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Diversity decreases invasion via both sampling and complementarity effects
Author(s) -
Fargione Joseph E.,
Tilman David
Publication year - 2005
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/j.1461-0248.2005.00753.x
Subject(s) - species richness , biology , ecology , monoculture , biomass (ecology) , complementarity (molecular biology) , invasive species , resistance (ecology) , competition (biology) , ecosystem , genetics
Complementarity and sampling effects may both contribute to increased invasion resistance at higher diversity. We measured plant invader biomass across a long‐term experimental plant diversity gradient. Invader species’ biomass was inhibited in more diverse plots, largely because of the presence of strongly competitive C 4 bunchgrasses, consistent with a sampling effect. Invader biomass was negatively correlated with resident root biomass, and positively correlated with soil nitrate concentrations, suggesting that competition for nitrogen limited invader success. Resident root biomass increased and soil nitrate concentrations decreased with the presence of C 4 grasses and also across the diversity gradient, suggesting that diverse plots are more competitive because of the presence of C 4 grasses. In addition to this evidence for a sampling effect, we also found evidence for a complementarity effect. Specifically, the percentage of plots that had lower invader biomass than did the best resident monoculture (i.e. that had invader ‘underyielding’) increased across the species richness gradient. This pattern cannot be explained by a sampling effect and is a unique signature of complementarity effects. Our results demonstrate the importance of multiple mechanisms by which diversity can increase invasion resistance.