Alterations of nitrogen dynamics under elevated carbon dioxide in an intact Mojave Desert ecosystem: evidence from
S Billings1, S Schaeffer2, S Zitzer3
1Biological Sciences Department, University of Arkansas Fayetteville, Fayetteville, AR, 72701, USA. sbillin@mail.uark.edu.
Abstract:
We examined soil and vegetation N isotopic composition (δ15N) and soil inorganic N availability in an intact Mojave desert ecosystem to evaluate potential effects of elevated atmospheric CO2 on N cycling. Vegetation from the dominant perennial shrub Larrea tridentata under elevated CO2 was enriched in 15N. Over a 7-month sampling period, Larrea δ15N values increased from 5.7±0.1‰ to 9.0±1.1‰ with elevated CO2; under ambient conditions, δ15N values of shrubs increased from 4.9±0.3‰ to 6.6±0.7‰. No difference was found in soil δ15N under elevated and ambient CO2. Soil δ15N values under the drought deciduous shrubs Lycium spp. were greatest (7.2±0.3‰), and soil under the C4 perennial bunchgrass Pleuraphis rigida had the lowest values (4.5±0.2‰). Several mechanisms could explain the enrichment in 15N of vegetation with elevated CO2. Results suggest that microbial activity has increased with elevated CO2, enriching pools of plant-available N and decreasing N availability. This hypothesis is supported by a significant reduction of plant-available N under elevated CO2. This indicates that exposure to elevated CO2 has resulted in significant perturbations to the soil N cycle, and that plant δ15N may be a useful tool for interpreting changes in the N cycle in numerous ecosystems.
More Related Videos
10:19A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function
Published on: November 21, 2015
10:16Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling
Published on: January 16, 2014
Related Concept Videos
Inorganic Nitrogen Assimilation
The Nitrogen Cycle
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
Carbon-dioxide Fixation
Carbon-13 (¹³C) NMR: Overview
The Carbon Cycle
