Precipitation-sensitive dynamic threshold: A new and simple method to detect and monitor forest and woody vegetation cover in sub-humid to arid areas

Ron Drori*, Harel Dan, Michael Sprintsin, Efrat Sheffer

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

9 Scopus citations

Abstract

Remote-sensing tools and satellite data are often used to map and monitor changes in vegetation cover in forests and other perennial woody vegetation. Large-scale vegetation mapping from remote sensing is usually based on the classification of its spectral properties by means of spectral Vegetation Indices (VIs) and a set of rules that define the connection between them and vegetation cover. However, observations show that, across a gradient of precipitation, similar values of VI can be found for diαerent levels of vegetation cover as a result of concurrent changes in the leaf density (Leaf Area Index-LAI) of plant canopies. Here we examine the three-way link between precipitation, vegetation cover, and LAI, with a focus on the dry range of precipitation in semi-arid to dry sub-humid zones, and propose a new and simple approach to delineate woody vegetation in these regions. By showing that the range of values of Normalized Diαerence Vegetation Index (NDVI) that represent woody vegetation changes along a gradient of precipitation, we propose a data-based dynamic lower threshold of NDVI that can be used to delineate woody vegetation from non-vegetated areas. This lower threshold changes with mean annual precipitation, ranging from less than 0.1 in semi-arid areas, to over 0.25 in mesic Mediterranean area. Validation results show that this precipitation-sensitive dynamic threshold provides a more accurate delineation of forests and other woody vegetation across the precipitation gradient, compared to the traditional constant threshold approach.

Original languageAmerican English
Article number1231
JournalRemote Sensing
Volume12
Issue number8
DOIs
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2020 by the authors.

Keywords

  • Leaf area index
  • NDVI
  • Precipitation gradient
  • Rainfall
  • SENTINEL II
  • Semi-arid

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