Degraded forests are almost as dangerous as deforestation itself, with surprisingly dramatic reductions in their ability to hang onto carbon. The world’s tropical rainforests hold onto a massive 30% of the planet’s terrestrial carbon. So we mess with them at our peril. A particularly scary side effect of the human activity in rainforests and the subsequent forest degradation is a sinister increase in the number of vines found on damaged plots.
Vines play a big part in rainforest carbon capture
As a general rule, more vines means less carbon is captured by forests, as discovered by a study carried out by the Smithsonian Tropical Research Institute. It’s counter-intuitive but true – as rainforest cover re-grows over abandoned agricultural land, the scientists involved fully expected the new growth to effectively mop up vast amounts of atmospheric carbon. But it looks like an increase in vine cover does the opposite, hampering the new growth’s potential and causing rainforests to release even more of their carbon.
The researchers cut woody vines, AKA lianas, out of forest plots, comparing liana-free areas with liana-rich. In total they collected eight years’ worth of data, quantifying the extent to which the vines limit the growth of trees and, as a result, the amount of carbon the rainforest can absorb.
Inter-plant competition can be catastrophic
The study is the first to demonstrate experimentally how competition between different types of plant can lead to catastrophic ecosystem-wide losses of carbon. And lianas are the worst culprits. They can cut forest biomass by a depressing 20%, although it could easily be more – the scientists involved in the research said their estimate was ‘conservative’.
It just goes to prove the incredible, delicate, easily-damaged complexity of the rainforest ecosystem. Leave it alone to maintain its own ancient natural balance and it does the job it is designed to do. Tweak the balance even a little and the entire pattern changes.
Article by the Rainforest Foundation.