Decadal-scale aspen changes: Evidence in remote sensing and tree ring data

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Question: (1) Which remote sensing classification most successfully identify aspen using multitemporal Landsat 5 TM images and airborne lidar data? (2) How has aspen distribution changed in southwestern Idaho? (3) Are topographic variables and conifer encroachment correlated with aspen changes? Location: Reynolds Creek Experimental Watershed in southwestern Idaho, USA. Methods: Multi-temporal Landsat 5 TM and lidar data were used individually and fused together. The best classification model was compared with a 1965 aspen map and tree ring data. Conifer encroachment was examined via image-based change detection and field mapping. Lidar-derived topographic variables were correlated with aspen change patterns using quantile regression models. Results: The best Landsat 5 TM classification was a normalized difference vegetation index (NDVI)-based approach with 92% overall accuracy. The lidar classification of tree presence/absence performed with 100% overall accuracy. Fusing the lidar classification with various Landsat 5 TM classifications improved overall accuracies 3 to 6%. Among the fusion models, the NDVI-lidar fusion performed best with 96% overall accuracy. Change detection indicated 69% decline in aspen cover, but 179% increase in aspen cover in other areas of the watershed. Conifers have completely replaced 17% of the aspen, while 93% of the remaining aspen stands have young Douglas-fir and western juniper trees underneath the aspen canopy. Aspen significantly decreased (P-values <0.05) with increasing elevation (up to 2150m) and decreasing slope. Conclusions: Landsat 5 TM data used with a NDVI-based approach provide an accurate method to classify aspen distribution. Landsat 5 TM classifications can be further improved via fusion with lidar data. Aspen change patterns are spatially variable: while aspen is drastically declining in some parts of this watershed, aspen is increasing in other areas.

Original languageEnglish (US)
Pages (from-to)no
JournalApplied Vegetation Science
Issue number1
StatePublished - Feb 2012
Externally publishedYes


  • Active sensors
  • Aspen decline
  • Fusion
  • Laser data
  • Vegetation height

ASJC Scopus subject areas

  • Ecology
  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law


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