Wisteria floribunda is a deciduous liana species which expands its distribution horizontally through extensive clonal reproduction by stolons. Although clonal reproduction is common but important life history strategy in terms of liana species’ regeneration and colonization success, no studies have evaluated the true contribution of clonal reproduction on stand level liana distribution under natural habitat. In addition, it is considered that clonal reproduction enables lianas to respond rapidly to canopy gap disturbance. We aimed to clarify 1) contribution of clonal reproduction to distribution and regeneration of Wisteria floribunda and 2) the effect of canopy gap disturbance on clonal structure of this species. Present study was conducted in the 6-ha plot of Ogawa Forest Reserve which is the old-growth cool temperate forest of central Japan. Genetic analysis was conducted using 10 microsatellite markers designed for this species to evaluate the clonal structure across the study plot. All individuals higher than 1.3 m aboveground were sampled in 2015 following the liana census conducted in 2013. Canopy height data from 1991 to 2014 for 5 m grid in the study plot was used for analyzing the effect of canopy gap disturbance on clonal structure of W. floribunda.
Results/Conclusions
Out of all samples (N=391), clonal reproduction contributed 71% in abundance and 62% in basal area. Largest genet had the patch size of 0.47 ha and ranged over up to 180 m. Two largest genets ranged over the stream or valley landform, indicating that W. floribunda expanded its distribution not only by stolons but also by laddering host tree crown to another. In contrast to our expectations, no significant difference was found on the distribution of both clonal and non-clonal ramets when canopy gap disturbance was taken into account. We found that clonal reproduction had high contribution on distribution of liana species, and the need of genetic approaches to accurately evaluate the true contribution of clonal reproduction. We also found that little impact of canopy gap disturbance to the distribution of both clonal and non-clonal ramets, indicating the different underlying mechanism for the distribution of liana species in terms of clonal reproduction and disturbances.