Lowland tropical rain forests are the world’s most species-rich terrestrial communities. The Center for Tropical Forest Science (http://www.ctfs.si.edu/) has established Forest Dynamics Plots throughout the tropics. In each plot, typically 25–50 ha in area, all trees are tagged and identified to species, and each tree in the plot is measured every 5 years. In the first census of the plot at Yasuni, Ecuador, ecologists recorded 644 tree species in just 1 ha and predicted that the entire plot will contain 1300 tree species! During the first census, 20 species new to science were discovered.

Even though tropical forests occupy only 7% of the Earth’s surface, they harbour about two thirds of the estimated 400 000 plant species in the world. Approximately 855 000 species of insect have been named but some 80–95% have yet to be collected and described and most of these will be found in the tropics (Stork 2007). Bird communities in tropical forests are also tremendously diverse. Blake (2007) recorded 319 bird species within two 100 ha plots at Tiputini in lowland Ecuador. Over 890 bird species have been recorded in Costa Rica, more than in all of the USA and Canada combined.