Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/22748
Title: Testing methods for challenging the National Wetland Plant List : using Tsuga canadensis (L.) Carr. (Eastern Hemlock) as a case study
Authors: Lichvar, Robert.
Goulet, Jennifer J.
Keywords: Indicator status
National Wetland Plant List
Plants--Classification
Vegetation--Sampling
Vegetation surveys
Wetland ecology
Wetland frequency
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: ERDC/CRREL;TR-17-9
Abstract: Abstract: This study explored methods for collecting and analyzing data during challenges to wetland ratings on the National Wetland Plant List (NWPL) to determine if study area size and landscape type affect wetland frequency and ratings. Data were collected in three different-sized study areas with different types of landscapes. Wetland frequency was calculated by using the original and an adjusted formula; and wetland ratings were predicted by using a Bayesian model. The original formula produced fewer hydrophytic ratings than the adjusted formula and the Bayesian model. In the smallest study areas (100 km²), wetland ratings varied with landscape characteristics. The same wetland frequencies and ratings were produced in moderately large (20,000 km²) and large (742,800 km²) study areas provided sample size was adequate. These results suggest that a wetland determination should be made for each sample unit based on the presence or absence of wetland indicators. Sample size should be large enough to achieve a confidence interval of 95% and a 3%–5% margin of error. When wetland frequency is close to 33%, Bayesian models could provide support for wetland rating determinations. The National Technical Committee for Wetland Vegetation and the National Panel of the NWPL will work with challengers to create a study design appropriate for each species.
URI: http://hdl.handle.net/11681/22748
http://dx.doi.org/10.21079/11681/22748
Appears in Collections:Technical Report

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