The trees are illegally burned and cut down in costal districts of Tanzania to set up sesame farms. As Tanzania is Africa’s largest producer of sesame seed, domestic exporters are pushing formers to increase the production.   According to the Tanzania Forest Services Agency, sesame agriculture is a primary driver of deforestation.

https://news.mongabay.com/2017/03/in-tanzania-a-surge-in-sesame-farming-poses-threat-to-natural-forest/