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 in the forest canopy, providing
arboreal animals—including ants and many other invertebrates, lizards, rodents, sloths, monkeys, and lemurs—with paths through the forest. For example, in the Eastern
tropical forests of
Madagascar many
lemurs achieve higher mobility from the web of lianas draped among the vertical tree species. Many lemurs prefer trees with lianas because of their roots. Lianas are
parasitic; they do not derive nutrients directly from host trees, but live on and indirectly derive nutrients at their expense. Specifically, their growth may greatly reduce their hosts' growth and tree reproduction, greatly increase tree mortality, prevent tree seedlings from establishing, and ultimately decrease tree population growth rates. For example, forests without lianas grow 150% more fruit, and trees with lianas have twice the probability of dying. Lianas are uniquely adapted to living in forests as they use host trees, for stability, to reach to top of the canopy. Lianas directly damage their hosts by mechanical abrasion and strangulation, render hosts more susceptible to ice and wind damage, and increase the probability that the host tree falls. Lianas also provide support for weaker trees when strong winds blow by laterally anchoring them to stronger trees. However, this anchoring can also be destructive because when one tree falls, the connections made by the lianas can cause many other trees to fall. Some lianas attain great length, such as
Bauhinia sp. in
Surinam which has grown as long as . Hawkins has accepted a length of 1.5 km (1 mile) for an
Entada phaseoloides. The longest monocot liana is
Calamus manan (or
Calamus ornatus) at . One way of distinguishing lianas from trees and shrubs is their
stiffness, specifically, the
Young's modulus of various parts of the stem. Trees and shrubs have young twigs and smaller branches that are quite flexible and older growth such as
trunks and large branches that are stiffer. A liana often has stiff young growths and older, more flexible growth at the base of the stem. Because of these stresses, some lianas grow flat ribbon-like stems which are very flexible, including certain
Bauhinia species,
Entada species, some
Tetrastigma species, as well as
Serjania icthyoctonia and
Thinonia scandens, both in the
Sapindaceae. These last two go still further and the ribbon divides into parallel strands. ==Examples==