Divergent responses of vegetation cover in Southwestern US ecosystems to dry and wet years at different elevations

Stefanie M. Herrmann, Kamel Didan, Armando Barreto-Munoz, Michael A. Crimmins

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


In the semiarid Southwestern United States, prolonged drought conditions since the early 2000s have resulted in widespread declines of the vegetation productivity in this water-constrained ecosystem, as revealed by analyses of the Normalized Difference Vegetation Index (NDVI). However, the spatial pattern of the NDVI response to dry years is not uniform: a divergent response of NDVI to precipitation is observed between the low-lying desert and the high montane forests at elevations above 2,500 meter. We analyzed relationships between 15 years of Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI and gridded climate data (PRISM) along elevation gradients at scales from regional to local. Our elevation-explicit analysis captures the transition from water-limited to temperature-limited ecosystems, with a sign-reversal in the correlation coefficient between precipitation and NDVI observed at about 2,500-3,000m altitude. We suggest warmer temperatures and less snow cover associated with drier years as explanations for high elevation gains in vegetation productivity during dry years.

Original languageEnglish (US)
Article number124005
JournalEnvironmental Research Letters
Issue number12
StatePublished - Nov 24 2016


  • NDVI
  • US Southwest
  • climate dynamics
  • drought
  • elevation gradient
  • vegetation productivity

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Environmental Science
  • Public Health, Environmental and Occupational Health


Dive into the research topics of 'Divergent responses of vegetation cover in Southwestern US ecosystems to dry and wet years at different elevations'. Together they form a unique fingerprint.

Cite this