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Inter-Observer Error in Wetland Vegetation Surveys

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Abstract

Vegetation surveys are a common component of sampling wetlands. Although observer error is known to be ubiquitous in vegetation sampling in general, extremely few studies of observer error have been conducted in wetland habitats. We quantified inter-observer error in sampling emergent, scrub-shrub, and forested wetlands located in Ohio. Two expert observers independently recorded species present and estimated foliar cover within ten cover classes in 10 × 10 m modules, which were units of larger sample plots, in six wetlands. Although the numbers of species recorded by observers were similar, the identities of species recorded differed due to overlooking of species actually present, misidentification error, and not recording species to the same taxonomic level. We calculated rates of pseudoturnover due to each of these three sources of error at different spatial scales (i.e., plot vs. module level), for different vegetation strata (i.e., herbaceous vs. woody) and for the three vegetation types. We also quantified estimation error associated with cover class estimates. Several different types of VIBIs (Vegetation Index of Biotic Integrity) were calculated based on each observer’s records. Pseudoturnover rates ranged from 15 to 40%, and observers recorded different cover classes 59% of the time. VIBI categorization was affected 17% of the time.

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Acknowledgements

Doug Marcum provided field assistance. EnviroScience Inc., Stow OH, contributed valuable information to this project. Rob Curtis (Summit Metro Parks) and Jon Reinier (Cleveland Metro Parks) assisted with voucher verification. 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.

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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 & Craig C. Young

  3. National Park Service, Heartland Inventory and Monitoring Program, Cuyahoga Valley National Park, 15610 Vaughn Road, Brecksville, OH, 44141, USA

    Sonia N. Bingham

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  1. Lloyd W. Morrison
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  2. Sonia N. Bingham
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Correspondence to Lloyd W. Morrison.

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Morrison, L.W., Bingham, S.N. & Young, C.C. Inter-Observer Error in Wetland Vegetation Surveys. Wetlands 40, 249–258 (2020). https://doi.org/10.1007/s13157-019-01173-8

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