Final answer:
The Tropical Rainforest is characterized by the highest diversity of tree species due to the consistently warm temperatures and high levels of precipitation.
Step-by-step explanation:
The environment characterized by the highest diversity of tree species is the Tropical Rainforest. Tropical rainforests are the most diverse terrestrial biome and are found in equatorial regions. These forests have a wide variety of plant and animal life due to the consistently warm temperatures and high levels of precipitation, which provide ideal conditions for tree growth.