AMAZONIAN hydropower developments may do more harm than previously thought, according to Scottish-led research.
Dr Isabel Jones of Stirling University found the long woody vines popularised in Tarzan thrive when trees are fragmented by flooding associated with water-based electricity projects.
However, the plants, known as lianas, can kill trees or prevent them from growing, reducing food and shelter for animals and reducing the forest’s ability to uptake and store carbon.
The findings follow work around the Balbina hydroelectric dam in Brazil, which also involved experts from the University of East Anglia, the Smithsonian Tropical Research Institute in Panama and Brazil’s Universidade Estadual de Santa Cruz.
The results are said to have major implications for planning and efforts to tackle climate change.
Jones, who led the study, said: “If lianas are being favoured in this dam-induced landscape, then the biodiversity and carbon losses associated with tropical hydropower could be greater than expected.
“This is due to the potential increased loss of tree biomass, due to liana-tree competition, as lianas have lower biomass relative to trees.
“Therefore, a shift towards liana-dominated forest on tropical reservoir islands may result in even more biodiversity and carbon losses for already controversial tropical dams.
“These issues identified in this study should be accounted for in the carbon cost and benefit decision-making process of whether to construct new dams in Amazonia.”
The team surveyed almost 90 forest plots across nearly 40 islands and in continuous forests surrounding the reservoir associated with the power project.
It found that while trees rapidly degrade in a dam-induced habitat, lianas remain intact.
Jones said: “At present, islands are not included in environmental impact assessments, which causes a significant underestimation of the negative impacts of tropical dams.
“Given that Brazil alone has plans for several new mega-dams, which will flood vast areas of highly diverse tropical forests, it is important that the total area of islands should be included in calculations considering the habitat impacted by dam creation.
“Our research highlights yet another way that tropical dams can result in long-term carbon emissions and damage to globally important ecosystems.”
The study is published in the PLOS ONE scientific journal.
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