New research suggests vines could hinder tropical forests' ability to store atmospheric carbon dioxide.
These woody vines, dubbed lianas, slow tropical tree growth and can lead to premature tree death, the Smithsonian Tropical Research Institute reported. The vines can reduce carbon uptake by more than three-quarters, which makes a huge impact on the trees' ability to mediate climate change. Climate change is also believed to be causing an increase in liana growth.
"This study has far-reaching ramifications," said co-author Stefan Schnitzer, a biology professor at Marquette University and a long-term research associate at the Smithsonian Tropical Research Institute. "Lianas contribute only a small fraction of the biomass in tropical forests, but their effects on trees dramatically alter how carbon is accumulated and stored."
Past research has shown lianas have a significant impact on forest biomass growth and accumulation, but those studies focused primarily on tree growth and were restricted to observations of forest gaps. In this new study, the researchers cut lianas in eight experimental plots in a 60-year-old secondary forest, and left them intact in eight others. The status of the plots was monitored for a three-year period.
The scientists observed lianas reduced net biomass accumulation by 76 percent per year. This decrease was caused by lower tree growth and to an increase in tree mortality imposed by the vines. The lianas proved to lower biomass accumulation, and shifted it from carbon-storing wood to leaves. Simulations predicted the change of biomass stocks over the next 50 years in forests affected by the vines will reduce long-term storage of carbon by 35 percent. These reductions could be even more severe if "liana-tree competition" intensifies in the future. The researchers noted that while lianas are problematic, they do have some redeeming qualities.
"In terms of carbon, lianas may be detrimental; however, lianas provide a wide range of resources for wildlife, such as fruits, seeds and fresh leaves, and by connecting trees together lianas provide aerial pathways that are used by the vast majority of arboreal animals to move through the forest," Schnitzer concluded.
The findings were published in a recent edition of the journal Proceedings of the National Academy of Sciences.