Lianas (woody climbers) are an important component of tropical rainforests. A liana that does not have a self-supporting phase would employ an avoidance strategy, whereas a liana with a self-supporting phase would switch from a tolerance to an avoidance strategy. There have been few tests of the differences in strategies between lianas with different juvenile life history traits. Prof. CAO Kunfang and his students of Xishuangbanna Tropical Botanical Garden (XTBG) investigated the ecophysiological strategies displayed by a liana that tolerates the shaded forest understory and those of a liana that avoids the shaded forest understory during the juvenile stage.

     The researchers compared the morphophysiological characteristics of two Rhamnaceae species: Ventilago calyculata (an immediate obligate climber) and Ziziphus attopensis (having a long self-supporting phase), which both are hook climbers and large, evergreen, late-successional lianas. They quantified growth traits, biomass allocation, mechanics, anatomy, and hydraulics of saplings of the two species. They also evaluated the mechanics, anatomy, and hydraulics for the mature individuals of the two species, to evaluate whether those characters remained constant over the life history of each liana.

They addressed the two questions: (1) do the two strategies differ in growth, biomass allocation, xylem anatomy, mechanical properties, or stem and leaf hydraulic properties? (2) How do those traits reflect two contrasting liana adaptive strategies in the understory?

The two liana species (Ventilago calyculata and Ziziphus attopensis) represented different life history strategies, with Z. attopensis employing a shade tolerance strategy (tolerating the shaded forest understory) and V. calyculata representing a shade avoidance strategy (avoiding the shaded forest understory). Based on the growth habits, the two species exhibited significant differences in their growth, biomass allocation, anatomy, mechanical properties, and leaf physiology, but not in hydraulics. However, to determine whether those are general characteristics related to growth habits, further study of more species is needed.

The study entitled “Different biomechanical design and ecophysiological strategies in juveniles of two liana species with contrasting growth habit” has been published online in American Journal of Botany.