Complex sentence: In 1996 these protected areas were united to found the Alexander von Humboldt National Park, the most important biosphere reserve in the Caribbean basin, which, along with Cuchillas de Toa was declared a UNESCO World Natural Heritage Site in 2001.
Split into simpler sentences: In 1996 these protected areas were united to form a National Park that was named after Alexander von Humboldt. Being one of the most important biosphere reserves in the Caribbean basin, the National Park, along with Cuchillas del Toa was declared a UNESCO World Natural Heritage Site in 2001.