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Nonsampling error in vegetation surveys: understanding error types and recommendations for reducing their occurrence

Plant Ecology volume 222, pages 577–586 (2021)Cite this article

Abstract

Observer error is ubiquitous in vegetation sampling. Observer error, along with other types of related nonsampling error, may result in species richness being artificially underestimated (i.e., false-negative errors) or artificially overestimated (i.e., false-positive errors). Because of the manner in which observer error is usually quantified, there exists a strong bias against the discovery of false positives. At least seven different types of nonsampling errors can occur when surveying vegetation species composition: overlooking, misidentification, cautious, mythical, anecdotal, transcription, and relocation. Six of these error types can result in false negatives and five can result in false positives. Another type of observer error that can occur in plant surveys is estimation error, which occurs when abundances are not accurately estimated. There are many potential underlying causes of nonsampling error. Humans observers, even when highly trained and experienced, are prone to commit errors through slips, lapses, and mistakes. A number of contributing factors of observer error have been identified, including characteristics associated with the vegetation, the environment, and the observers themselves; design-based flaws may also occur. Although it may not be possible to eliminate all sources of nonsampling error, most can be reduced through understanding the mechanisms underlying the various types of error, followed by training exercises and the consistent use of appropriate operating procedures.

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Acknowledgements

M. DeBacker and S. Leis provided helpful comments on a previous version of this manuscript. The ideas presented benefitted from discussions on field sampling techniques and issues with S. Leis, M. DeBacker, C. Young, and S. Bingham. Views, statements, findings, conclusions, recommendations, and data in this report are those of the author(s) and do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the National Park Service.

Funding

This work was funded by the Inventory and Monitoring Program of the National Park Service.

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Authors and Affiliations

  1. Department of Biology, Missouri State University, 901 S. National Avenue, Springfield, MO, 65897, USA

    Lloyd W. Morrison

  2. National Park Service, Heartland Inventory and Monitoring Program, Wilson’s Creek National Battlefield, 6424 W. Farm Road 182, Republic, MO, 65738, USA

    Lloyd W. Morrison

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  1. Lloyd W. Morrison
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Correspondence to Lloyd W. Morrison.

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Morrison, L.W. Nonsampling error in vegetation surveys: understanding error types and recommendations for reducing their occurrence. Plant Ecol 222, 577–586 (2021). https://doi.org/10.1007/s11258-021-01125-5

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Keywords

  • Cautious error
  • Misidentification error
  • Mythical error
  • Nonsampling error
  • Observer error
  • Overlooking error