Responses of soil microorganisms to resource availability in urban, desert soils

Michelle L. McCrackin, Tamara K. Harms, Nancy Grimm, Sharon Hall, Jason P. Kaye

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Terrestrial desert ecosystems are strongly structured by the distribution of plants, which concentrate resources and create islands of fertility relative to interplant spaces. Atmospheric nitrogen (N) deposition resulting from urbanization has the potential to change those spatial patterns via resource inputs, resulting in more homogeneous soil resource availability. We sampled soils at 12 desert remnant sites around Phoenix, Arizona along a model-predicted gradient in N deposition to determine the degree to which deposition has altered spatial patterns in soil resource availability and microbial activity. Soil microbial biomass and abundance were not influenced by atmospheric N deposition. Instead, plant islands remained strong organizers of soil microbial processes. These islands of fertility exhibited elevated pools of resources, microbial abundance, and activity relative to interspaces. In both plant islands and interspaces, soil moisture and soil N concentrations predicted microbial biomass and abundance. Following experimental wetting, carbon dioxide (CO 2) flux from soil of interspaces was positively correlated with N deposition, whereas in plant islands, soil CO2 flux was positively correlated with soil moisture content and soil organic matter. Soil CO 2 flux in both patch types showed rapid and short-lived responses to precipitation, demonstrating the brief time scales during which soil biota may process deposited materials. Although we observed patterns consistent with N limitation of microbes in interspaces, we conclude that atmospheric N deposition likely accumulates in soils because microbes are primarily limited by water and secondarily by carbon or nitrogen. Soil microbial uptake of atmospherically deposited N likely occurs only during sparse and infrequent rainfall.

Original languageEnglish (US)
Pages (from-to)143-155
Number of pages13
JournalBiogeochemistry
Volume87
Issue number2
DOIs
StatePublished - Feb 2008

Fingerprint

desert soil
soil microorganism
resource availability
Microorganisms
Availability
Soils
soil
fertility
desert
soil moisture
Soil moisture
Carbon Monoxide
Fluxes
soil biota
nitrogen
Biomass
Nitrogen
biomass
resource
wetting

Keywords

  • Atmospheric nitrogen deposition
  • Islands of fertility
  • Phoenix, AZ
  • Soil microbes
  • Soil respiration
  • Sonoran Desert

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Environmental Science(all)

Cite this

Responses of soil microorganisms to resource availability in urban, desert soils. / McCrackin, Michelle L.; Harms, Tamara K.; Grimm, Nancy; Hall, Sharon; Kaye, Jason P.

In: Biogeochemistry, Vol. 87, No. 2, 02.2008, p. 143-155.

Research output: Contribution to journalArticle

McCrackin, Michelle L. ; Harms, Tamara K. ; Grimm, Nancy ; Hall, Sharon ; Kaye, Jason P. / Responses of soil microorganisms to resource availability in urban, desert soils. In: Biogeochemistry. 2008 ; Vol. 87, No. 2. pp. 143-155.
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