Plant biodiversity data and associated soils, ecological site, and livestock management data that were collected at the USDA-ARS Northern Great Plains Research Laboratory in 2011 and 2013. Data were collected using the modified Whittaker technique. The unique design of the Whitaker method reduces autocorrelation among subplots, which is common in standard transect methods (Goslee, 2006). Grassland scientists worldwide use this standard technique to quantify and monitor plant diversity on, for example, Serengeti grasslands (Anderson et al., 2006), South African serpentine grasslands (Reddy et al., 2009), and rangelands in Turkey (Firinciglu et al., 2007) among many other environments. In addition, Sanderson at the NGPRL and Goslee at ARS University Park have developed a large database on plant species diversity of grazing lands in the U.S. (nearly 300 sites sampled using the Whitaker plot method). The use of the standardized Whitaker plot method allows us to combine data from the northern Great Plains with other databases worldwide for larger-scale meta-analyses. The multiscale technique also enables comparison of vegetation dynamics at multiple scales. Resources in this dataset: Resource Title: NGPRL modified Whittaker data File Name: NGPRL_ModWhit.csv Resource Title: Ancillary data for NGPRL modified Whittaker plots File Name: NGPRL_ModWhit_Ancillary data.csv Resource Title: Data dictionary for NGPRL modified Whittaker data File Name: Modified Whittaker dataset dictionary.csv Methods for NGPRL modified Whittaker data File Name: modWhit methods and metadata.docx This record was taken from the USDA Enterprise Data Inventory that feeds into the https://data.gov catalog. Data for this record includes the following resources: • https://data.nal.usda.gov/system/files/NGPRL_ModWhit.csv • https://data.nal.usda.gov/system/files/NGPRL_ModWhit_Ancillary%20data.csv • https://data.nal.usda.gov/system/files/Modified%20Whittaker%20dataset%20dictionary.csv • https://data.nal.usda.gov/system/files/modWhit%20methods%20and%20metadata.docx For complete information, please visit https://data.gov.