An area of luxuriant forest, found where rainfall exceeds 1 000 mm yr⁻¹. Although rain forest does develop in temperate latitudes, most of the world’s rain forest is tropical. Hill and Hill (2001) PPG 25, 3, 326 explain why tropical rain forests are so species-rich, and Puyravaud et al. (2003) J. Biogeog. 30, 7 applaud the use of vegetation thickets as restoration tools in rain forests.