HOST ASSOCIATIONS OF 2 ADVENTITIOUS-ROOT-CLIMBING VINES IN A NORTH QUEENSLAND TROPICAL RAIN-FOREST

The abundance of adventitious-root-climbing vines, predominantly Freyc inetia excelsa and Piper caninum, on potential host trees was investig ated in a north Queensland tropical rain forest. All trees 10 cm DBH a nd greater were measured and assessed For adventitious-root-climber pr esence. Additional trees of the 17 most abundant species were examined giving a total of 833 trees. Some 1694 adventitious-root climbing vin es were recorded from the study area. Distribution over the rain fores t trees was not homogeneous, bur exhibited host associations. Interspe cific differences between potential host trees were analyzed in terms of allelopathy, bark characteristics, and gross morphological features . Bark characteristics are proposed.as the main factor for the relativ e absence of adventitious-root-climbing vines on trees of Syzgium papy raceum and Austromyrtus shepherdii. Thin, peeling, sloughable bark cha racterize these members of the Myrtaceae. Trees heavily infested by ad ventitious-root climbers include Beilschmiedia collina with non-descri pt (though slightly rough) bark providing a good, stable climbing surf ace with little phytotoxicity, and Citronella smythii, with thick, cor ky, fissured bark, also lacking allelopathic materials. Allelopathic e ffects of bark phytochemicals seem to be predominantly responsible for the absence of infestation of Alphitonia petriei by adventitious-root climbers.