Influence of Landscape Characteristics on Wind Dispersal Efficiency of Calotropis procera

Rubber bush (Calotropis procera), a perennial invasive milkweed, infests large swathes of pastoral land in northern Australia and Queensland, diminishing pasture productivity. The seeds rubber are small with fluffy pappi that confer buoyancy during wind dispersal. Long-distance seed dispersal (LDD) by is dependent part on terminal velocity, the height release above ground, surrounding vegetation, parameters such as speed vertical turbulence. Using empirical data, spatial population distribution, historical knowledge three experimental sites, we examine how traits can interact environmental features to promote We expected naturalised populations have following: (1) higher autocorrelation open plains where distances maximised compared hilly habitats or those tall vegetation; (2) southeast northwest directional bias aligned prevailing winds; (3) patchy satellite ahead an infilled continuous main front. Seed kernels were estimated releasing from dehiscent fruit for four periods ten minutes each at locations fixed while monitoring speed. Five alternative models fitted which log-logistic (Kolgomorov–Smirnov test p = 0.9998), 3-parameter Weibull model (K-S 0.9992), 0.9956) provided best fit order. Stem size distribution was similar leading edges all sites (F10, 395 1.54; 0.12). exponential semivariogram level adopted (Tennant Creek (TC), Helen Springs (HS) Muckaty (MU) (R2 63.8%, 70.3%, 93.7%, respectively). Spatial along predicted southeast-to-northwest bearing evident (TC kriging range 236 m; HS 738 m MU 1779.8 m). distance bimodal conditions, short (SDD) up 55 m, furthest propagules 1.8 km downwind environments. Dispersal directions pronounced no areas vegetation. In designing management strategies, it should be noted invasion risk greater frequently disturbed landscapes, landscapes Northern Australia. Infestations xeric grassland shrubby vegetation priority control maintain high levels productivity beef production systems.