A new study by Liming Zhou and colleagues of Albany University reveals how, between 2000 and 2012, the African Congo’s forest cover has turned brown as it adjusts to long term drier conditions. The decline in tree cover revealed by the study is expected to lead to serious habitat loss, as well as dramatic changes in the forest’s ability to store carbon.
The Congo suffers ‘persistent’ drought
The Congo’s forest is the planet’s second biggest rainforest. Since the year 2000 it has suffered from persistent drought. And the climate changes are leading to a dramatic change in the forest’s composition.
More than ten thousand plant species grow there, around 30% of which are unique to the region. It’s also rich in animal life, including chimpanzees, bonobos, gorillas and elephants. There are about a thousand bird species and more than 700 types of fish, making the Congo Basin a particularly unique and precious environment.
The scientists brought the Enhanced Vegetation Index into play to figure out whether the forest’s ‘greenness’ is changing reveal its overall health. The results were worrying. It appears that there’s a steady decline in the region ‘s health and the rainforest’s canopy is steadily becoming less green, more brown. It’s a different picture from the Amazon’s rainforests, where dry episodes kill trees off very quickly.
Tropical droughts take their toll
The Congo Basin is already known to be fairly resilient to moderate climate change, since the dry conditions there have already lasted a few hundred years. But recent climate anomalies caused by human activity and the Atlantic Ocean’s steady warming have created severe tropical droughts which are having a big impact on rainforests.
The browning identified by the team is consistent with regional decreases seen in water levels. The temperature of the Congo as a whole is also on the up, with more sunlight and less cloud cover, a major tree stressor.
More findings on the way as the study continues
The study is set to continue, looking next at the effects of climate change on individual tree species. It may turn out that the unprecedented dry spell might affect evergreens more than deciduous species. It’s vital to find out, since so many global warming models predict tropical forests may suffer worse than other environments from a shortage of water.