Can limiting similarity increase invasion resistance? A meta-analysis of experimental studies

We used meta-analyses to examine experimental evidence that functional similarity between invaders and resident communities reduces invasion. We synthesized evidence from studies that experimentally added seed to resident communities in which the functional group composition had been manipulated. We found communities containing functionally similar resident species reduced invasion of forb but not grass invaders. However, experimental design dramatically influenced the results – with evidence for limiting similarity only
found in artificially assembled communities, and not when studies used functional group removal from more ‘natural communities’. We suggest that functional group similarity plays a limited role in biotic resistance in
established communities.