Which environment is characterized by the highest diversity of tree species?

Of all the different environments on the planet, the one that sticks out as by far the most diverse in tree species (also all plants, and animals) is the tropical rain forest. The conditions in here are perfect for diversification of the trees, the high competition made them adapt to lots of different species that take different niches, the constant summer with warm climate and almost daily rainfalls, contributes for a perfect conditions for their development.