Vines Are Strangling Trees and Reducing Carbon Storage, Researchers Say

Tarzan certainly made the most of long tree vines but the benefits of jungle "ropes" may end there. Researchers recently discovered that twisting vines, or lianas – increasingly abundant in tropical forests as a result of climate change and severe seasonal drought – are strangling trees, slowing their growth and causing premature death. They also retard carbon storage which negatviely impacts climate change, according to 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," Stefan Schnitzer, co-author of the study and a biology professor at Marquette University, said in a news release. 

Vines are dependent upon strong trees as they climb in search of sunlight that exists only above the multi-layer tree canopy. In lowland tropical forests vines alone make up nearly 25 percent of the species and woody stems present. 

To better understand how vines limit the growth of trees, researchers cut down all lianas within eight experimental plots located in Panama's Barro Colorado Nature Monument, while leaving some vines untouched in others. This stratgy allowed them to monitor and compare growth rates over the next three years. 

So what did they find? Researchers discovered that vines reduced the number of dead leaves and other debris falling from the forest canopy by 76 percent per year in plots where they were present compared to where they had been removed. This reduced biomass accumulation was also linked to lower tree growth and increased mortality where vines grew around trees.

However, that's not all. Vines also reduced the amount of wood that accumulated in the forest floor biomass. This significantly altered the amount of carbon stored, since wood stores carbon for a long time. Leaves quickly rot and release carbon back to the atmosphere.

Understanding this environmental change helps conservationists prepare for the future. And when scientists ran simulations at current rates vine growth over the next 50 years, they found that the slithery plants could ultimately reduce carbon storage by 35 percent. The figures get worse if lianas continue to diversify and spread. 

"This is the first time the effect of lianas on carbon cycling has been shown in such detail and on a large scale," Jennifer Powers, a researcher from the Department of Plant Biology at the University of Minnesota, said in a news release. "It suggests that over the decades to come, lianas could increasingly suppress the ability of tropical forests to sequester carbon."

The study was recently published in the journal Proceedings of the National Academy of Sciences.

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