Ecosystem response to nutrient enrichment across an urban airshed in the Sonoran Desert

Sharon Hall, Ryan A. Sponseller, Nancy Grimm, David Huber, Jason P. Kaye, Christopher Clark, Scott L. Collins

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Rates of nitrogen (N) deposition have increased in arid and semiarid ecosystems, but few studies have examined the impacts of long-term N enrichment on ecological processes in deserts. We conducted a multiyear, nutrient-addition study within 15 Sonoran Desert sites across the rapidly growing metropolitan area of Phoenix, Arizona (USA). We hypothesized that desert plants and soils would be sensitive to N enrichment, but that these effects would vary among functional groups that differ in terms of physiological responsiveness, proximity to surface N sources, and magnitude of carbon (C) or water limitation. Inorganic N additions augmented net potential nitrification in soils, moreso than net potential N mineralization, highlighting the important role of nitrifying microorganisms in the nitrate economy of drylands. Winter annual plants were also responsive to nutrient additions, exhibiting a climate-driven cascade of resource limitation, from little to no production in seasons of low rainfall (winter 2006 and 2007), to moderate N limitation with average precipitation (winter 2009), to limitation by both N and P in a season of above-normal rainfall (winter 2008). Herbaceous production is a potentially important mechanism of N retention in arid ecosystems, capable of immobilizing an amount equal to or greater than that deposited annually to soils in this urban airshed. However, interannual variability in precipitation and abiotic processes that limit the incorporation of detrital organic matter into soil pools may limit this role over the long term. In contrast, despite large experimental additions of N and P over four years, growth of Larrea tridentata, the dominant perennial plant of the Sonoran Desert, was unresponsive to nutrient enrichment, even during wet years. Finally, there did not appear to be strong ecological interactions between nutrient addition and location relative to the city, despite the nearby activity of nearly four million people, perhaps due to loss or transfer pathways that limit long-term N enrichment of ecosystems by the urban atmosphere.

Original languageEnglish (US)
Pages (from-to)640-660
Number of pages21
JournalEcological Applications
Volume21
Issue number3
DOIs
StatePublished - Apr 2011

Fingerprint

ecosystem response
nutrient enrichment
desert
winter
nutrient
ecosystem
soil
urban atmosphere
rainfall
perennial plant
annual plant
metropolitan area
functional group
nitrification
microorganism
mineralization
nitrate
organic matter
nitrogen
carbon

Keywords

  • Ambrosia
  • Arid ecosystem
  • Arizona
  • Larrea tridentate
  • N deposition
  • Nitrogen fertilization
  • Pectocarya spp.
  • Phosphorus
  • Sonoran Desert
  • Urban environments
  • USA
  • Winter ephemeral annual plants

ASJC Scopus subject areas

  • Ecology

Cite this

Ecosystem response to nutrient enrichment across an urban airshed in the Sonoran Desert. / Hall, Sharon; Sponseller, Ryan A.; Grimm, Nancy; Huber, David; Kaye, Jason P.; Clark, Christopher; Collins, Scott L.

In: Ecological Applications, Vol. 21, No. 3, 04.2011, p. 640-660.

Research output: Contribution to journalArticle

Hall, Sharon ; Sponseller, Ryan A. ; Grimm, Nancy ; Huber, David ; Kaye, Jason P. ; Clark, Christopher ; Collins, Scott L. / Ecosystem response to nutrient enrichment across an urban airshed in the Sonoran Desert. In: Ecological Applications. 2011 ; Vol. 21, No. 3. pp. 640-660.
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