Tourists marvel at two iconic trees (Shorea leprosula Miq. and Ficus albipila (Miq.) King), known as the 'couple tree', in Kebun Raya, Bogor, Indonesia. Trees sustain life on this planet and enrich our lives in multiple ways. However, we are losing tree diversity at an alarming rate. Cannon et al’s article “The Global Tree Assessment provides a multifaceted view on the future of tree diversity conservation” highlights the work of the Global Tree Assessment through the lens of 13 articles that make up this special issue. A concerted global effort is needed across scales and disciplines to ensure a comprehensive picture of tree diversity and allow trees to be protected for the benefit of plants, people and the planet.