A liana is a long-stemmed, woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the canopy in search of direct sunlight.[1] The word liana does not refer to a taxonomic grouping, but rather a habit of plant growth – much like tree or shrub. It comes from standard French liane, itself from an Antilles French dialect word meaning to sheave.[citation needed]
Lianas are characteristic of tropical moist broadleaf forests (especially seasonal forests), but may be found in temperate rainforests and temperate deciduous forests. There are also temperate lianas, for example the members of the Clematis or Vitis (wild grape) genera. Lianas can form bridges amidst the forest canopy, providing arboreal animals, including ants and many other invertebrates, lizards, rodents, sloths, monkeys, and lemurs with paths across the forest. For example, in the Eastern tropical forests of Madagascar, many lemurs achieve higher mobility from the web of lianas draped amongst the vertical tree species. Many lemurs prefer trees with lianas for their roost sites.[2]
Lianas do not derive nutrients directly from trees but live on and derive nutrients at the expense of trees, thus they are parasites of trees. [3][4] Specifically, they greatly reduce tree growth[5] and tree reproduction,[6] greatly increase tree mortality,[7] prevent tree seedlings from establishing,[5] alter the course of regeneration in forests,[8] and ultimately decrease tree population growth rates.[9] For example, forests without lianas grow 150% more fruit; trees with lianas have twice the probability of dying.[10]
Lianas are uniquely adapted to living in such forests as they use the host tree, for stability, to reach to top of the canopy. Lianas directly damage hosts by mechanical abrasion and strangulation, render hosts more susceptible to ice and wind damage,[citation needed] and increase the probability that the host tree falls.[citation needed] Lianas also provide support for weaker trees when strong winds blow by laterally anchoring them to stronger trees.[11] However, they may be destructive in that when one tree falls, the connections made by the lianas may cause many other trees to fall.[11] Because of these negative effects, trees which remain free of lianas are at an advantage; some species have evolved characteristics which help them avoid or shed lianas.[12]
Some lianas attain to great length, such as Bauhinia sp. in Surinam which has grown as long as 600 meters.[13][14] Hawkins has accepted a length of 1.5 km for an Entada phaseoloides.[15] The longest monocot liana is Calamus manan (or Calamus ornatus) at exactly 240 meters.[16] One way of distinguishing lianas from trees and shrubs is based on the stiffness, specifically, the Young's modulus of various parts of the stem. Trees and shrubs have young twigs and smaller branches which are quite flexible and older growth such as trunks and large branches which are stiffer. A liana often has stiff young growths and older, more flexible growth at the base of the stem.[17]
Some families and genera containing liana species include:
