Biocrusts control the nitrogen dynamics and microbial functional diversity of semi-arid soils in response to nutrient additions

Manuel Delgado-Baquerizo*, Lourdes Morillas, Fernando T. Maestre, Antonio Gallardo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

Aims: Human activities are causing imbalances in the nutrient cycles in natural ecosystems. However, we have limited knowledge of how these changes will affect the soil microbial functional diversity and the nitrogen (N) cycle in drylands, the biggest biome on Earth. Communities dominated by lichens, mosses and cyanobacteria (biocrusts) influence multiple processes from the N cycle such as N fixation and mineralization rates. We evaluated how biocrusts modulate the effects of different N, carbon (C) and phosphorus (P) additions on theN availability, the dominance of different available N forms and the microbial functional diversity in dryland soils. Methods: Soil samples from bare ground (BG) and biocrust-dominated areas were gathered from the center of Spain and incubated during seven or 21 days under different combinations of N, C and P additions (N, C, P, N + C, N + P, P + C, and C + N + P). Results: The relative dominance of dissolved organic N (DON) and the microbial functional diversity were higher in biocrust than in BG microsites when C or P were added. Changes in the C to N ratio, more than N availability, seem to modulate N transformation processes in the soils studied. In general, biocrusts increased the resilience to N impacts (N, C + N, N + P, C + N + P) of the total available N, ammonium, nitrate and DON when C was present. Conclusions: Our results suggest that biocrusts may buffer the effects of changes in nutrient ratios on microbial functional diversity and DON dominance in dryland soils. Thus, these organisms may have an important role in increasing the resilience of the N cycle to imbalances in C, N and P derived from human activities.

Original languageEnglish (US)
Pages (from-to)643-654
Number of pages12
JournalPLANT AND SOIL
Volume372
Issue number1-2
DOIs
StatePublished - Nov 2013

Keywords

  • Carbon
  • Dissolved organic N
  • Mineralization
  • Phosphorus
  • Shannon-Weaver diversity index

ASJC Scopus subject areas

  • Soil Science
  • Plant Science

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