Species functional redundancy, random extinctions and the stability of ecosystems

Citation
Cr. Fonseca et G. Ganade, Species functional redundancy, random extinctions and the stability of ecosystems, J ECOLOGY, 89(1), 2001, pp. 118-125
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF ECOLOGY
ISSN journal
0022-0477 → ACNP
Volume
89
Issue
1
Year of publication
2001
Pages
118 - 125
Database
ISI
SICI code
0022-0477(200102)89:1<118:SFRREA>2.0.ZU;2-2
Abstract
1 The level of functional redundancy in natural communities is likely to mo dulate how ecosystem stability is affected by local species extinction. Thu s, extinction should have no effect if all species have similar functions b ut a major effect if each carries different functions 2 We provide a probabilistic framework that, from any distribution of speci es number across functional groups, generates specific predictions of how f unctional groups are lost when species become randomly extinct within a giv en community. In particular, we predict how many species can go extinct bef ore a community loses its first functional group, a useful index for conser vation purposes. 3 We demonstrate that the probability of a whole functional group becoming extinct from a given community increases with the number of recognized func tional groups (functional richness) but decreases with species richness and functional evenness (the distribution of species across functional groups) . 4 Application of this framework to one published data set for a South Ameri can plant community suggested that, if local extinction is random, 75% of t he species could be lost before the disappearance of the first functional g roup. 5 However. if redundancy is to be used to determine conservation priorities , the definition of functional groups must be carefully reviewed.