Title : 
 Data : Nematode - based indices in soil ecology - application , utility and future directions 

 Abstract : 
 The underlying data sets contain references from a literature survey that was undertaken using the Web of Science Core Collection database . The data set ( Du_Perez_etal_2021_references.ris ) contains all references ( 672 ) that were used to create the figures in the corresponding paper with the focus on nematode - based bioindicators ( NBIs ) . The data set ( Du_Perez_et_al_2021.xlsx ) contains all references added by information about NBIs , location information , spatial scale , land use , land cover and study focus which are explained below . We identified three scientific papers , namely Bongers ( 1990 ) , Ferris et al . ( 2001 ) , and Ferris ( 2010 ) , that serve as the foundation and main reference works for scientists and researchers that report on the application of NBIs . In total , 11 NBIs were used in these studies , namely Maturity Index , Maturity Index 2 - 5 , Plant - parasitic Index , Sigma maturity index , Colonizer - Persister ( CP ) -Triangle , Enrichment Index , Structure Index , Basal Index , Channel Index , Food Web Analysis , and Metabolic footprints . Using the Cited Reference Search tool , a search was conducted for works ( up until the end of 2020 ; last search performed 31 March 2021 ) that cited each of the above - mentioned scientific papers . This returned 1 113 , 653 , and 122 citations , respectively , for the Bongers ( 1990 ) , Ferris et al . ( 2001 ) , and Ferris ( 2010 ) papers . The results were combined , duplicates removed , and further refined to include only peer - reviewed scientific articles . Furthermore , all marine and freshwater studies were excluded . Finally , a total of 1199 papers was included in the analyses . 
  The next step was to screen each paper to assess whether it met the following basic criteria : 1 ) empirical study ( therefore not a review or meta - analysis ) , 2 ) application of at least one NBI , and 3 ) focused on terrestrial habitat(s ) . A total of 672 scientific papers met these criteria and , from them , the following information was extracted and recorded : i ) which NBIs were applied , ii ) location information and spatial scale of the study site(s ) , iii ) study focus , and iv ) land use and land cover information . 
  The study foci were identified based on the knowledge and experience of the authors . The land use and land cover criteria , in turn , were based on SEEA ( 2012 ) , which defines land use as ‘ the activities undertaken and the institutional arrangements put in place for a given area for the purposes of economic production , or the maintenance and restoration of environmental functions ’ . Land use therefore classifies all areas under human management according to its use into five categories namely : ‘ forestry ’ , ‘ not in use ’ , ‘ agriculture ’ , ‘ built - up and related ’ , and ‘ maintenance and restoration ’ . Land cover , in turn , is defined by   as ‘ the observed physical and biological cover of the Earth ’s surface and includes natural vegetation and abiotic ( non - living ) surfaces ’ . Six land cover categories were recognized , namely ‘ sparse ’ , ‘ grassland ’ , ‘ tree - covered ’ , ‘ shrub - covered ’ , ‘ herbaceous crops ’ , and ‘ woody and multi crop ’ . The ‘ sparse ’ category represents both barren terrestrial land and sparsely vegetated land . Further information on each land use and land cover category is provided in the section 3.3 . The above mentioned references are as follows : Bongers , T. , 1990 . The maturity index : an ecological measure of environmental disturbance based on nematode species composition . Oecologia 83 , 14 - 19 . and Ferris , H. , 2010 . Form and function : metabolic footprints of nematodes in the soil food web . European Journal of Soil Biology 46 , 97 - 104 . and Ferris , H. , Bongers , T. , De Goede , R.G.M. , 2001 . A framework for soil food web diagnostics : extension of the nematode faunal analysis concept . Applied Soil Ecology 18 , 13 - 29 . and SEEA , 2012 . System of Environmental - Economic Accounting — Central Framework . United Nations , European Union , Food and Agriculture Organization of the United Nations , International Monetary Fund , Organisation for Economic Co - operation and Development , The World Bank , p. 346 .