NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Use of AIRSAR to identify woody shrub invasion and other indicators of desertification in the Jornada LTERThe replacement of semidesert grassland by woody shrubland is a widespread form of desertification. This change in physiognomy and species composition tends to sharply reduce the productivity of the land for grazing by domestic livestock, increase soil erosion and reduce soil fertility, and greatly alter many other aspects of ecosystem structure and functioning. Remote sensing methods are needed to assess and monitor shrubland encroachment. Detection of woody shrubs at low density would provide a particularly useful baseline on which to access changes, because an initially low shrub density often tends to increase even after cessation of the disturbance (e.g., overgrazing, drought, or fire suppression) responsible for triggering the initial stages of the invasion (Grover and Musick, 1990). Limited success has been achieved using optical remote sensing. In contrast to other forms of desertification, biomass does not consistently decrease with a shift from grassland to shrubland. Estimation of green vegetation amount (e.g., by NDVI) is thus of limited utility, unless the shrubs and herbaceous plants differ consistently in phenology and the area can be viewed during a season when only one of these is green. The objective of this study was to determine if the potential sensitivity of active microwave remote sensing to vegetation structure could be used to assess the degree of shrub invasion of grassland. Polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data were acquired for a semiarid site containing varied mixtures of shrubs and herbaceous vegetation and compared with ground observations of vegetation type and other landsurface characteristics. In this preliminary report we examine the response of radar backscatter intensity to shrub density. The response of other multipolarization parameters will be examined in future work.
Document ID
19950027389
Document Type
Conference Paper
Authors
Musick, H. Brad (New Mexico Univ. Albuquerque, NM, United States)
Schaber, Gerald G. (Geological Survey Flagstaff, AZ., United States)
Breed, Carol S. (Geological Survey Flagstaff, AZ., United States)
Date Acquired
September 6, 2013
Publication Date
January 23, 1995
Publication Information
Publication: JPL, Summaries of the Fifth Annual JPL Airborne Earth Science Workshop. Volume 3: AIRSAR Workshop
Subject Category
EARTH RESOURCES AND REMOTE SENSING
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Available Downloads

NameType 19950027389.pdf STI

Related Records

IDRelationTitle19950027368Analytic PrimarySummaries of the Fifth Annual JPL Airborne Earth Science Workshop. Volume 2: TIMS Workshop