Wetenschap - 20 juni 2002

Ecological importance of lianas is underestimated

Ecological importance of lianas is underestimated

Tropical forest ecologist Professor Frans Bongers has had numerous encounters with lianas during his career and believes that their diversity and value for both ecosystems and humans is seriously underestimated. "They provide important pathways for animals and are a rich source of medicines."

Over the years many secrets of tropical forests have been revealed thanks to hard scientific work. Biologists now know much about bats, giant anteaters and kinkajous. All interesting phenomena according to Bongers who has conducted himself and supervised many studies in the forests of Guyana, Cameroon and the Ivory Coast. But it is now time to pay serious attention to the climbing champions of the world's forests, the lianas. He recently published an article on them in the journal Trends in Ecology and Evolution.

"Some researchers assume that lianas only play a limited role in forest dynamics and therefore they have been neglected in most community-level forest studies. But lianas are important players in many areas of forest ecology," says Bongers. Ascending from the forest floor to the canopy with the help of thorns, adhesive hairs and roots, lianas provide essential food and much needed canopy structure to forest animals. The variety of lianas is enormous. In the forests on the rim of the Amazon basin there is an average of 51 species per hectare, and as such lianas contribute a great deal to plant diversity in the tropics.

Bongers continues: "Just as important is the value of lianas to the human populations in the forests. Medicines are distilled from liana plant material and the juices they contain. In the Ivory Coast I recorded 114 liana species used by the people there, especially for medicinal purposes, but also for construction materials."

Lianas face threats, and a major one is logging. Loggers in tropical areas often cut lianas before felling trees to prevent the lianas from pulling other trees down at the same time. Bongers is not convinced that this is always necessary as t hey are not always strong enough to pull down nearby trees. An experiment Bongers conducted recently with PhD student Marc Parren in southern Cameroon proved him right. "Liana cutting is not very expensive, but in terms of ecological damage the price is high. Cut down the lianas and you lose food for animals, plant diversity and products for local people."

Hugo Bouter