Liana habitat and host preferences in northern temperate forests

Background/Question/Methods

Lianas and other climbers are important ecological and structural components of forest communities.  Their abundance and density in a given habitat is often dependent on a variety of factors, similar to other plants, such as light, soil moisture and nutrients.  However, since these plants require external support, host characteristics are important to their distribution as well.  Lianas are depauperate in the temperate zones compared with the tropics, leaving them understudied in these regions.  We sought to gain a better understanding of how both liana and herbaceous vines were distributed on the landscape.  We surveyed the climbing plant species in mature (100 years and greater) forested habitats in the Midwestern USA at a variety of scales from simple presence/absence, to groundlayer densities, to those species that had ascended trees.  We also surveyed the tree species that these arboreal climbers were attached to.  Using a variety of statistical methods, including NMS ordination, ANOVA and linear mixed effects models (LME) we examined the relationships between the liana and tree communities.

Results/Conclusions

Canopy cover and soil pH influenced climber species presence/absence and groundlayer climber densities.  The highest number of climber species was in the red oak/dune forest and red maple/red oak tree communities, while the liana:tree ratio was greatest in the black oak/jack pine habitat.  The proportion of arboreal liana species of a given climbing type was significantly related to the diameter at breast height (DBH) of the host tree, with more root climbers being on larger trees, and fewer stem and tendril climbers on large trees.  In general, DBH of climbing lianas was positively related to DBH of the host tree; however, this varied by the identity of the liana and the tree species.  The larger the host tree, the higher the probability that it was colonized by one or more lianas, with certain tree species being more susceptible to lianas than others.  There were very few invasive climbers encountered in these relatively intact habitats, indicating that these mature forests may be buffered from invasion to some extent.  The information obtained about groundlayer and arboreal climbers will provide a baseline for comparison in light of potential changes in the future of both climber identity and abundance in these north temperate forests.