Lan Qie, of Imperial College London, highlights a second major threat to Borneo's forests: fragmentation. It is a "persistent and progressive threat," said Qie, whose research has shown that forest edges adjacent to fields or oil palm plantations are important sources of energy. carbon emissions because trees are more likely to die.
A fragment must be larger than 300 hectares (about one square mile) for carbon absorption to outweigh the loss of carbon, reported Qie and his colleagues.
But even where there are still intact forests, the extreme episodes of El Niño can unbalance these forests. The Qie study also revealed that the El Niño phenomenon of 1997-98, which was more pronounced in the region than in 2015-2016, caused tree mortality due to drought such as forests intact of Borneo have switched from the carbon sink to the source.
The good news is that these forests have quickly recovered, suggesting that intact forests have some degree of resilience to severe drought, Qie added. The Dipterocarp forests of Southeast Asia have evolved "under a climatic regime that includes El Niño-driven super-annual droughts," she added, with synchronized and periodic seedlings that occur in the south-east. adapt to these conditions. But, as we saw in the Amazon, "it is possible that the resilience of Borneo [carbon] wells could also be contested in the future, "Qie concluded.
Again, it's "how much is too much," but no one currently knows where the tipping point may be, beyond which stressed tropical forests will not be able to recover.
Discover Congo
Until recently, Indonesian peatlands were considered the largest tropical peatlands in the world. But in January 2017, scientists released the confirmation of a discovery: the Congo Basin peat forests covering 145,500 square kilometers (56,177 square miles) dropped Indonesian peatlands to second place.
With peat bogs in Congo containing 30 billion tonnes of carbon, the future of African rainforests is even more critical for the global carbon cycle than scientists realized at the time of the launch. OCO-2 in 2014.
The OCO-2 research revealed that African rainforests did not dry up during the 2015-16 El Niño episode: instead, rainfall levels remained normal. But temperatures have increased, leading to an increase in ecosystem respiration, which has led to an increase in CO emissions.
However, as the weather data in the field is so limited in tropical Africa, OCO-2 scientists have indicated that it is "difficult to verify" the link between temperature and carbon emissions identified by their data and models of remote sensing.
This lack of data is also an obstacle when looking to the future. "[T]There are still many uncertainties as to how the climate will change in Central Africa in response to increasing greenhouse gas emissions, "said Greta Dargie, who led research on Congolese peatlands across the region. "