 2) under tree canopy area (UC) and 3) improved pasture (IP). Experiments were done under typical Mediterranean climate at central Portugal in 2010 and 2011.

Results

The UC had higher nitrification potential, soil C/N ratio, electrical conductivity, litter input and soil organic matter (SOM) than OA and IP. SOM positively correlated with soil CH4 and N2O fluxes but not with soil CO2 respiration rates. Soil water content (SWC) drives both CH4 and N2O fluxes. Under certain conditions, when SWC reached a threshold (7 % for CH4 and 3 % for N2O) the result was net uptake and that net uptake increased with SWC. This was the case for the UC and OA. Conversely, for the IP soil water content above 4 % promoted net CH4 release.

Conclusions

Our results show that cork oak influences soil properties and consequently GHGs fluxes. In the UC the input of litter for SOM together with soil moisture, favoured microbiological activity and related GHGs fluxes. Soil temperature is a secondary factor in the studied conditions. Our results also emphasized the potential impact posed by decreased cork oak tree density in the functioning of the “montado” ecosystem.

Keywords

Evergreen oak Greenhouse gases Litter Mediterranean Organic matter Root density