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Figs and Vines

Male, T. D. and G. E. Roberts. Host preferences of the strangler fig Ficus watkinsiana: possible causative factors.

Abstract: The distribution of epiphytic organisms is limited by the availability of and dispersal to suitable hosts.  We examined the distribution of a hemiepiphytic strangler fig, Ficus watkinsiana in Cooloola National Park (Queensland, Australia), in order to determine whether this species exhibits a preference for certain host species. We also assessed characteristics of potential hosts, such as bark roughness and flakiness, fruit type, tree size, and tree age, that might explain the observed distribution of F. watkinsiana.  We surveyed over 1900 potential host trees of the 30 most common forest canopy species, and found that host size, age, and species were all significant predictors of  F. watkinsiana parasitism rate.   The parasitism rate was significantly higher for larger trees (Kruskal-Wallis test, H = 142.30  DF = 1  P < 0.0005 ), and for older trees (chi-square = 21.336, df = 4, p < 0.005). After controlling for host size and age, F. watkinsiana prevalence still differed significantly between host species  (chi-square = 54.612, df = 24, p< 0.005) and these differences were not successfully explained by variation in bark and fruit characteristics.  Given the high prevalence of figs on some host species and the lethal result of fig establishment on hosts, we believe that Ficus parasitism may result in a downward shift in the size distributions of some canopy species, thus limiting the dominance of these host species in the forest.

 

Ficus watkinsiana individual strangling a Lophostemon confertus tree in Cooloola National Park, Queensland, Australia

 

Carsten, L. D., F. A. Juola, T. D. Male, and S. Cherry.  Host Associations of lianas in a southeast Queensland rainforest.

Abstract: Lianas are abundant in tropical forests around the world yet little is known about their ecology.  In this study we report the results of a survey of  the  presence or absence of ten common liana species on 27 tree species in Cooloola National Park, Queensland, Australia.  We found significant positive and negative associations between some liana and tree species.  Our results indicate that host tree diameter is the best predictor of the likelihood of any particular association.  Host tree fruit type was an important factor for several vine types.  Roughness and flakiness of bark interacted with each other to select for high numbers of vines at intermediate levels of both variables.  Although we established associative patterns between vine species and these variables, the model suggested that other unidentified variables may also be important in determining presence/absence of vine species.