A mobile tram system for systematic sampling of ecosystem optical properties

John A. Gamon, Yufu Cheng, Helen Claudio, Loren MacKinney, Daniel A. Sims

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


Reliable and repeatable field sampling methods are needed for monitoring ecosystem optical properties linked to carbon flux. Here we describe a tram system, consisting of a dual-detector spectrometer mounted on a robotic cart for mobile sampling of ecosystem spectral reflectance. To illustrate the application of this system for monitoring dynamic ecosystem activity, we illustrate how the tram can be used for exploring the multiple factors influencing the Normalized Difference Vegetation Index (NDVI), a measure of vegetation greenness and a key optical indicator of vegetation carbon dioxide assimilation. With this system, we collected five years of NDVI data for a chaparral ecosystem in Southern California subject to extreme disturbance. Key factors affecting NDVI at this site included snow cover, sky conditions (clear vs. cloudy), time of day, season, species composition, and environmental perturbations such as rainfall, drought and fire. Applications of this tram system include ecosystem monitoring, satellite validation, and developing surface-atmosphere flux models from remote sensing.

Original languageEnglish (US)
Pages (from-to)246-254
Number of pages9
JournalRemote Sensing of Environment
Issue number3
StatePublished - Aug 15 2006
Externally publishedYes


  • Chaparral
  • Disturbance
  • NDVI
  • Robotic tram system
  • SpecNet
  • Spectral reflectance

ASJC Scopus subject areas

  • Soil Science
  • Geology
  • Computers in Earth Sciences


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