title: High plant diversity is needed to maintain ecosystem services.
abstract: Biodiversity is rapidly declining worldwide, and there is consensus that this can decrease ecosystem functioning and services. It remains unclear, though, whether few or many of the species in an ecosystem are needed to sustain the provisioning of ecosystem services. It has been hypothesized that most species would promote ecosystem services if many times, places, functions and environmental changes were considered; however, no previous study has considered all of these factors together. Here we show that 84% of the 147 grassland plant species studied in 17 biodiversity experiments promoted ecosystem functioning at least once. Different species promoted ecosystem functioning during different years, at different places, for different functions and under different environmental change scenarios. Furthermore, the species needed to provide one function during multiple years were not the same as those needed to provide multiple functions within one year. Our results indicate that even more species will be needed to maintain ecosystem functioning and services than previously suggested by studies that have either (1) considered only the number of species needed to promote one function under one set of environmental conditions, or (2) separately considered the importance of biodiversity for providing ecosystem functioning across multiple years, places, functions or environmental change scenarios. Therefore, although species may appear functionally redundant when one function is considered under one set of environmental conditions, many species are needed to maintain multiple functions at multiple times and places in a changing world.
authors.affiliation: Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada. forest.isbell@gmail.com
authors.forename: Forest
authors.initials: F
authors.lastname: Isbell
authors.forename: Vincent
authors.initials: V
authors.lastname: Calcagno
authors.forename: Andy
authors.initials: A
authors.lastname: Hector
authors.forename: John
authors.initials: J
authors.lastname: Connolly
authors.forename: W Stanley
authors.initials: WS
authors.lastname: Harpole
authors.forename: Peter B
authors.initials: PB
authors.lastname: Reich
authors.forename: Michael
authors.initials: M
authors.lastname: Scherer-Lorenzen
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmid
authors.forename: David
authors.initials: D
authors.lastname: Tilman
authors.forename: Jasper
authors.initials: J
authors.lastname: van Ruijven
authors.forename: Alexandra
authors.initials: A
authors.lastname: Weigelt
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Wilsey
authors.forename: Erika S
authors.initials: ES
authors.lastname: Zavaleta
authors.forename: Michel
authors.initials: M
authors.lastname: Loreau
mesh_terms: D044822:Biodiversity; D004463:Ecology / Q000379:methods; D017753:Ecosystem; D053476:Extinction, Biological; D008954:Models, Biological; D063245:Plant Development; D018521:Plant Physiological Phenomena; D010944:Plants / Q000145:classification; D006109:Poaceae; D013045:Species Specificity