According to the Report, the threat to species diversity is human-caused.[16] The main cause is the human land requirement, which deprives other species of their habitats.[8] In the past 50 years, the world's human population has doubled[17] and biodiversity has suffered a catastrophic decline.[18] Most notably, tropical forests have been cleared for cattle pastures in South America and for oil-palm plantations in Southeast Asia.[19] Some 32 million hectares (79 million acres) of tropical rainforest were destroyed between 2010 and 2015, compared to the 100 million hectares (250 million acres) lost in the latter two decades of the 20th century.