Clonal Expansion Accounts for Most Post‐Disturbance Proliferation of a Dominant Temperate Liana, Wisteria floribunda , Across a Fragmented Forest La

ABSTRACT

Large‐scale anthropogenic disturbances, including deforestation and fragmentation, are increasing worldwide. Lianas often proliferate after such events, yet the mechanisms underlying these increases—particularly their demographic sources—remain unclear. We quantified the extent to which clonal expansion, rather than seed recruitment, accounts for post‐disturbance proliferation of Wisteria floribunda (Fabaceae), the dominant liana in a 21.6‐ha fragmented forest landscape in Japan. We divided the study area into 20 × 20 m grid cells, randomly sampled up to one W. floribunda ramet per cell, and genotyped 273 ramets at 10 microsatellite loci to assign ramets to genets and quantify genet areas and their spatial distribution. Genotyping revealed a substantial contribution of extensive clonal reproduction: 83% of ramets were clonal, resolving into 47 genets. These genets collectively occupied 58% of the 21.6‐ha study area, and expansion produced extensive genets—the largest covered 9.5 ha. Several genets spanned multiple forest patches; three multi‐patch genets accounted for 43% of all ramets, including one spanning seven patches. Multi‐patch genets were concentrated within areas covered by forests prior to disturbance (odds ratio = 6.83; p  < 0.001). Clonal expansion thus accounts for most post‐disturbance proliferation, while seed recruitment likely contributes to establishment in newly formed forest patches. Some genets attain broad spatial coverage in a fragmented forest, and part of this dominance reflects legacy effects of genets established prior to disturbance. Explicitly accounting for clonal contributions and genet spatial scale is critical for accuratly predicting disturbance‐driven liana dynamics.