DOI: 10.5061/dryad.f7m0cfxvm
title: Data from: Detecting seminal research contributions to the development of ethnobotany by reference publication year spectroscopy (RPYS)

description: This study aims to assess the growth in overall publication output in
 ethnobotany as well as provide a systematic examination of the history of
 ethnobotanical publications using reference publication year spectroscopy
 (RPYS). The study is based on 5201 papers published between 1974 and 2019
 covering 290006 non-distinct cited references (CRs), indexed in Science
 Citation Index-Expanded (SCI-Expanded) of Web of Science (WoS). The
 regression analysis indicated a compound annual growth rate of
 approximately 11% globally in ethnobotanical publications and the volume
 of publications doubles every approximately 6 years. The reference
 publication period was divided into four sub-periods in which a total of
 31 peaks are clearly identifiable, including five peaks from the first
 period (earliest to 1800), ten from the second (1801–1900), nine from the
 third (1901–1950) and seven from the last period (1951–2000). A total of
 44 publications were found to have been especially influential and
 landmark. Out of them, 31 (70%) were books and 11 (25%) were
 articles.  Out of the 11 articles, 5 (45%) were published in the
 same journal (Economic Botany). The first period had the lowest number of
 publications (5), including classic books like the Spanish translation of
 Dioscorides’ Materia Medica and Carolus Linnaeus’ Systema naturæ.
 Interestingly, about 30% of the studies that laid the foundation of
 ethnobotany and are discussed in this paper come from South Africa,
 pointing to the contribution of the African Continent to the foundation of
 the field of ethnobotany.
description: It is difficult to select all publications relating to a
 particular research area or study subject from a literature database as a
 source of information. To obtain a more exhaustive and inclusive
 publication data set, investigators applied four-step retrospective
 searching (Haunschild et al., 2016; Wang et al., 2014). This approach
 involves an initial search for key publications and a renewed search on
 the basis of the synonyms identified by the keyword analysis of these
 publications. This kind of approach is termed  “interactive query
 formulation” (Wacholder, 2011). In this study, investigators implemented
 an identical method for the data extraction. Investigators have used the
 WoS data (1974–2019) of the database producer Clarivate Analytics, derived
 from the Science Citation Index Expanded (SCI-E). The
 following four steps were used in this retrospective search
 method. 1. Investigators searched for the term
 <em>“Ethnobotany”</em> as topic in all four search domains of
 Web of Science (title, abstract, author keywords and Keyword Plus) for the
 publication years between 1974 and 2019. A publication set of 2729 papers
 was retrieved with this search strategy.  2. Bibexcel
 software (Persson et al. 2009) was used to extract all the author keywords
 of the publications (2729) for further analysis. All retrieved keywords
 were then selected and ranked by their frequency of occurrence.  The
 investigators looked for the ethnobotanical synonyms and identified the
 following ‘full list’ of keywords and their variants on consensus of all
 the authors of this paper, including Ethnobotany, ethno-botany,
 Ethno-medicinal plants, Ethnomedicinal plants, ethnobotanical,
 Ethno-botanical, Ethnobotanics, Folk medicinal plants, Traditional
 ethnobotanical knowledge, Traditional botanical knowledge, Traditional
 plant use, Medico-ethnobotany, Paleoethnobotany,
 Paleo-ethnobotany. 3. Investigators used a renewed
 topic search using the ‘full list’ of terms, with “OR” between all of
 them. The query was limited to the period 1974 to 2019 and finally
 resulted in 5201 publications. 4. Finally, the
 organization of literature and analysis was carried out. Investigators
 have processed the retrieved publications from aspects of overall growth.
 By following this method, an in-depth analysis of the referenced sources
 was carried out in all those publications that were retrieved.
 Investigators analysed ethnobotanical publications with respect
 to influential publications. To trace influential publications,
 investigators used a recently developed bibliometric method called
 “reference publication year spectroscopy” (RPYS) (Marx et al., 2014) in
 combination with a tool termed CRExplorer (http://
 www.crexplorer.net) (Thor et al., 2016). To analyse the cited
 references, the publication set is introduced to the CRExplorer and all
 CRs are mined. Equivalent references are then grouped and blended using
 the software’s clustering and merging facilities. References that appear
 less frequently than a certain limit are eliminated to decrease background
 noise and to enhance the corresponding spectrogram. Lastly, reference
 publication years are evaluated for frequently cited publications. Earlier
 RPYs involve a rather unique procedure, i.e. a relatively low cut-off of
 the minimum number of CRs, since the scale of the number of cited
 references (NCR, i.e., count of publications which cited a specific
 reference) differs significantly across different periods.
 To identify the landmark papers, investigators used an advanced
 indicator of the software called N_TOP10. This indicator helps to identify
 those publications which belong to the 10% most frequently cited
 publications over many citing publication years (Thor et al.,
 2018). The 5201 ethnobotanical publications included in
 this study contained 290006 non-distinct CRs. Managing (clustering,
 merging, and analysis) of a substantial volume of CRs is not an easy task.
 Hence, investigators divided the analysis into four time periods: (1) 1555
 to 1800, (2) 1801–1900, (3) 1901–1950 and (4) 1951–2000.
 Between 1555 and 1800 the highest peak in citations was 24,
 between 1801 and 1900 it was more than 28, between 1901 and 1950 it was
 more than 75, and lastly it increased to about 2200 during the last time
 period. The criterion for references to be excluded for the first three
 periods (i.e. 1555 (the earliest CRs) to 1800, 1801–1900 and 1901–1950) is
 1. For the fourth time period (1951–2000), investigators used a minimum of
 10 consistent with the study of (Haunschild et al., 2019a) after
 clustering and merging of reference variants.