Vascular plants mediate the effects of aridity and soil properties on ammonia-oxidizing bacteria and archaea

Manuel Delgado-Baquerizo*, Antonio Gallardo, Matthew D. Wallenstein, Fernando T. Maestre

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


An integrated perspective of the most important factors driving the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in natural ecosystems is lacking, especially in drylands. We evaluated how different climatic, abiotic, and nutrient-related factors determine AOA and AOB abundance in bare and vegetated microsites from grasslands throughout the Mediterranean Basin. We found a strong negative relationship between the abundance of AOA genes and soil fertility (availability of C, N, and P). Aridity and other abiotic factors (pH, sand content, and electrical conductivity) were more important than soil fertility in modulating the AOA/AOB ratio. AOB were more abundant under vegetated microsites, while AOA, highly resistant to stressful conditions, were more abundant in bare ground areas. These results suggest that AOA may carry out nitrification in less fertile microsites, while AOB predominate under more fertile conditions. Our results indicate that the influence of aridity and pH on the relative dominance of AOA and AOB genes is ultimately determined by local-scale environmental changes promoted by perennial vegetation. Thus, in spatially heterogeneous ecosystems such as drylands, there is a mutual exclusion and niche division between these microorganisms, suggesting that they may be functionally complementary.

Original languageEnglish (US)
Pages (from-to)273-282
Number of pages10
Issue number2
StatePublished - Aug 2013


  • Ammonium
  • AmoA genes
  • Aridity index
  • Organic C
  • PH

ASJC Scopus subject areas

  • Microbiology
  • Ecology
  • Applied Microbiology and Biotechnology


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