According to a new survey of the Amazon, the planet’s largest forest is shifting its composition in response to climate change.
Unfortunately, the research suggests the Amazon isn’t evolving fast enough. The climate is changing faster than the Amazon can adapt.
Most noticeably, scientists found moisture-loving tree species are dying off faster than they can be replaced by species that can withstand drier conditions. Droughts during the last decades have damaged large portions of the Amazon.
“The ecosystem’s response is lagging behind the rate of climate change,” Adriane Esquivel Muelbert, geographer at the University of Leeds, said in a news release. “The data showed us that the droughts that hit the Amazon basin in the last decades had serious consequences for the makeup of the forest, with higher mortality in tree species most vulnerable to droughts and not enough compensatory growth in species better equipped to survive drier conditions.”
The survey, published this week in the journal Global Change Biology, also showed increasing levels of carbon dioxide are benefiting canopy species in the forest’s upper layers.
Additionally, some smaller tree species are benefiting from the increase in CO2 and the deaths of larger, moisture-loving trees.
Previous studies have predicted rising CO2 levels will accelerate at least some forest dynamics, allowing advantaged species to boost their photosynthesis rates and conquer new territory.
“The increase in some pioneer trees, such as the extremely fast growing Cecropia, is consistent with the observed changes in forest dynamics, which may also ultimately be driven by increased carbon dioxide levels,” said Oliver Phillips, professor of tropical ecology at Leeds.
While change can help the Amazon adapt to changing conditions, rapid shifts can destabilize ecosystems.
“The impact of climate change on forest communities has important consequences for rain forest biodiversity,” said Kyle Dexter, from the University of Edinburgh. “The species most vulnerable to droughts are doubly at risk, as they are typically the ones restricted to fewer locations in the heart of the Amazon, which make them more likely to be extinct if this process continues.”