Cutting lianas, a diverse group of woody climbing plants, is a well-known way to increase carbon sequestration and timber production. A new paper in the journal Forest Ecology & Management finds that selectively liberating trees from lianas provides substantial carbon benefits at a very low cost.
Infestations of trees by woody climbing plants, commonly called lianas, are common and increasing in an estimated 250 million hectares of selectively logged tropical and temperate forests. Lianas are a natural component of forest ecosystems, particularly in tropical regions. But liana infestations have been expanding and intensifying due to logging, forest fragmentation and other human-caused disturbances.
Indigenous people have long managed lianas to enhance tree growth rates and fruit production. Dozens of recently reviewed experiments document a near doubling of rates of aboveground tree biomass increments after liana removal.
This paper demonstrates that liberating a limited number of “future crop trees” – trees that will eventually be harvested – from lianas enhances carbon removal rates at low cost.
The authors estimate that over 30 years, if applied to five liana-infested trees per hectare, this treatment would result in 800 million metric tons of CO2 removed from the atmosphere by liberated trees in the 250 million hectares of selectively logged and treated forest. The direct cost of this removal would be less than $1 per metric ton.
The Big Picture
To scale natural climate solutions at the pace needed to avoid climate catastrophe, conservationists and forest managers need low-cost, no-regrets practices that can be implemented immediately.
“This is a very inexpensive way to increase carbon sequestration,” says lead author Francis Putz, Distinguished Professor of Biology at the University of Florida who is continuing this research at the University of the Sunshine Coast in Australia. “It’s quite a bit less expensive than other natural climate solutions.”
Seminal research in the natural climate solutions field has used a threshold of $10 per metric ton or less for those NCS that are considered “low cost”.
Putz notes that this treatment should also be attractive to timber companies that are seeing reduced timber yields from harvesting all over the world.
“Trees benefit from reduced competition with lianas,” says Putz. “By extension, so do people who rely on timber and eat the fruits and seeds of trees.”
The paper emphasizes that while cutting all lianas would be bad for biodiversity, the impacts of liberating only a few trees per hectare are likely to be minor. The authors recommend that lianas be cut on only 5-10 trees per hectare, specifically to limit impacts on biodiversity.
“Any intervention in forests, including not doing anything, has a number of trade-offs,” says lead author Putz. “By limiting this liana removal to a small portion of the canopy trees, we’re balancing these trade-offs.”
Putz sees potential for selective liana removal to have a much bigger impact on forest management. Currently, many potentially beneficial forest treatments are not applied due to high costs and a long time to see a return on investment. Liana liberation, in contrast, is a low-cost and easy-to-implement natural climate solution that substantially benefits timber production and the climate.
“The principal benefit of this intervention is that, in selectively logged forests, its application would often represent a first step away from timber mining and toward scientifically-informed forest management,” he says. “Managing for renewable natural resources, and not just exploiting forests, has numerous economic and environmental benefits including the mitigation of global climate change.”