Liana vines are long-stemmed, woody vines that are rooted in the soil at ground level and use trees or other means of vertical support to climb up to the canopy to gain access to sunlight. There are numerous varieties from many plant families. And, for reasons that are not entirely clear, their abundance has doubled in recent decades.
The result is that these rapidly expanding woody vines are increasingly shading and choking rainforest trees, reducing the amount of carbon they sequester from the atmosphere.
Trees and plants absorb about a quarter of all the CO2 that we release from tailpipes and smokestacks. Given the expanding role of vines, it is important to know how much carbon liana vines store compared to trees.
Calculating the carbon content of trees or liana vines involves estimating the volume of plant matter, something foresters have long done in calculating the number of wooden planks they can obtain from a tree. But quantifying the volume of carbon stored in liana vines is more challenging because, unlike trees, which generally grow straight up into the canopy, lianas follow erratic and looping paths while reaching the same heights.
Scientists from the U.S., Panama, and the U.K. published a paper in the Proceedings of the National Academy of Sciences that demonstrated that vines can reduce a tropical forest’s ability to absorb CO2. They removed all the vines from several tracts in a liana-choked forest. After three years, a new carbon census showed that the pruned tracts had absorbed 75% more carbon per year than the control areas where vines grew freely.
Why vines are proliferating and whether they will continue to do so is unclear, but it does not seem to be a good thing.
Photo, posted July 12, 2012, courtesy of Kari via Flickr.