A massive collaborative study of the world’s tropical forests, undertaken in an attempt to clarify what the effect of increased carbon dioxide in the atmosphere and higher temperatures could be on tropical forests, has shown that biodiversity loss may not be as bad as previously thought. A group of 30 forest scientists joined forces to look at 20 year’s worth of tree-width measurements – more than 2-million in all – from 12 tropical forests, ScienceNow Daily News reports.

Previously, studies had suggested that higher carbon dioxide levels and warmer temperatures would benefit fast-growing trees, which would eventually crowd out the slower growing species, resulting in overall biodiversity loss. The results of the latest study show that this does not appear to be the case: fast- and slow-growing trees increased roughly equally in biomass during the years of study, the report said.

Another theory is that climate change could have a “fertilisation effect” that helps all forest species to grow faster. The study did not show clearly whether this is in fact the case, though. Overall forest biomass was found to have increased, but it may not be anything to do with carbon dioxide and warming temperatures, a co-author of the study said. The forest may have been recovering from other stressors such as logging or El Nino events. Another study is planned for later this year in the Amazon to look further at the fertilisation issue.