In a bid last week to show his country's commitment to curbing the multibillion-dollar-a-year illegal ivory trade, Chadian President Idriss Déby set aflame a large pile of confiscated tusks during a ceremony marking the 50th anniversary of Zakouma National Park. The park was home to 4,000 elephants about a decade ago, but that figure has dwindled to just 450 today. The World Wildlife Fund reports more than 20,000 elephants are killed around the world every year for their ivory tusks, with the majority in Central Africa. Recent steps have been taken to reverse the trend; the U.N. Security Council linked wildlife trafficking in the Democratic Republic of Congo to the country's deadly conflicts and the U.S. issued a ban on the commercial trade of elephant ivory. But park rangers on the ground say more must be done to fend off the well-armed poachers, some of whom cross the region's porous borders. AFP photojournalist Marco Longari, who TIME named the Best Photographer on the Wires in 2012, documented the ceremony as well as the park's efforts to track and defend the animals.