Field validation of 1930s aerial photography: What are we missing?

D. M. Browning, Steve Archer, A. T. Byrne

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Aerial photography from the 1930s serves as the earliest synoptic depiction of vegetation cover. We generated a spatially explicit database of shrub (Prosopis velutina) stand structure within two 1.8 ha field plots established in 1932 to address two questions: (1) What are the detection limits of panchromatic 1936 aerial photography?, and (2) How do these influence P. velutina biomass estimates? Shrub polygons were manually digitized on 1936 imagery and linked to 1932 field measurements of P. velutina canopy area. Aboveground 1932 P. velutina biomass was estimated using a site-specific allometric relationship for field-measured canopy area. Shrub canopy detection limits on the 1936 imagery were comparable to those reported for contemporary imagery. Based on a conservative shrub size detection threshold of 3.8 m2, 5.8% of P. velutina biomass was missed. Spatial resolution (0.6 vs. 1.0 m) did not influence detection limits, but the overall accuracy of shrub cover estimates was greater on 1.0 m images. Presence of the sub-shrub Isocoma tenuisecta may also have significantly influenced estimates of P. velutina canopy area. These analyses illustrate the importance of standardizing aerial photo interpretation protocols, accounting for uncertainty estimating shrub biomass, and caution species-specific interpretations for historic aerial photography.

Original languageEnglish (US)
Pages (from-to)844-853
Number of pages10
JournalJournal of Arid Environments
Volume73
Issue number9
DOIs
StatePublished - Sep 2009

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Prosopis velutina
aerial photography
shrub
shrubs
detection limit
canopy
imagery
biomass
Isocoma
stand structure
polygon
vegetation cover
spatial resolution
uncertainty
detection

Keywords

  • Aboveground woody biomass
  • Detection limits
  • Error assessment
  • Historic aerial photography
  • Land cover
  • Panchromatic
  • Prosopis velutina
  • Retrospective ground truth
  • Retrospective mapping
  • Santa Rita experimental range
  • Sonoran Desert
  • Velvet mesquite

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes
  • Ecology

Cite this

Field validation of 1930s aerial photography : What are we missing? / Browning, D. M.; Archer, Steve; Byrne, A. T.

In: Journal of Arid Environments, Vol. 73, No. 9, 09.2009, p. 844-853.

Research output: Contribution to journalArticle

Browning, D. M. ; Archer, Steve ; Byrne, A. T. / Field validation of 1930s aerial photography : What are we missing?. In: Journal of Arid Environments. 2009 ; Vol. 73, No. 9. pp. 844-853.
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