Associational resistance mediates interacting effects of herbivores and competitors on fireweed performance

摘要: Abstract Neighboring plants may have dual roles in relation to focal plants, being both competitors, and mediators of associational resistance (AR), or susceptibility (AS) herbivores. Even though these two are played out simultaneously nature, they traditionally been studied separately. We conducted a two-by-two factorial experiment by manipulating the occurrence neighbors (meadowsweet, Filipendula ulmaria) shared mammal herbivores (moose, Alces alces) investigate how affect performance fireweed (Chamerion angustifolium) plants. found that interactions between herbivory had significant effects on performance. These were explained counteracting mechanisms. First, when present, experienced AR such growing outside meadowsweet patches an almost tripled risk browsed compared among meadowsweet, resulting reduced reproduction growth. Second, mammals excluded, association with direct negative effect growth rates – mainly due competition for light. Additionally, first time, we show affected mammal-induced branching fireweed. This study demonstrates mediated can flip plant–plant from competitive (−) facilitative (+), plant architecture. As probably co-occurring forces, likely common thus fundamental importance populations communities.