The total diversity of all organisms and ecosystems at various spatial scales (from genes to entire biomes).
"Appendix I: Glossary". IPCC Fourth Assessment Report. 2007. http://www.ipcc.ch/pdf/glossary/ar4-wg2.pdf
The variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.
Terms and Definitions - FRA 2015, Forest Resources Assessment Working Paper 180, FAO, 2015 (http://www.fao.org/docrep/017/ap862e/ap862e00.pdf).