The young plant, protected by a makeshift fence of wood and wire, is a kind of dragon’s blood tree — a species found only on the Yemeni island of Socotra that is now struggling to survive intensifying threats from climate change. “Seeing the trees die, it’s like losing one of your babies,” said Keybani, whose family runs a nursery dedicated to preserving the species. Known for their mushroom-shaped canopies and the blood-red sap that courses through their wood, the trees once stood in great numbers.