Fine root anatomical and morphological traits of three temperate liana species in northeastern China

Objective  The objective was to investigate the functional traits and potential absorbing capacity in fine roots of liana (woody climbing plants) in temperate forests.

Method  We sampled three typical temperate liana species in northeastern China, including two twining climbers (Actinidia kolomikta and Schisandra chinensis) and one tendril climber (Vitis amurensis). The anatomical, morphological, and branching traits, as well as the composition of absorptive roots were examined for the grade 1−5 fine roots in the three species.

Result  The results showed that the cortical thickness of Actinidia kolomikta and Schisandra chinensis increased by ascending branch order, while that of Vitis amurensis decreased. The stele diameter of all three liana species significantly increased with increasing branch order, but the ratio of cortical thickness to stele diameter significantly reduced. In term of the status of cortex appearance, the proportion of roots with absorbing function apparently decreased with ascending branch order across all three species, with the grade 1 fine roots as typical absorptive roots. From grade 1 to 5, specific root length significantly decreased, but root diameter and tissue density increased. The decline in root branching ratio associated with increasing branch order was only found in V. amurensis. Those root functional traits in liana were significantly influenced by tree species, but showing significant interaction with branch orders. Compared with two twining climbers, tendril climber of V. amurensis had wider stele, lower ratio of cortical thickness to stele diameter, and much higher branching ratio to the grade 2 and grade 3 roots. In comparison to other woody plants and herbaceous ferns at the same study site, mean root diameter of three liana species was thicker but mean specific root length was lower, with intermediate mean tissue root density.

Conclusion  Although the interspecific differences in root anatomical and morphological traits exist in three temperate liana species, the variation patterns of those root traits associated with increasing branch order are consistent with other woody plants. The morphological traits of the grade 1 roots in these lianas display distinctive characteristics compared with other plant taxa in this region.