How to differentiate facilitation and environmentally driven co‐existence

Abstract Positive plant–plant interactions (i.e. facilitation) receive increasing attention as a potentially important driver of community assembly. We conducted a systematic literature review indicating broad support for positive effects of potential facilitator species. However, a large majority of the reviewed studies (83% for field studies, 57% for experiments) share a similar risk of misinterpretation as they assess facilitative effects by comparing plots inhabited by a potential facilitator with randomly placed control plots nearby (paired sampling). As the distribution of facilitator species may itself be environmentally driven, species co‐existence caused by facilitation cannot exclusively be separated from environmental effects (habitat sharing). Based on simulated plant communities and sampling protocols, we show how non‐random co‐existence can occur in the absence of facilitation.…