The Grass Is Not Always Greener on the Other Side: Seasonal Reversal of Vegetation Greenness in Aspect-Driven Semiarid Ecosystems

Nikul Kumari, Patricia M. Saco, Jose F. Rodriguez, Samuel A. Johnstone, Ankur Srivastava, Kwok Pan CHUN, Omer Yetemen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Our current understanding of semiarid ecosystems is that they tend to display higher vegetation greenness on polar-facing slopes (PFS) than on equatorial-facing slopes (EFS). However, recent studies have argued that higher vegetation greenness can occur on EFS during part of the year. To assess whether this seasonal reversal of aspect-driven vegetation is a common occurrence, we conducted a global-scale analysis of vegetation greenness on a monthly time scale over an 18-year period (2000–2017). We examined the influence of climate seasonality on the normalized difference vegetation index (NDVI) values of PFS and EFS at 60 different catchments with aspect-controlled vegetation located across all continents except Antarctica. Our results show that an overwhelming majority of sites (70%) display seasonal reversal, associated with transitions from water-limited to energy-limited conditions during wet winters. These findings highlight the need to consider seasonal variations of aspect-driven vegetation patterns in ecohydrology, geomorphology, and Earth system models.

Original languageEnglish
Article numbere2020GL088918
JournalGeophysical Research Letters
Volume47
Issue number15
DOIs
Publication statusPublished - 16 Aug 2020

Scopus Subject Areas

  • Geophysics
  • Earth and Planetary Sciences(all)

User-Defined Keywords

  • ecosystem
  • hillslope aspect
  • NDVI
  • remote sensing
  • semiarid
  • vegetation greenness

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