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1 May 2011 Comparison of Point Intercept and Image Analysis for Monitoring Rangeland Transects
J Cagney, S. E Cox, D. T Booth
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Abstract

There is global recognition that sustainable land use requires monitoring that will detect change on a scale that protects the resource. That fundamental necessity is threatened where labor-intensive methods and high labor costs cause sampling deficiencies and increased Type-II error rates (false negatives). Ground-based imaging is a monitoring method that reduces monitoring labor costs. Nadir (vertical) images acquired with common digital cameras can be manually analyzed for cover using free software. We used an innovative field protocol to acquire standardized, freehand, nadir images (samples) of rangeland, then compared point intercept (PI) and image-analysis techniques. Between methods, precision (repeatability) across users was equivalent; cover measurements were often different, and the image-analysis technique took only a third as long to complete. Image analysis has several advantages over PI besides the reduced labor cost: Images are permanent resource records available for reanalysis if data are questioned, if software improves, or if management objectives change; and image analysis is less biased by moving vegetation, moving pointing devices, and bright vegetation color.

Society for Range Management
J Cagney, S. E Cox, and D. T Booth "Comparison of Point Intercept and Image Analysis for Monitoring Rangeland Transects," Rangeland Ecology and Management 64(3), 309-315, (1 May 2011). https://doi.org/10.2111/REM-D-10-00090.1
Published: 1 May 2011
JOURNAL ARTICLE
7 PAGES


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KEYWORDS
cover measurement
land management
SamplePoint
Type-II error risk
Vegetation sampling
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