Illegal timber sales from Senegal to Gambia could see the Casamance forest depleted significantly in the next two years, the former environment minister said Thursday.

Deforestation in the southern Casamance region has accelerated since 2010 because of the illegal sales, said ecologist Haidar El Ali. Aerial footage taken during a research trip shows thousands of rosewood logs being collected in Senegal and deposited in neighboring Gambia, where depots operate about 1 kilometer (half a mile) from the border, he said. Much of the wood is then sold to China, he said.

Timber exports from Senegal are illegal and to fight deforestation those illegally chopping trees in Senegal need to be punished, exportation licenses need to be checked and international sanctions on the export of wood from Gambia need to be considered, said El Ali.

Senegal has a larger portion of forest than Gambia, which it mostly surrounds. The Casamance region has 30,000 hectares (74,000 acres) of forest remaining, while Gambia has just 4,000 hectares (9,800 acres), according to watchdog group Global Forest Watch.

However, Chinese rosewood import volumes from Gambia were second only to Nigeria in all of West Africa, according to Chinese customs data gathered by El Ali. As of 2015, more than half of China's imports of such wood came from Africa, he said.

While Senegal has lost more than 1 million trees since 2010, he said, Gambia has generated close to $240 million in sales to China, where there demand for the wood for furniture.

About 25 percent of the Casamance forest has disappeared from 2010 to 2015, and El Ali estimates the rate could increase.

"If this trend continues, it's clear that in two years the desert will have taken over Casamance irredeemably," said El Ali. "Soon the only thing growing will be climate refugees."