Vines May Strangle Carbon Storage in Tropical Forests by Inhibiting Tree Growth

Vines may actually strangle carbon storage in tropical forests. It turns out that woody wines, or lianas, slow tropical forest tree growth and may actually cause premature tree death, limiting tropical forest carbon uptake.

Tropical forests account for about a third of the total carbon fixed by photosynthesis. However, the increasing number of lianas may cause this fixation to decrease over time. Spurred by either changing climate, increased disturbance or more severe seasonal drought, the increasing vines could be a huge issue for tropical forests.

Lianas are actually characteristic of lowland tropical forests, often making up more than 25 percent of species and woody stems. They depend on trees for support, climbing into sunlit treetops. These vines can actually invest a great percentage of their own biomass in leaves.

In this latest study, though, the researchers wanted to see how lianas impacted tree growth. The scientists cut lianas in eight experimental plots in a 60-year-old secondary forest, and left lianas in eight other experimental plots.

The researchers found that by the third year, lianas reduced net biomass accumulation by 76 percent per year in plots where they were present compared to the areas where they had been removed. The proportion of biomass in leaves versus wood also differed; forest canopy productivity decreased by 14 percent in liana-free plots while productivity of woody stems rose almost 65 percent.

The findings have important implications for the capacity of tropical forests to serve as carbon sinks in the future. Because lianas can reduce long-term storage of carbon by 35 percent, it's crucial to understand how lianas will increase in the future.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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